bluuebunny/crossref_metadata_2025 huggingface dataset:
Congenital fiber type disproportion in identical twins
Authors: Curless Richard G. , Nelson Marilyn B.
Published: December 2004

Eighteen‐month‐old identical twins with the muscle histological characteristics of congenital fiber type disproportion are reported. The fiber typing system of pH‐dependent adenosine triphosphatase was used to analyze the size and percentage of type 1, 2A, and 2B fibers in muscle tissue obtained by needle biopsy. Both twins had significantly larger type 2 than type 1 fibers, with 2B fibers representing the largest type. One patient also had type 1 predominance at the expense of a reduction in 2B (2B deficiency). The probands as well as other family members had transient delayed motor development, macrocephaly, and normal intelligence. A biopsy obtained from 1 of these family members failed to demonstrate a similar histological abnormality. The disorder is nonprogressive in this family, as evidenced by minimal disability in the older members and gradual improvement in the probands.
Emotional sequelae of head injury
Authors: Dikmen Sureyya , Reitan Ralph M.
Published: December 2004

The emotional after‐effects of head injury in relation to acuteness versus chronicity of the injury and neuropsychological deficits were studied. The results indicate that there is a decline in emotional distress over time after the injury and show that patients with significant initial and residual neuropsychological deficits experience greater emotional distress than those with negligible difficulties.
Rabies: Recent advances in pathogenesis and control
Authors: Miller Aaron , Nathanson Neal
Published: December 2004

Current knowledge of rabies is reviewed, with emphasis on recent developments in virology, immunology, pathogenesis, treatment, and prophylaxis. Although only a few cases of human rabies occur annually in the United States, the infection is enzootic in wildlife, and an estimated 30,000 possible exposures requiring treatment occur each year.

Rabies belongs to the family rhabdovirus, and its molecular anatomy and biochemistry of replication have been described in some detail. There have been advances in measurement of antirabies antibodies, and techniques for measuring cellular immune response have recently been developed. Early stages of infection are more fully understood, with a hypothesis to explain peripheral sequestration of virus during prolonged incubation periods. Rabies was once thought to be uniformly fatal, but a few patients have survived with aggressive supportive measures. A newly developed vaccine (soon to be licensed in the United States) has been shown highly potent for preexposure immunization and promises to be very effective for postexposure prophylaxis. Current Public Health Service recommendations for postexposure treatment are summarized. Recent research has suggested a novel approach to control of wildlife rabies through oral immunization.
Calcification of axons in experimental spinal cord trauma
Authors: Balentine J. Douglas , Spector Myron
Published: December 2004

Selective discrete intraaxoplasmic deposits of hydroxyapatite crystallites were observed in adult male rats subjected to experimental trauma to the lumbosacral spinal cord. Although previously unreported in spinal cord trauma, the presence of these deposits in minimally altered axons and during the early posttrauma period suggests that such selective calcification may be of more than secondary significance. In view of the current emphasis on cytotoxicity of calcium, especially in relation to axonal degeneration, an evaluation of the role of calcium in augmenting traumatic spinal cord necrosis is warranted.
Chronic neurogenic quadriceps amyotrophy
Authors: Furukawa Tetsuo , Akagami Noriko , Maruyama Shoichi
Published: December 2004

Two patients with chronic neurogenic quadriceps amyotrophy are reported. A 61‐year‐old woman had symmetrical wasting and weakness of the quadriceps femoris of eight years' duration. A biopsy revealed neuropathic changes, and electromyograms showed neurogenic as well as myopathic patterns in the quadriceps and other muscles. A 29‐year‐old woman had long‐standing wasting limited to the quadriceps and hip muscles. EMG and biopsy were compatible with neurogenic atrophy. She had a brother suffereing from a more widespread and severe form of the disease. These cases suggest that chronic neurogenic quadriceps amyotrophy is a forme fruste of Kugelberg‐Welander disease.
Visual evoked potentials and postmortem findings in a case of cortical blindness
Authors: Spehlmann Rainer , Gross Robert A. , Ho Sam U. , Leestma Jan E. , Norcross Karyl A.
Published: December 2004

A patient with cortical blindness due to extensive bilateral posterior cerebral infarcts showed occipital visual evoked potentials to flash stimulation on repeated testing. These responses were probably mediated by extrageniculocalcarine connections between the optic nerve and the secondary visual cortex of the occipital convexity.
Neuropathological changes in cerebellar biopsies of epileptic patients
Authors: Salcman Michael , Defendini Richard , Correll James , Gilman Sid
Published: December 2004

In 5 patients with pharmacologically intractable epilepsy, biopsy of the cerebellar cortex at the time of surface electrode implantation for therapeutic stimulation demonstrated marked degeneration of the Purkinje cell layer in every case. Two of the patients had never experienced a generalized convulsion. Comparison of these biopsy findings with the autopsy findings in two other groups of patients with a seizure disorder of different duration and severity and with the findings in other reported series suggests that permanent neuronal damage in epilepsy is related to the cumulative effects of the frequency and chronicity of the disorder. The pathogenesis remains unclear. The histopathological changes are identical to those seen in generalized cerebral hypoxia, but the observations in our series support the view that in epilepsy the pathogenesis may not be hypoxic.
Epidural spinal cord compression from metastatic tumor: Diagnosis and treatment
Authors: Gilbert Robert W. , Kim Jae‐Ho , Posner Jerome B.
Published: December 2004

The clinical findings in 130 consecutive cases of spinal cord compression by metastatic extradural tumors were analyzed. These 130 patients were combined with a previous survey of 105 patients to compare the effectiveness of radiation therapy (RT) alone with that of surgical decompression followed by RT. Ambulation after treatment was considered a successful outcome. The most common primary tumors producing spinal cord compression were (in order) breast, lung, prostate, and kidney. In 68% of these tumors the thoracic region was involved. Pain was the primary symptom in 96% of the patients, while motor or sensory deficits (or both) were found in 82% of them. Therapy consisted of surgery and RT in 65 patients and RT alone in 170 patients. There were no differences in outcome between those treated by surgery combined with RT and those managed by RT alone. Patients with radiosensitive tumors and those ambulatory at the onset of treatment benefited whether treated by surgery or by RT. Seventy‐five percent of living patients who improved from treatment remained ambulatory at 6 months, and approximately 50% of living patients were ambulatory at 1 year. We conclude that RT without decompressive laminectomy is as effective as decompressive laminectomy in treating epidural spinal cord compression from systemic cancer.
Creatine kinase BB isoenzyme levels by radioimmunoassay in patients with neurological disease
Authors: Bell Rodney D. , Rosenberg Roger N. , Ting Ruby , Mukherjee Amal , Stone Marvin J. , Willerson James T.
Published: December 2004

Creatine kinase BB (CK‐BB) isoenzyme was measured by radioimmunoassay in serum and in cerebrospinal fluid from 61 patients with various neurological disorders. Statistically significant elevations of CK‐BB isoenzyme in the serum were observed in patients with acute cerebrovascular accidents and in those with seizures and a prolonged alteration in level of consciousness. Statistically significant elevations of CK‐BB isoenzyme in the cerebrospinal fluid were also found in patients who had suffered acute cerebrovascular accidents. Some patients with central nervous system infections, acute demyelinating disease, certain drug overdoses, head trauma, and complex migraine also had elevations of serum and CSF CK‐BB isoenzyme. In 2 patients with elevations of CK‐BB isoenzyme, the elevations in serum occurred later than those detected in the cerebrospinal fluid.

If CK‐BB elevations determined by radioimmunoassay can be demonstrated to be quantitatively related to the extent of brain damage, then these determinations in conjunction with experimental animal models and newer radiological techniques should allow evaluation, in an objective and precise manner, of measures designed to decrease that damage.
McArdle disease: The mystery of reappearing phosphorylase activity in muscle culture—A fetal isoenzyme
Authors: Dimauro Salvatore , Arnold Susan , Miranda Armand , Rowland Lewis P.
Published: December 2004

To understand the apparently paradoxical appearance of phosphorylase in muscle cultured from patients with McArdle disease, the enzyme in muscle culture was studied immunologically and electrophoretically. Antibody against normal human muscle phosphorylase completely inhibited the enzyme activity of adult muscle, but it had no effect on phosphorylase activity of muscle cultures from normal individuals or patients with McArdle disease. Also, amounts of antibody that would completely inhibit phosphorylase in mature muscle left about 30% of the activity in muscle obtained from human fetus at four months' gestation.

Acrylamide‐disc and slab‐gel electrophoresis showed a single band of phosphorylase activity in adult muscle and two bands in fetal muscle. This suggested that at four months' gestation, both fetal and mature forms are present but that only the mature isoenzyme is inhibited by the antibody. The enzyme from cultured muscle gave only a single band, with the electrophoretic mobility of the fetal isoenzyme. These data suggest that phosphorylase activity in muscle cultured from patients with McArdle disease is due to a fetal isoenzyme whose genetic control is different from that of the mature enzyme.
Primary cerebral venous thrombosis in young adults: The diverse manifestations of an underrecognized disease
Authors: Averback P.
Published: December 2004

Primary cerebral venous thrombosis has a wide clinical and pathological spectrum, which has not been recognized. Seven cases of aseptic cerebral venous thrombosis (5 fatal) are discussed, with pathological study and literature review. Five patients ranged in age from 22 to 31 years. In 3 cases no discernible cause for thrombosis was found.

Novel features of these cases include: primary bilateral internal cerebral venous thrombosis; isolated thrombocytopenia; occurrence in the context of (1) ulcerative colitis plus oral contraceptive use, (2) a twin transfusion syndrome, and (3) presenting syndrome five years after mastectomy for carcinoma. Diagnosis and treatment are discussed, and it is suggested that a focal coagulopathy may be responsible for this underdiagnosed condition.
Normal CAT scans in craniopharyngioma
Authors: Volpe Bruce T. , Foley Kathleen M. , Howieson John
Published: December 2004

Three patients with symptoms of headache and vision loss had normal routine CAT scans, with and without injection of contrast medium, as their initial diagnostic procedure. Subsequent pneumoencephalography revealed large suprasellar masses, which at operation were found to be partially cystic craniopharyngiomas. The findings emphasize the existence of craniopharyngiomas that are isodense with brain and may not be detected on routine CAT scan. When a patient's clinical presentation suggests chiasmal or sellar abnormalities, the pneumoencephalogram remains the most accurate diagnostic procedure.
What hope for repair of the brain?
Authors: Raisman Geoffrey
Published: December 2004

The consequences of axonal injuries in the adult nervous system depend on the location of the axons: complete anatomical and functional repair can occur in the peripheral but not the central nervous sytem. A quantitative electron microscopical comparison of the reactions to axonal injuries in a peripheral site (the superior cervical sympathetic ganglion) and in a central site (the septal nuclei) in adult rats shows that in both cases the denervated postsynaptic sites are reinnervated by new formation of synapses. However, in the ganglion it is the originally severed axons which form the new synapses (regeneration), whereas in the septum the new synapses arise from local, undamaged axons and the cut axons do not reestablish their original contacts. Failure of regeneration in the central site is probably due to the fact that the growing axon sprouts are incapable of finding a pathway to the denervated tissues. Since the observations indicate that the neuropil of the central nervous system is capable of highly efficient synapse formation after injury, true repair of central nervous sytem damage might be possible if methods could be devised for dealing with the “pathway” problem.
Carotid and vertebral‐basilar transient ischemic attacks: Effect of anticoagulants, hypertension, and cardiac disorders on survival and stroke occurrence— A population study
Authors: Whisnant Jack P. , Niall E. F. Cartlidge , Elveback Lila R.
Published: December 2004

A population of 199 patients from Rochester, MN, was followed from the time of their first carotid or vertebralbasilar transient ischemic attack(TIA). Patients treated with anticoagulants had no significant difference in survival from untreated patients. Among patients with carotid TIA who received anticoagulants, the net probability of stroke was slightly but not significantly lower than in untreated patients. The difference favoring treated patients with vertebral‐basilar TIA was significant starting at three months.

The rate of intracranial hemorrhage was higher among all patients receiving anticoagulant treatment than among untreated patients and was significantly higher among those 55 to 74 years old. Almost all the hemorrhages occurred after a year or more of anticoagulant treatment and in patients more than 65 years old.

Patients with high diastolic blood pressure had a significantly higher net probability of stroke than did patients with lower blood pressure and those receiving antihypertensive drugs. By implication, treatment of hypertension was effective in preventing stroke in patients with TIA.

Linear discriminant analysis and actuarial analysis indicated that diastolic blood pressure and anticoagulant therapy were the only factors that influenced stroke occurrence. There was no suggestion that previous myocardial infarction, angina pectoris, valvular heart disease, cardiac arrhythmia, or congestive heart failure–individually or in combination–influenced the occurrence of stroke or survival.
Dopamine binding following prolonged haloperidol pretreament
Authors: Hitri Ana , Weiner William J. , Borison Richard L. , Diamond Bruce I. , Nausieda Paul A. , Klawans Harold L.
Published: December 2004

The number of binding sites for tritiated dopamine as well as well as the affinity of 3H‐dopamine for dopamine receptors was studied in rats chronically pretreated with the neuroleptic haloperidol. The rats were given haloperidol for 14 or 21 days and were killed on day 21. It was found that 14 days of haloperidol pretreatment followed by drug withdrawal resulted in a 67% increase in the number of 3H‐dopamine binding sites in the striatum and a ninefold increase in the affinity constant in the striatum. The same pretreatment regimen had no effect on either the number of receptor sites or the affinity constant in the nucleus accumbens. These results are consistent with the hypothesis that chronic neuroleptic pretreatment results in receptor site hypersensitivity in the striatum, which may be a major factor in the production of tardive dyskinesia.
The effects of single‐dose alternate‐day prednisone therapy on the immunological status of patients with neuromuscular diseases
Authors: Cook J. D. , Trotter J. L. , Engel W. K. , Sciabbarrasi J. S.
Published: December 2004

Several immunological variables were examined in patients receiving high‐single‐dose, alternate‐day prednisone therapy for neuromuscular diseases. Dose‐dependent leukocytosis, lymphopenia, and monocytopenia occurred which were maximal 6 hours after prednisone administration but returned to control levels by the 24‐hour point. The lymphopenia involved T‐cells, B‐cells, and null cells, with the T‐cells most affected. Plasma cortisol levels and lymphocyte transformation in response to mitogens were also transiently and reversibly suppressed. There was a persistent decrease in serum IgG. Lymphocyte transformation was also suppressed when normal lymphocytes were incubated with treated patient sera or when treated patient lymphocytes were incubated in autologous pretreatment sera. The suppression factor was not removed from the lymphocytes by extensive washing. Patients whose disease responded to the high‐single‐dose, alternate‐day prednisone regimen were indistinguishable from nonresponders by the immunological responses measured.
Congenital sensory neuropathy with selective loss of small myelinated fibers
Authors: Low P. A. , Burke W. J. , McLeod J. G.
Published: December 2004

The results of clinical, electrophysiological, autonomic, and histopathological studies in a 6‐year‐old patient with congenital sensory neuropathy are presented. Selective loss of pain perception affecting the extremities was noted from infancy. Nerve conduction studies were normal. Small myelinated fibers were selectively reduced in the sural nerve, and unmyelinated fibers were normal.
Anomalies of motor development in hyperactive boys
Authors: Denckla Martha Bridge , Rudel Rita G.
Published: December 2004

Forty‐eight boys who scored high on rating scales for the “hyperactive syndrome” but who went without traditional neurological signs of learning disabilities were compared with 50 control boys on coordination tests. Discriminant function scores for speed, rhythm, and overflow correctly classified 89% of the boys as those with “hyperactive” versus “normal” behavioral histories. Thus, neurological examination of “hyperactive” boys does reveal developmentally immature coordination.
A double‐blind comparison of levodopa, madopa, and sinemet in Parkinson disease
Authors: Diamond Shirley G. , Markham Charles H. , Treciokas Leo J.
Published: December 2004

A sixteen‐week study examined the effect of Madopa and Sinemet on patients with Parkinson disease suffering nausea or vomiting as side‐effects of levodopa therapy and compared the efficacy of the three preparations in controlling the symptoms of Parkinson disease. Following a control period on levodopa, 20 patients underwent four consecutive four‐week regimens as follows: (1) double‐blind, in which a randomized half received levodopa and half received Madopa; (2) single‐blind, in which all received Madopa; (3) double‐blind, in which a re‐randomized half received Madopa and half Sinemet; and (4) single‐blind, in which all received Sinemet. Levodopa administration via Sinemet and Madopa was held to a fixed 20% of prior levodopa dosage.

Almost all patients showed great reduction in nausea and vomiting with both Madopa and Sinemet. Seventy percent of the patients showed improvement in disability compared to their levodopa baseline levels. Group means showed no difference between the improvement seen on Madopa and that seen on Sinemet. However, examination of individual responses showed that the majority of patients fared distinctly better on either Sinemet or Madopa.
Clinical variation in 2 related children with neuronopathic Gaucher disease
Authors: Grover Warren D. , Tucker Samuel H. , Wenger David A.
Published: December 2004

The clinical features in 2 second cousins with neuronopathic Gaucher disease include slowly progressive ataxia, spasticity, myoclonus, and seizures with relative preservation of intellectual function. Organomegaly was noted only in Patient 1. Both patients had diffuse slowing with paroxysmal features in electroencephalograms and a deficiency of β‐glucosidase activity in leukocytes and skin fibroblast cultures. The parents of Patient 1 and the related father of Patient 2 had levels of β‐glucosidase activity consistent with the carrier state for Gaucher disease. The value of β‐glucosidase activity in the mother of Patient 2 suggests a different mutation, the result being a defective enzyme component not detectable by measuring total activity.
Salt effects on the conformation of α‐poly‐L‐glutamic acid
Authors: Jacobson A. L.
Published: December 2004

The optical rotatory dispersion in the range 630–340 mμ has been measured for aqueous solutions of the tetramethylammonium salt of α‐poly‐L‐glutamic acid to compare the effects produced by added tetramethylammonium chloride and magnesium chloride at equivalent ionic strengths. The addition of magnesium chloride significantly decreased the apparent pK of the α‐poly‐L‐glutamic acid. This large decrease in apparent pK makes the use of pH inadequate as a rough criterion of polymer conformation. Both the Moffitt b0 and the modified Drude constants λc have been calculated to compare helix content in presence and absence of divalent cation. Both estimations of helix content show the same trends with increased polymer ionization. At equivalent polymer ionization the divalent cation caused a significant increase in the helix content in the helix‐coil transition region.
Electrophoresis of the nucleic acids
Authors: Olivera Baldomero M. , Baine Peter , Davidson Norman
Published: December 2004

A zone electrophoresis apparatus using ultraviolet, optics has been constructed to study nucleic acids at concentration less than 0.004%. Native DNA has a mobility about 15% higher than denatured DNA over a range of conditions of pH and ionic strength. DNA's from different sources have closely similar mobilities. A study of a molecular weight series of DNA indicates that the mobility is constant in the molecular weight range of 2.5 × 105 to 1.3 × 108. DNA mobilities change in the expected way with pH but the fractional change in mobility is less than the change in charge calculated by titration curves. A small decrease in mobility accompanies an increase in ionic strength. RNA's from various sources have mobilities slightly lower than denatured DNA except for s‐RNA which travels slightly faster.
Anomalous rotatory dispersion of metachromatic mucopolysaccharide‐dye complexes. I. Heparin
Authors: Stone Audrey Larack
Published: December 2004

Optical rotatory dispersion measurements on metachromatic heparin:dye complexes have revealed Cotton effects in the absorption region of the hound dye which are dependent upon the “native” integrity of the heparin molecule and upon the dye to site ratio, that is, the dye array. According to the recent ideas concerning induced Cotton effects in external chromophores hound to helical polymers, heparin, a mucopolysaccharide, appears to exhibit helical secondary structure.
The adsorption of polyribonucleotides
Authors: Winsten Walter A.
Published: December 2004

Using a chromatographic technique, the adsorption of the polyribonucleotides s‐RNA and poly‐A provided with tri‐n‐butylammonium ions from an aqueous solution on to the surface of polymeric hydrocarbon granules has been demonstrated. The aqueous solution from which adsorption takes place is the aqueous phase which results on agitating together n‐butanol (100), water (130), tri‐n‐butylamine (10), n‐butyl ether (10), and glacial acetic acid (2.5) (parts by volume). Microporous polyethylene granules, microporous fluorinated polyethylene granules, and solid grains of polyethylene powder have been employed as adsorbents. The adsorbed polyribonucleotides could be eluted by aqueous solutions of sodium chloride, urea, or triethylammonium acetate. s‐RXA with tri‐n‐butylammonium counterions could also be adsorbed on polymethacrylic acid in tri‐n‐butylammonium form and eluted therefrom with aqueous urea solutions. It is considered that the adsorption from aqueous solution of polyribonucleotides with tri‐n‐butylammonium counterions on polymeric hydrocarbon surfaces is mediated by hydrophobic bond formation. Van der Waals forces may also contribute to the bonding. It is suggested that studies on the adsorption of polynucleotides provided with counterions: possessing nonpolar groups at an aqueous solution‐polymeric hydrocarbon interlace may permit the elaboration of experimental systems to serve as models for the evaluation of the role of hydrophobic and van der Waals bonding forces in the interaction of polynucleotides with cell membrane surfaces.
Bifunctional reagents and protein structure determination. The reaction of phenolic disulfonyl chlorides with lysozyme
Authors: Herzig David J. , Rees Allan W. , Day Richard A.
Published: December 2004

It was established that phenol‐2,4‐disulfonyl chloride and α‐naphthol‐2, 4‐disulfonyl chloride introduce new intramolecular or tertiary bonds into lysozyme. The phenolic hydroxyl group seems to make the cross linking reagents soluble in aqueous media; it was established that a sulfonylating; species does dissolve prior to hydrolysis but that the chlorosulfonyl groups are hydrolyzed within seconds of dissolution. New covalently linked residues were shown to be introduced by different, spectra. Peptide maps of the lysozyme treated with phenol‐2,4‐disulfonyl chloride. peroxidized, and digested with trypsin showed definite deletions and additions when compared with the control. Partial analysis of the peptides showed that cross linking between ε‐amino groups of lysine residues had occurred. A certain degree of stabilization of lysozyme to inactivation by certain inactivating conditions was noted after treatment with the two reagents. Ultra‐centrifugal analysis of the lysozyme treated with phenol‐2,4‐disulfonyl chloride showed that there was no detectable fraction having a higher molecular weight than native lysozyme. Tentative assignments of positions of cross linking were made.
Chain regularity and flow dichroism of deoxyribonucleic acids in solution
Authors: Wada Akiyoshi
Published: December 2004

Deoxyribonucleic acids (DNA's) extracted from several biological sources have been studied by means of the flow dichroism method, using the transparent coaxial cylinder apparatus. This study has two purposes: (1) to make clear the hydrodynamic behavior of the DNA chain, and the regularity in the orientation of purine and phrimidine bases about the molecular axis; and (2) to develop this particular flow dichroism method as an established device for the study of chain regularity of DNA and other chain polymers. The velocity gradient dependence of dichroism agrees well, to a first approximation, with the behavior of a model of a hydrodynamically equivalent ellipsoid in revolution. Differences between theoretical and empirical curves have been tentatively ascribed to the flexibility of the chain under consideration. Two kinds of data, 1 lie rotary diffusion coefficient and internal dichroism, have been evaluated by a graphical device in which the double logarithmic plots of reduced dichroism and velocity gradient of flow are compared with the theoretical curve. The data obtained have shown good reproducibility for DNA samples prepared by the same method from the same biological source. However, a remarkable difference in internal dichroism and rotary diffusion constant has been observed between DNA groups of different biological origin. The difference may be caused by fragmentation of DNA during the deproteinization procedure, bill the possibility that some of these differences originate in the biological source of the DNA cannot be denied. Orientation of purine and phrimidine bases in aqueous solution is found to be quite regular in direction, as predicted by the Watson–Crick model. Dichroic spectra have shown that the direction of the oscillator dipole corresponding to the 260 mμ absorption band has a different angular relationship to the helical axis than the oscillator dipole for the 220 mμ band.
The renaturation of deoxyribonucleic acids. I. Rates of bimolecular reactions of complementary and noncomplementary Gaussian chains
Authors: Wada Akiyoshi , Yamagami Hiroko
Published: December 2004

The mechanism of the renaturation of DNA molecules is examined on the basis of the bimolecular interaction of Gaussian chain polymers. In the nucleus formation by hydrogen bonding in segment–segment interaction, two types of interchain interaction, that is, one between complementary chains and one between noncomplementary chains, and one noncomplementary intrachain interaction are considered to be, in competition. Several previously observed characteristics of the renaturation process are displayed by this simple model. In particular it accounts for the dependence of the extent of renaturation on the heterogeneity, molecular weight, and radius of gyration of DNA, and of the ratios of the reaction rates between complementary and noncomplementary segments. Among these variables the ratio of reaction rates has shown to have a quite specific value, as high as the order of 104, which favors the complementary‐strand interaction. This very great bias in favor of complementary strand interaction emphasizes that the renaturation phenomena displays the same character of biological specificity that is associated with enzyme–substrate interaction or antigen–antibody interaction. Moreover, since DNA is a good example of a one‐dimensional system, it seems to provide a suitable clue for pursuing the analysis of pattern recognition at the macromolecular level.
The role of the σ‐framework in the properties of the biological purines and pyrimidines: dipole moments and tautomeric equilibria
Authors: Berthod Hélène , Pullman Alberte
Published: December 2004

Del Re's method for the study of saturated compounds has been adapted so as to deal with the σ‐framework of conjugated molecules. This modified procedure is used in evaluating the σ‐contribution to the dipole moments of the nucleic bases and of the A‐T and G‐C base pairs and also to the free energy change in the tautomeric, equilibria of the bases. Associated with an appropriate Hückel method for evaluating the π‐contribution, the results obtained predict a small resultant moment for A‐T versus a large moment for G‐C. The energy calculations predict the keto and amino forms of the bases to be the most stable forms and cytosine to be the most easily involved in tautomeric shift to the rare form.
Statistical mechanics of noncovalent bonds in polyamino acids. VII. Fluorescence as an indication of conformation
Authors: Poland Douglas C. , Scheraga Harold A.
Published: December 2004

It is shown how the technique of fluorescence may be used to assess conclusions about conformation which are based on a statistical mechanical treatment of simple protein models. Specifically, the state of bonding and distance between two chromophores in a molecule depend on the overall conformation, which can be computed for model systems. On the assumption that the intensity and polarization of fluorescence are affected by exciton transfer between the chromophores, it is possible to compute the effect of conformation on fluorescence. It is demonstrated that the conformational changes computed in the preceding paper will give rise to marked changes in the intensity and polarization of fluorescence.
Band‐forming centerpieces for the analytical ultracentrifuge
Authors: Vinograd Jerome , Radloff Roger , Bruner Robert
Published: December 2004

Three types of band‐forming centerpieces useful in band centrifugation in the analytical ultracentrifuge are described. The mode of filling and the advantages and disadvantages of each type are discussed.
Physical properties of periodate‐oxidized amylose: Aggregation of oxidized amylose in aqueous solutions
Authors: Erlander Stig R. , Griffin H. L. , Senti F. R.
Published: December 2004

The ability of periodate‐oxidized amylose to form aggregates in aqueous solution was studied by sedimentation, light scattering, and viscosity analyses. Ultracentrifuge schlieren patterns show that aggregation can be appreciable at pH 3.0 and 1.0. The hydroxyl ion‐catalyzed degradation of the oxidized amylose is faster at pH 3.0 than at pH 1.0. Viscosity and sedimentation analyses conducted at pH 3.0 show that a minimum in the degree of aggregation of the oxidized molecules is obtained at 15–25% oxidation. Solubulity studies and x‐ray diffraction patterns on retrograded amylose show that maximum solubility of the retrograded amylose is obtained by oxidizing to the extent of 25–35%. It was therefore concluded that in the general range of 20–30% periodate oxidation, the oxidized amylose has a minimum ability to form intermolecular hydrogen bonds. Outside of this range, oxidized amylose readily forms aggregates in aqueous solutions.
Optical rotatory dispersion of egg proteins. I. Ovalbumin, conalbumin, ovomucoid, and lysozyme
Authors: Tomimatsu Yoshio , Gaffield William
Published: December 2004

Optical rotatory dispersions (ORD) of ovalbumin, conalbumin, ovomucoid, and lysozyme (muramidase) were measured in aqueous solution over a wavelength range of 195–600 mμ. The dispersion curves obeyed a one‐term Drude equation above 300 mμ. The strong Cotton effects in the ultraviolet showed peaks and troughs at about the same wavelength for all four proteins, but the crossover point for the 225 mμ Cotton effect for ovomucoid was appreciably lower than for the other proteins. Helical contents calculated by using the Moffitt equation, the trough value of the 225 mμ Cotton effect, and the expressions for helical content recently proposed by Schechter and Blout ranged from 5 to 34%. Except for ovomucoid, the trough value of the 225 mμ Cotton effect gave the lowest helical content.
Optical rotatory dispersion of poly‐L‐tyrosine in solution
Authors: Pao Yoh‐Han , Longworth Ruskin , Kornegay R. L.
Published: December 2004

This paper consists of a theoretical discussion of exciton band contributions to the optical rotatory dispersion of polypeptides in a specific context, namely that of poly‐L‐tyrosine in solution in α‐helix form. The calculated results when compared with existing data suggest that poly‐L‐tyrosine in aqueous solution at pH < 11.2 as studied by Fasman et al. and Beychok et al. is of right‐handed α‐helix conformation. Poly‐β‐L‐aspartate esters on the other hand are shown definitely to be of left‐handed conformation. Although there are undoubtedly interactions between neighboring side groups there is no evidence in optical rotatory dispersion data of existence of a stable helical arrangement of the side groups in poly‐L‐tyrosine. The NV1 exciton contributions below 1900 A. should provide reliable measures of the helix content and handed ness of the helix in polypeptides, and experimental techniques for the wavelengths below 1900 A. should be developed.
Molecular weight distribution of polymers of γ‐benzyl‐L‐glutamate
Authors: Scoffone Ernesto , Peggion Evaristo , Cosani Alessandro , Terbojevich Maria
Published: December 2004

The molecular weight distribution of poly‐γ‐benzyl‐L‐glutamate prepared by N‐carboxy anhydride (NCA) polymerization with the use of di‐n‐butylamine, diisopropylamine, and sodium methoxide as initiators was investigated. In every case, narrow distributions were found. Moreover the results allow us to conclude that the same polymerization mechanism is operative with each of the above initiators. The experimental distribution curves show fairly good agreement with the theoretical distributions expected for a polymerization process without termination.
Tritium–hydrogen exchange of poly‐L‐glutamic acid in aqueous solutions
Authors: Ikegami Akira , Yamamoto Sadaaki , Oosawa Fumio
Published: December 2004

To investigate the flexibility or motility of the secondary structure of poly‐L‐glutamic acid, a simple model molecule of proteins, the kinetics of the tritium–hydrogen exchange of this polymer in aqueous solutions was followed at various pH values by use of a freeze‐drying technique and a liquid scintillation counter. The most essential point of the experimental results is that all of the protons (or isotopes) attached to peptide nitrogens were exchanged according to a simple first‐order reaction and the rate was proportional to the fraction of random coil conformation determined by optical rotatory dispersion measurements. This means that the tritium attached to a peptide unit is exchangeable with a proton in water only when this unit is contained in the random coil structure and that the interchange of each unit between helical and random coil conformations takes place as a result of thermal fluctuation at very high frequency, although the average helical content of each molecule has a definite value.
X‐ray diffraction studies of the conformation of polymer molecules in solution. II. Poly‐3,5‐dibromotyrosine
Authors: Brady George W. , Salovey R. , Reddy J. M.
Published: December 2004

X‐ray diffraction patterns from dilute solutions of poly‐3,5‐dibromo‐L‐tyrosine in dimethylformamide and equivalent concentrations of 2,6‐dibromophenol in the same solvent are compared. The intensity difference as a function of scattering angle is indicative of the arrangement of residues in the polymer. A novel averaging procedure is used to compute the intensity patterns arising from regular arrays of bromine atoms. Interbromine spacings measured on a Drieding model of a right‐handed α‐helix with side groups restricted to rigid positions of maximum stagger give moderate agreement with experiment. Very good agreement with observations is obtained by allowing for a small oscillation of phenyl rings which effectively cancels out the contribution of large distances to the intensity curve.
Kinetics of synthesis and/or conformational changes of biological macromolecules
Authors: Pipkin A. C. , Gibbs J. H.
Published: December 2004

The analogy, in both the thermodynamics and the kinetics, of reversible polymerizations on templates (in the case wherein these are catalyzed by exoenzymes) to helix–coil transitions (in the case where these proceed only from one end of each macromolecular chain) is presented. A suggestion, based on this analogy, is made concerning the possible nature of biological control of synthesis of macromolecules (enzyme induction and repression). The equations governing the kinetics of these one‐dimensional cooperative processes are presented and their solutions discussed.
Neighbor–neighbor interactions in single‐strand polynucleotides: Optical rotatory dispersion studies of the ribonucleotide ApApCp
Authors: Vournaki John N. , Scheraga Harold A. , Rushizky George W. , Sober Herbert A.
Published: December 2004

The neighbor–neighbor interactions in the small ribotrinucleotide ApApCp were investigated with the aid of optical rotatory dispersion measurements. This trinucleotide shows a Cotton effect between 220 and 325 mμ, in the region of its maximum ultraviolet absorption. The specific rotation of the trinucleotide is independent of concentration while the magnitude of the Cotton effect (levorotation) decreases markedly with increasing temperature. Such effects were not observed with the component nucleotides alone, in a simulated hydrolysis mixture, nor with the hydrolyzed trinucleotide. The Cotton effect is attributed to perturbation of the nucleotide base chromophores by neighbor–neighbor intramolecular interaction (stacking), without any hydrogen bonding being involved; this interaction decreases with increasing temperature because of increased internal rotational freedom about the single bonds of the backbone chain with an accompanying disruption of the neighbor–neighbor interaction between the bases. This explanation is supported by a statistical mechanical theory of neighbor‐neighbor interactions in polynucleotides, involving the forces between the bases. Application of this technique to further studies of polynucleotides and polypeptides is discussed.
Specific interactions in proteins due to proton fluctuations
Authors: Timasheff S. N.
Published: December 2004

A theory of site–site interaction due to proton/charge fluctuations in protein molecules has been developed. It is shown that, with the proper geometric configuration of identical ionizable groups on matching sites, a specific attraction may be established. This attractive force has a bell‐shaped pH dependence and is maximal close to the pK of the groups involved. Various types of protein interactions are examined in the light of this theory.
Extrinsic cotton effects of aminoacridines bound to DNA
Authors: Blake A. , Peacocke A. R.
Published: December 2004

The optical rotatory dispersion curves of the proflavine cation were measured in the spectral range 400–500 mμ. No optical activity was observed for the free cation but a large positive Cotton effect appeared in the presence of DNA. The effect of ionic strength, denaturation of the DNA, and the DNA/proflavine ratio were studied. The dependence of the magnitude of the Cotton effect on the DNA/proflavine ratio suggests that a nearest‐neighbor interaction between bound proflavine molecules is necessary for optical activity. A simple statistical treatment was made which indicated that only a small number of proflavine molecules are required in close proximity for optical activity to occur. Denaturation of the DNA did not destroy the optical activity, which shows that long runs of DNA double helix are not necessary for optical activity of the ligand molecules. The optical rotatory dispersion curves of acridine orange which was bound to DNA were also measured. Two Cotton effects of opposite sense could be distinguished, the relative magnitudes of which depended on the DNA/acridine orange ratio and the state of denaturation of the DNA. The apparent differences from the proflavine‐DNA system can to a large extent be explained in terms of the tendency of acridine orange to form aggregates.
Studies of the helix–coil transition of poly‐L‐lysine in film and solution
Authors: Noguchi Hajime
Published: December 2004

Water‐insoluble films of poly‐L‐lysine, crosslinked with formaldehyde, were suspended in aqueous media and their relative lengths measured as a function of pH. A sharp transition of the polymer was observed in the pH range which corresponded with that observed in polylysine solutions by optical rotation or dilatometry. In NaBr and NaCl solutions the coiled form of the polylysine film shrinks with increasing salt concentration, but in NaHCO3 solution the extent of the contraction is larger, and the coil–helix transition of polylysine occurs at lower pH when NaHCO3 is added to the medium. If one assumes the formation of amino carbamate in this case, this phenomenon can be well explained. Urea does break up the hydrogen bonds in helical polylysine film, but not completely. This result is interesting compared with that obtained for poly(L‐glutamic acid). After the coil–helix transition region was found by film experiments, the volume change associated with the coil‐to‐helix transition was measured and found to be about 1–l.5 ml. per amino residue after taking electrostatic interaction into consideration. This value is nearly same as that obtained for poly(L‐glutamic acid). By contrast, the value for poly‐γ‐benzyl‐L‐glutamate was reported to be −0.077 ml./mole of repeating unit. So it is still necessary to determine the magnitude and direction of the volume change for various kinds of polypeptides.
Conformations and interactions of excited states. II. Polystyrene, polypeptides, and proteins
Authors: Longworth J. W.
Published: December 2004

Previous fluorescence and phosphorescence studies of aromatic model compounds have been extended to polymers: “atactic” and isotactic polystyrene, seven aromatic poly‐(amino acids), and two proteins. We have confirmed previous observations that both forms of polystyrene exhibit strong excimer fluorescence emission at room temperature but not at 77°K. Of the poly(amino acids) (all observed in helix‐supporting solvents), poly‐L‐phenylalanine, poly(α‐benzyl‐L‐aspartic acid), and poly‐1‐benzyl‐L‐histidine likewise show excimer emission at room temperature but not at 77°K., while poly‐L‐tyrosine, poly‐L‐tryptophan, poly(γ‐benzyl‐L‐glutamic acid), and poly‐S‐benzyl‐L‐cysteine exhibit no excimer emission at either temperature. The aromatic residues of bovine serum albumin exhibit only “normal” fluorescence, but, lysozyme appears to be unique among proteins in showing excimer‐like tryptophan emission in the native state; its luminescence becomes “normal” upon denaturation. It appears very probable that none of these polymers has a ground‐state conformation in which the aromatic groups have face‐to‐face orientations appropriate for excimer interaction. It is concluded that at room temperature absorption of light can cause local “melting” of regular (usually helical) structures and thus, in some polymers, permit the attainment of a face‐to‐face arrangement of aromatic rings within the radiative lifetime of their excited singlet states. In certain other polymers (for reasons not clear at present), and in all polymers at 77°K., this does not occur. This concept is extended to provide a bettor basis for understanding the mechanism of formation of the photodimer of thy mine in irradiated DNA.
Some aspects of stereochemistry and hydrogen bonding of carbohydrates related to polysaccharide conformations
Authors: Sundaralingam M.
Published: December 2004

Some general rules governing hydrogen bonding at the ring oxygens of furanosides, pyranosides, and bridge oxygens of glycosides have been formulated from existing data on crystal structures of carbohydrates. Ring oxygens of the majority of the glycopyranosides in the hemiacetal or acetal form are involved in hydrogen bonding such that the hydrogen bond direction is usually equatorial to the ring plane and not axial. In contrast, there are no known examples of ring oxygens of glycofuranosides and methyl‐glycopyranosides displaying hydrogen bonding in the crystal. Also, the bridge oxygens of glycosides are not involved in hydrogen bonding. The observed shortening in the exocyclic and endocyclic anomeric C(1)O bonds and the geminal CO bonds indicate that compounds with two oxygen atoms attached to the same saturated carbon atom may participate in double‐bond‐no‐bond resonance interaction in the same manner as difluoromethane. It is also possible that under these circumstances the carbon atom exhibits greater than tetracovalency. The “anomeric effect” may also be related to (a) the differences in the “double bonding” or bond shortening in the anomeric CO bonds of the anomeric glycopyranosides, (b) the shorter intramolecular O(1)…︁O(5) non‐bonded interaction, and (c) the smaller O(1)C(1)O(5) valence angle in the equatorial anomer compared to the axial anomer. An analysis has been made of the energetically preferred conformations about the glycosyl and glycosidic bonds of 1,4‐ and 1,3‐polysuc‐charides. In the 1a, 4e‐glycopyranosides the projected angle ϕ1 [O(5)C(1)OR, where R = C or H] is positive, while it is negative in the 1e, 4e‐glycopyranosides. Angle ϕ2 [C(1)OC(4′)C(3′)] is positive in both the 1,4‐anomeric polyglycosides. 1e, 4e‐ and 1a, 4e ‐polysaccharides are stabilized by intramolecular O(5)…︁HO(3′) and O(2′)…︁O(3′) hydrogen bonding, respectively, and generate linear and helical (cyclic) structures, respectively. 1e, 3e‐ and 1a, 3e‐polysaccharides may be stablized by one of two possible intramolecular hydrogen‐bonding schemes such that the 1a, 3e ‐polysaccharides generate helical structures while the 1a, 3e‐polysaccharides generate nonhelical structures. The conformation about the C(5)C(6) bond in the pyranosides falls into two groups where the angle ϕ00 [O(5)C(5)C(6)O(6)] is either positive, ∼+60 ± 30°, or negative, ∼–60 ± 30°, the former conformation being found more frequently. In the furanosides the latter conformation is preferred.