bluuebunny/crossref_metadata_2025 huggingface dataset:
Depression in Alzheimer's disease: Phenomenological features and association with severity and progression of cognitive and functional impairment
Authors: Haupt Martin , Kurz Alexander , Greifenhagen Annette
Published: December 2004

Seventy‐eight outpatients with a clinical diagnosis of dementia in Alzheimer's disease according to the ICD‐10 draft research criteria were investigated with annual evaluations over a period of 2 years to study the phenomenology and association with severity and progression of cognitive and functional impairment of depression in Alzheimer's disease. As measured by the Dementia Mood Assesment Scale (DMAS), depressive symptoms occurred frequently, such as decrease in motor activity, lack of responsiveness, agitation and depressed appearance. Multiple stepwise regression demonstrated that decrease in motor activity and lack of responsiveness were the strongest contributors to an association of depressive symptoms with severity of cognitive and functional impairment. The global score of the DMAS mood subscale was not related to dementia severity. There was no relation between depressive symptoms in Alzheimer's disease and the rate of cognitive and functional decline within a 12‐month and 24‐month observational period. Our results suggest that depressive symptoms are frequent concomitants of dementia in Alzheimer's disease. Depressive symptoms are in part associated with a greater severity of cognitive and functional impairment in Alzheimer's disease. However, depressive symptoms, unlike other non‐cognitive psychopathological symptoms, for example psychotic phenomena, are not prognostically relevant with respect to a lower or higher rate of symptom progression.
The prevalence and phenomenology of psychotic symptoms in dementia sufferers
Authors: Ballard C. G. , Saad K. , Patel A. , Gahir M. , Solis M. , Coope B. , Wilcock G.
Published: December 2004

One hundred patients referred to old age psychiatry services in the West Midlands and 25 patients referred to a memory clinic in Bristol with mild to moderate dementia were assessed using the GMS/HAS schedule together with a detailed inventory to assess their psychotic symptoms. On careful evaluation one patient did not have dementia. Eighty‐three of the other 124 patients (66.9%) had at least one psychotic symptom. The prevalence of psychotic symptoms in the patients from the West Midlands and from the memory clinic in Bristol were extremely similar. Thirty‐five per cent had at least one visual hallucination, 12.9% had at least one auditory hallucination, 48.4% had at least one delusional belief and 29.0% had at least one delusional misperception. Most individuals experienced their psychotic symptoms at a frequency between weekly and daily. Twenty‐four had no insight into their psychotic symptoms and acted upon them, while only one patient had full insight into their symptoms. Thirty‐seven subjects were mildly distressed and 14 were severely distressed by the psychotic symptoms they experienced. There was a trend for patients with cortical Lewy body dementia to be more likely to have psychotic symptoms than patients with Alzheimer's disease or vascular dementia. The symptom profile of psychotic symptoms in the different dementias was, however, very similar. The frequencies of individual psychotic symptoms are described in the text.
Nurses' experiences of strain and their reactions in the care of severely demented patients
Authors: Hallberg Ingalill R. , Norberg Astrid
Published: December 2004

All nurses (N = 132) on the wards specializing in the care of the demented within a municipality were given two scales to assess their view of common patient actions and how easy they thought those actions were to deal with in the care situation, and to assess their emotional reactions during the provision of care. Also the Maslach burnout Inventory (MBI) and the Work Related Strain Inventory (WRSI) were used to test concurrent validity. Based on principal component analysis, the nurses' view of patient actions resulted in being agitated, unruly, living empty lives, being peaceful, dependent, non‐responsive and cooperative, and the nurses' view of difficulties in dealing with patient actions revealed ability to manage deprivation, agitation, desertedness, wilfulness, peacefulness and cooperation. A three‐factor solution was chosen for the emotional reactions: feelings of devotion—rejection, association—dissociation and usefulness—uselessness. Agitated and dependent patient actions were found to be most common while agitation and desertedness were regarded as most difficult. Patient seen as agitated and living empty lives related to the provision of care being difficult while dependence related to care as being easy to provide. Thus the findings gave further support to the belief that viewing the patient's life as meaningful as well as being able to develop a cooperative nurse‐patient relationship is crucial for nurses' experience of strain. Thus support should be directed towards achieving this kind of relationship.
Citation patterns in the International Journal of Geriatric Psychiatry: Cultural ethnocentrism revisited?
Authors: Barak Yoram , Philpot Michael , Levy Raymond
Published: December 2004

The country/region of origin of all original papers appearing in the International Journal of Psychiatry (IJGP) during the first 9 years of its publication was recorded. A more detailed analysis of citation patterns was carried out on the 105 original articles published during 1992. The results indicated that 50–60% of the articles emanated from the United Kingdom but that in general authors cited a broad range of specialities from journals published around the world. North American authors tended to cite North American sources more frequently than did their counterparts from other countries. There was evidence that the impact of the IJGP is increasing despite its omission from some scientific reference databases.
Clinical characteristics of resistant depression in the elderly
Authors: Bonner D. , Howard R.
Published: December 2004

The case notes of 30 patients who had responded to treatment for a depressive episode and 29 patients who were considered to be resistant to treatment were examined retrospectively. ‘Treatment resistance’ was associated with an onset of depression before the age of 50, the presence of hypochondrical features and the presence of cognitive impairment. Those patients considered to be resistant to treatment were also significantly less likely to be given ECT, more likely to be taking benzodiazepines and to spend significantly more time in hospital. These findings are discussed.
Remote depressions of cerebral metabolism in hemiparetic stroke: Topography and relation to motor and somatosensory functions
Authors: Seitz Rüdiger J. , Schlaug Gottfried , Kleinschmidt Andreas , Knorr Uwe , Nebeling Bruno , Wirrwar Andreas , Steinmetz Helmuth , Benecke Reiner , Freund Hans‐Joachim
Published: December 2004

Depressions of regional cerebral glucose metabolism (rCMRGlu) as measured with positron emission tomography in 28 patients with first hemiparetic stroke were mapped anatomically and related to the involvement of the cortico‐spinal tract and the somatosensory pathway. Cortico‐spinal tract and somatosensory pathway status were examined by magnetic evoked motor potentials (MEP) and somatosensory evoked potentials (SSEP), respectively. Patients were grouped with respect to the stroke lesions as assessed by magnetic resonance images into striatocapsular, thalamocapsular, and corticosubcortical groups. In spite of identical clinical presentation, the topography of significant remote rCMRGlu depressions varied in the affected cerebral hemisphere among the three groups, involving also the contralateral hemisphere in the thalamocapsular and cortico‐subcortical group. The thalamus was the only area with a significant mean rCMRGlu depression in all groups, although it was structurally spared in striatocapsular and cortico‐subcortical strokes. The remote rCMRGlu depressions in the primary sensorimotor cortex were associated with significantly abnormal MEPs in striatocapsular stroke, while both the MEPs and SSEPs were significantly abnormal in the cortico‐subcortical group. Further, depressed rCMRGlu in the putamen of the lesion side and in the cerebellar hemisphere ipsilateral to the hemiparesis correlated with motor impairment. Our data suggest that, in addition to damage of the efferent cortico‐spinal or afferent somatosensory tract, impairment of other circuits may contribute to the severe hemiparesis initially observed after stroke. We hypothesize that the chronic remote rCMRGlu depressions described in the present study result from axonal damage interfering with connectivity patterns. © 1994 Wiley‐Liss, Inc.
Human brain atlas: For high‐resolution functional and anatomical mapping
Authors: Roland P. E. , Graufelds C. J. , Wǎhlin J. , Ingelman L. , Andersson M. , Ledberg A. , Pedersen J. , Åkerman S. , Dabringhaus A. , Zilles K.
Published: December 2004

We present the new computerized Human Brain Atlas (HBA) for anatomical and functional mapping studies of the human brain. The HBA is based on many high‐resolution magnetic resonance images of normal subjects and provides continuous updating of the mean shape and position of anatomical structures of the human brain. The structures are transformable by linear and nonlinear global and local transformations applied anywhere in 3‐D pictures to fit the anatomical structures of individual brains, which, by reformatting, are transformed into a high‐resolution standard anatomical format. The power of the HBA to reduce anatomical variations was evaluated on a randomized selection of anatomical landmarks in brains of 27 young normal male volunteers who were different from those on whom the standard brain was selected. The HBA, even when based only on standard brain surface and central structures, reduced interindividual anatomical variance to the level of the variance in structure position between the right and left hemisphere in individual brains. © 1994 Wiley‐Liss, Inc.
Chloracylierung und Bromacylierung von Carbonylverbindungen. IV. Bildungsmechanismus von Carbonsäure‐(1‐halogenalkyl)estern
Authors: Bigler Peter , Neuenschwander Markus
Published: December 2004

Chloroacylation and bromoacylation of carbonyl compounds IV. Investigations of the reaction mechanism

The kinetics of the Lewis acid catalyzed reaction between acyl chlorides and carbonyl compounds (especially aldehydes) is investigated by 1H‐NMR.‐spectroscopy. With acetyl chloride as starting material a second order reaction is observed; the rate of the reaction increases in polar solvents as well as with increasing electron‐donating capacity of the aldehyde. ‐ With benzoyl chloride as starting material the reaction is first order with respect to benzoyl chloride, but zero order with respect to the aldehyde. The reaction rate is strongly influenced by the substituents of the benzoyl chloride. ‐ Two polar reaction mechanisms which are in accord with these results are outlined and discussed.
Nucleoside und Nucleotide, Teil 12. Synthese von Dinucleosidmonophosphaten mit 1‐(2′‐Desoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyrimidon als Baustein
Authors: Volz Ernst , Tamm Christoph
Published: December 2004

Nucleosides and Nucleotides. Part 12. Synthesis of Dinucleoside Monophosphates Containing 1‐(2′‐Deoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyrimidone

The connexion of the modified nucleoside 1‐(2′‐deoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyrimidone (Md, 2) with the natural nucleotides pTd and pGd is described. The protected dinucleoside monophosphates (MeOTr)MdpTd (6) and (MeOTr)MdpG (9) were prepared by the standard phosphodiester method using DCC as condensing agent. MdpTd (7) was obtained by treatment of 6 with formic acid/methanol 7 : 3 at 0° 9 was converted to the free dinucleoside monophosphate MdpGd (11) by removing the N‐isobutyryl‐ and p‐methoxytrityl protecting group on consecutive treatment with 0.04N CH3ONa in CH3OH and HCOOH/CH3OH 7:3 at 0° respectively. Enzymatic degradation of the free dinucleoside of the free dinucleoside monophosphates 7 and 11 yielded the corresponding nucleosides and nucleotides in the correct ratios.
The dexamethasone suppression test as a predictor of response to desipramine
Authors: Bielski Robert J. , West Charles L. , Shafer Christine L. , Holmes Gregory H.
Published: December 2004

Thirty‐four endogenously depressed outpatients were treated with desipramine following dexamethasone suppression tests (DSTs). When mean change scores on the Hamilton scale were compared between DST‐suppressors and non‐suppressors there was a clear trend toward more favourable response in the non‐suppressors. However, this finding fell just short of reaching statistical significance. Ten out of 13 DST‐non‐suppressors (77 per cent) responded to desipramine, while 10 out of 21 suppressors (48 per cent) responded. This difference was not significant.
Urinary kallikrein excretion after DDAVP during lithium treatment
Authors: Waller D. G. , Campbell S. K. , Albano J. D. M.
Published: December 2004

Several factors are believed to contribute to impaired responsiveness to arginine vasopressin (AVP) during lithium treatment. The renal kallikrein–kinin system is reported to antagonize the renal effects of AVP in vitro but there are no reports of its activity during lithium treatment. Urinary active kallikrein excretion in 18 lithium‐treated patients was found to be lower than that in eight healthy volunteers. Following intravenous administration of an AVP analogue, des‐amino‐D‐arginine‐vasopressin, to the lithium‐treated patients, the urinary excretion of active kallikrein was unchanged, despite an impaired urine‐concentrating ability. These results suggest that stimulation of renal kallikrein does not contribute to inhibition of the action of AVP, and thus the genesis of nephrogenic diabetes insipidus during lithium treatment.
Signal detection analysis of information processing in patients receiving prophylactic lithium therapy
Authors: Johnson F. Neil
Published: December 2004

There are numerous indications in the literature that lithium may affect the processing of sensory information, but no work involving human subjects has provided a direct test of this hypothesis. The present study attempted to provide such a demonstration by carrying out a signal detection analysis of information processing in a number of subjects undergoing prophylactic treatment with lithium. It was found that lithium impaired information processing in accordance with the hypothesis. In addition, efficiency of information processing was directly related to a global clinical rating of mood state, providing further evidence in support of an information processing model of manic‐depressive illness. A relationship also noted between mood state and response bias suggested that there may be two quite distinct psychological mechanisms underlying affective dysfunction, and that these might relate to the lithium responder‐non‐responder dichotomy.
Sublingual lormetazepam in the treatment of sleep disorders in general practice patients
Authors: Sastre‐Y‐Hernandez M. , Visser P. , Schütt B. , Fichte K.
Published: December 2004

The sublingual form of the benzodiazepine hypnotic lormetazepam was developed with the aim of attaining greater flexibility in the treatment of sleep disorders. The object is to achieve rapid onset of hypnotic effect and provide patients with a form of medication which they can take after having gone to bed and only if they have difficulty in falling asleep. In a placebo‐controlled crossover double‐blind study the hypnotic effect, side‐effects and acceptance of lormetazepam sublingual (1 mg) were investigated in 60 patients with sleep disorders receiving treatment from physicians in independent practices. The study was conducted over a total of 2 weeks, the patients receiving lormetazepam and placebo for 7 days respectively, changing over in the second week. The results show that in the sublingual form lormetazepam (1) is distinctly better than placebo as regards hypnotic efficacy, particularly with respect to the reduction of sleep latency; (2) does not lead to a significantly higher rate of concomitant symptoms than placebo; and (3) is well accepted by the patientsin the wafer form.
Cilobamine in the treatment of atypical depression
Authors: Wager Steven , Quitkin Frederic , Stewart Jonathan , McGrath Patrick , Harrison Wilma , Markowitz Jeffrey , Tricamo Elaine
Published: December 2004

Sixteen patients meeting our criteria for atypical depression were treated in a 7‐week single‐blind pilot study with cilobamine mesylate, an investigational antidepressant structurally distinct from tricyclic antidepressants (TCA) and monoamine oxidase inhibitors (MAOI). Nine patients (56 per cent) responded to cilobamine. Cilobamine patients were compared with a group of similar patients receiving placebo for 6 weeks in a separate double‐blind study. The response rate to cilobamine was superior to that of placebo. Cilobamine patients also showed significantly greater improvement in Hamilton Depression Scale scores than did placebo patients. Previous studies have demonstrated the efficacy of MAOIs in atypical depression. This study suggests that certain antidepressants which are not MAOIs, and are free of dietary restrictions and the risk of hypertensive crises, may also be effective in atypical depression.
Antidepressant drugs given repeatedly increase the behavioural effects of methoxamine
Authors: Maj J. , Rogóz̊ Z. , Skuza G.
Published: December 2004

In this study we investigated the effect of imipramine, citalopram and mianserin on behavioural effects of methoxamine, an α1‐adrenoceptor agonist, in the rat. Methoxamine (25 and 50 m̈g) given into the brain lateral ventricle, increases the exploratory activity assessed in the open field test (time of walking, ambulatory activity, rearing + peeping). The studied antidepressants, administered repeatedly (10 mg/kg p.o., twice daily, 14 days) but not in single doses, enhance the above effects of methoxamine. The results provide further arguments for the hypothesis that antidepressant drugs administered repeatedly induce a functional α1‐adrenoceptor up‐regulation.
Controlled comparison of milnacipran (F2207) 200 mg and amitriptyline in endogenous depressive inpatients
Authors: Ansseau M. , Von Frenckell R. , Papart P. , Mertens C. , De Wilde J. , Botte L. , Devoitille J.‐M. , Evrard J.‐L. , De Nayer A. , Koch‐Bourdouxhe S. , Darimont P. , Lecoq A. , Mirel J. , Couzinier J. P. , Demarez J.‐P. , Serre C.
Published: December 2004

A multicentre study compared the antidepressant efficacy and the tolerance of milnacipran (200 mg/d) and amitriptyline (150 mg/d) in two parallel groups of 43 major depressive inpatients, endogenous subtype, as defined by Research Diagnostic Criteria. The duration of the study was 4 weeks, with weekly assessments by means of the Montgomery and Asberg depression scale (MADS), the Hamilton depression scale, the Clinical Global Impressions (CGI) and a checklist of symptoms and side‐effects. Results showed similar improvement in both groups but better tolerance with milnacipran (less drowsiness and anticholinergic side‐effects), reflected in the better scores on the therapeutic index of the CGI. The clinical profile of the two drugs was somewhat different with more transitory sedation with amitriptyline and more improvement in concentration difficulties with milnacipran during the first weeks of the study associated with more effect on retardation with milnacipran at the end of the study.
Desglycinamide‐(Arg8)‐vasopressin in five trials with memory‐disturbed patients
Authors: Hijman R. , Jolles J. , Verhoeven W. M. A. , van Ree J. M. , Elderson A. , de Wied D.
Published: December 2004

A series of five consecutive clinical trials were performed in which the neuropeptide desglycinamide‐(Arg8)‐vasopressin (DGAVP) was administered to human subjects suffering from cognitive and memory complaints. The patients selected for the study were carefully screened with the aid of neuropsychological assessment procedures. The trials were conducted according to a structured design in which the variables ‘dose’, ‘route of administration’, ‘treatment schedule’, ‘diagnostic group’, and ‘severity of deficit’ were varied from trial to trial in order to find optimal conditions for the possible expression of a peptide effect. The results indicate a statistically significant effect of DGAVP on word list learning in patients with mild brain trauma, suggesting that learning performance and memory retrieval are improved after peptide treatment in these patients. Patients with more severe brain trauma did not respond to peptide treatment. Some DGAVP effects, e.g. increased speed of memory search, were observed in patients with age‐associated memory deficits.
Drug‐induced creutzfeldt‐jakob like syndrome: A review
Authors: Fear Christopher F.
Published: December 2004

Creutzfeldt‐Jakob disease is an untreatable degenerative disorder which presents problems in diagnosis. The clinical picture is said to be characterised by dementia, myoclonus and periodic triphasic discharge on the electroencephalogram. The high profile given to this disorder recently will lead inevitably to more diagnoses being made. There have been reports of a syndrome identical to CJD which is due to psychotropic drugs, particularly lithium, and which resolves spontaneously on discontinuation of the responsible medication. The available reports of this syndrome are reviewed and consideration is given to its validity and possible mechanisms by which it may be produced.
Plasma noradrenaline, adrenaline and DHPG responses to clonidine in control and depressed subjects
Authors: Healy D. , Paykel E. S. , White W. , Whitehouse A. M. , Ashby M. , Brown M. , Theodorou A. E. , Lawrence K. M. , Horton R. W.
Published: December 2004

Plasma noradrenaline, adrenaline and DHPG were measured in depressed and control subjects before and after a challenge test with clonidine 1.3 μg/kg. Significant falls in all three variables were found, but there were no differences between the two groups on either baseline or post‐challenge test values. No correlation was found between these catecholamine responses to clonidine and clonidine‐induced changes in growth hormone, blood pressure, or pulse rate. There were also no correlations between plasma catecholamine levels and platelet adrenergic receptor binding or plasma cortisol. These findings do not support the hypothesis of a generalized adrenergic deficit in major depressive disorder.
The effect of inositol on lithium‐induced polyuria—polydipsia in rats and humans
Authors: Bersudsky Y. , Vinnitsky I. , Grisaru N. , Yaroslavsky U. , Gheorghiu S. , Ivgi D. , Kofman O. , Belmaker R. H.
Published: December 2004

It has been proposed that lithium acts by inhibiting inositol monophosphatase, thereby lowering tissue inositol levels. We therefore studied inositol effects on a prominent lithium side‐effect, polyuria—polydipsia, in rats and in humans. Rats were treated with daily injections i.p. LiCl for 14 days and were given 2.5 per cent inositol, 2.5 per cent mannitol or no additive in their drinking water. Fourteen patients complaining of lithium side‐effects were recruited for the study after approval by the Helsinki Committee. Patients were treated with inositol in 500 mg capsules, two capsules three times daily for 5 days. In both experiments inositol ameliorated Li‐induced polyuria—polydipsia. However, mannitol had similar but less powerful and perhaps less lasting effects in rats.
Changes of lymphocyte beta‐adrenergic receptors and platelet serotonin reuptake sites in aging and dementias
Authors: Rozza A. , Scavini C. , Steardo L. , Guaita A. , Favalli L. , Racagni G. , Brunello N.
Published: December 2004

We have studied the kinetic constants of β;‐adrenergic receptors in lymphocytes and of serotonin uptake sites in platelets from adult and elderly volunteers and from aged patients with a diagnosis of multi‐infarct dementia (MID) or senile dementia of Alzheimer's type (SDAT). The results showed that in the physiological aging process, β;‐adrenergic receptor density is reduced and 5HT transport system is enhanced. MID is associated to a loss of β;‐adrenoceptor affinity and a slight increase in the capacity of 5HT uptake. The kinetic constants of both β;‐adrenergic receptors in lymphocytes and 5HT uptake sites in platelets from SDAT patients were comparable to those observed in the adult population, being thus different from those found in the aged matched volunteers.

These changes could be interpreted as resulting from compensatory mechanisms that replaced altered plasma monoamine concentrations. The apparent absence of such changes in SDAT patients could suggest the lack of these compensatory effects.
Neuroleptic malignant syndrome associated with the use of risperidone, an atypical antipsychotic agent
Authors: Lee Heidi , Ryan James , Mullett George , Lawlor Brian A.
Published: December 2004

Neuroleptic malignant syndrome (NMS) is a rare and sometimes fatal adverse reaction to neuroleptic drugs. Atypical antipsychotic agents, such as risperidone, are thought to be less likely to cause NMS because of their pharmacological profile. This is a case report of NMS associated with risperidone treatment.
The effect of tryptophan on brain 5‐HT function: A review
Authors: Cowen P. J.
Published: December 2004

Administration of l‐tryptophan (TRP), the amino acid precursor of 5‐hydroxytryptamine (5‐HT), to animals increases brain 5‐HT synthesis and in some circumstances, the release of 5‐HT in terminal fields. TRP also appears to increase brain 5‐HT neurotransmission in humans because neuroendocrine studies have shown that intravenous TRP produces a dose‐related increase in plasma prolactin concentration, probably via indirect stimulation of postsynaptic 5‐HT1A receptors. The effect of TRP on prolactin release in humans is enhanced by several effective antidepressant treatments including tricyclic antidepressants, selective 5‐HT re‐uptake inhibitors, monoamine oxidase inhibitors and lithium. The ability of these drugs to augment the effect of TRP on brain 5‐HT function may represent the pharmacological mechanism that underpins the utility of TRP in combination drug treatments of refractory depression.
Some problems concerning the assessment of arterial prosthetic materials
Authors: Wesolowski Sigmund A.
Published: December 2004

The problems with the experimental and clinical assessment of arterial prosthetic materals vary from species‐transfer of data to vested interests once an implantale device has been perfected for human trail. In spite of all the problems which arise, there has been a steady increase in our knowledge of the basic healing pattern of implanted arterial prostheses and the elaboration of specific paths for improvement of prosthetic design. Further development will be linked closely to the active participation of the biomedical researcher in areas of biophysical and bioengineering investigations.
Geordnete Kristallisation. Nucleation und Mineralisation
Authors: Thiele Heinrich
Published: December 2004

1. With the help of ionotropic gels it is possible to duplicate native structures consisting of two materials, one of them the matrix. 2. Counter‐ions combined with the ionic groups on the ordered polyelectrolytes can be exchanged. With certain counter‐ions an insoluble, crystalline precipitate is formed immediately after the ion‐exchange process as an ordered reaction product, i.e., nucleation. 3. Ionotropic gels were crosslinked through the secondary hydroxyl groups (uronic acid residuals) in such a way that the rate of ion exchange was only slightly lower, that no great shrinkage resulted, and that the pores remained free of extraneous polymers. 4. The microscopic structure of ionotropic gels can be divided into (a) a part with secondary structure with micellar particles and hollow pores and (b) a part with tertiary structure with lamellae and isopores. 5. On crystallization in shrunken gels the crystals enter into the tertiary structure—both intracapillary as well as interlamellar—due to spatial reasons. 6. Through control of the shrinkage of the gels, one can regulate the way in which the ordered crystals enter into the two structures. 7. One can change the size of the crystallites by variation of the degree of crosslinking. The higher the degree of crosslinking, the smaller the crystallite. 8. By treatment with waves of ions one can increase the solid content of the gel to values from 50 to 70%. One obtains gels with a mechanical strength like that of bones, teeth, shells, or pearls. The phenomenon of intramicellar crystallization is reversible. Monovalent counter‐ions, as well as H‐ions, dissolve and extract the included secondary substance. One then obtains the original crosslinked gel. 10. The gel has always to be formed first. Without the ordered base structure (matrix) one obtains unordered crystallites such as occur in the chalklike fields of the pearl shells.
Studies on the stability and protein adsorption characteristics of heparinized polymer surfaces by radioisotope labeling techniques
Authors: Falb R. D. , Takahashi M. T. , Grode G. A. , Leininger R. I.
Published: December 2004

A series of studies were performed using S35‐labeled heparin to determine the amount and the permanancy of heparin grafted onto nonthrombogenic surfaces. The calculated thicknesses of the heparin layers (based on geometrical areas) ranged from 100 to 1500 A. It was shown that the surface having a 100‐A layer of attached heparin was nonthrombogenic. The stability of the heparin attached to polypropylene, silicone rubber, hydrin rubber, and graphite–benzalkonium‐heparin (GBH) surfaces in distilled water, isotonic saline, and human plasma was measured. The results showed that after exposure to water and saline, the first three surfaces retained most of the attached heparin (>90%) in contrast to the GBH surface which retained only 31%. After contact with human plasma for 3 hr at 37°C, polypropylene retained 32% and GBH surfaces 19% of the heparin which was initially present. In another series of experiments, the adsorption of P32‐labeled proteins onto unheparinized, quaternary ammonium, and heparinized surfaces was measured. The results indicated that the amounts of albumin, Hageman factor, thrombin, and γ‐globulin adsorbed onto heparinized surfaces were equal to or greater than the amounts adsorbed onto unheparinized surfaces. The implications of this in terms of the nonthrombogenicity of the heparinized surfaces are discussed.
Materials and design consideration for a compact artificial kidney
Authors: Levine Sumner N. , LaCourse William C.
Published: December 2004

A design theory is developed for a compact artificial kidney utilizing microcapsules containing urease, ion exchange resin, and adsorbents for uric acid and creatinine. It is shown that the critical factor is the permeability property of the microcapsule wall and that an artificial kidney 10 cm in length and 2 cm in diameter is feasible.
The diffusion of urea through porous glass
Authors: Altug I. , Hair M. L.
Published: December 2004

Work on the rates of diffusion of urea through two different types of porous glass is reported and compared with data obtained using a commercial cellophane membrane from an artificial kidney. The results show that the rate of urea diffusion per unit area through the larger pored glass can be 3–4 times higher than through the cellophane membrane.
Thrombogenicity of some biomedical materials: Platelet‐interface reactions
Authors: Mason Reginald G. , Scarborough D. Emerson , Saba Sabiha R. , Brinkhous Kenneth M. , Ikenberry Lynn D. , Kearney James J. , Clark Howard G.
Published: December 2004

Fifty‐eight polymers and other materials were evaluated for compatibility with human blood in an in vitro test system. Assays for platelet factor 3 activation, activation of the coagulation sequences, and release of hemoglobin and adenine nucleotides were performed on blood exposed to each of the 58 test materials. Of the materials tested, collagen, heparinized hydrin rubber, poly (methyl methacrylate), graphite‐benzalkonium‐heparin, poly (methyl acrylate), isotactic poly(methyl methacrylate), grafted poly (ethylene oxide) on poly (acrylic acid), balata rubber, L‐1624 from 3M Co., and chlorinated poly (vinyl chloride) appeared most compatible with blood. Chemical affinities appeared to have little to do with blood compatibility of the materials tested. Electron microscopic examination of blood components adherent to selected test materials following exposure to blood was carried out. Each of the three polymers with “good” and the two polymers with “poor” blood compatibility characteristics which were examined by electron microscopy was coated with a thin unilaminar adsorbate from blood. Platelets and fibrin were focally deposited on this adsorbate. Of the test surfaces examined, only glass was covered by a trilaminar adsorbate. Mechanisms of formation of the adsorbates are discussed.
Composite hydrophilic materials suggested by a simple model of cartilage. I
Authors: Flam Eric , Schubert Maxwell , Kapfer William H. , Brenner Walter
Published: December 2004

Sedimentation of collagen or cellulose fibers freshly precipitated from aqueous solutions containing certain soluble, flexible polyelectrolytes compacts them to pellets which may incorporate considerable amounts of the polyelectrolyte. The amount of polyelectrolyte incorporated increases with its chain weight and with its concentration in the solution from which the fibers were precipitated. The amount of water held by the pellets after compaction under a standard set of conditions generally increases with the amount of polyelectrolyte which has been incorporated into the pellet. Pellets formed by the compaction of cellulose fibers in the presence of polyelectrolyte are coherent although those formed in the absence of polyelectrolyte are not; all collagen pellets are coherent. All coherent pellets can be dried and, subsequently, reconstituted by being soaked in.15 M KCl. Reconstituted collagen pellets hold over two times as much water as the initial wet pellet formed by compaction; reconstituted cellulose pellets hold on the average about ⅓ the amount of water as the initially compacted pellets. The reconstituted pellets can again be dried and reconstituted with generally little further loss of polyelectrolyte or change in capacity to take up water.
The search for the nonthrombogenic property of colloidal graphite
Authors: Milligan Herbert L. , Davis Janover W. , Edmarkm K. William
Published: December 2004

The nonthrombogenic property of the graphite‐Benzalkonium‐heparin surface has not been consistently attained by those using this coating. In addition, there is mounting evidence that this property is not dependent entirely on the presence of heparin. A series of tests were conducted to further define the properties of colloidal graphite materials, methods of control and possible relationships to thrombus formation. These tests included electrokinetic investigations, dielectric measurements and other physical/chemical property evaluations. It was found that the colloidal graphite coating approximates many properties which are characteristic of animal tissue. However, considerable scatter in the duplication of these properties was encountered. The properties which seemed to separate the Acheson Colloids Company DAG‐35 coating from other graphite products were those of porosity and permeability. Control of these parameters may be critical to achieving consistent uniform success.
A testing device for evaluation of gas transfer through synthetic membranes
Authors: Lautier André , Laurent Daniel , Granger Alain , Sausse André
Published: December 2004

An experimental set‐up was designed to allow the determination of the gas transfer rates between human blood and pure O2 through a synthetic membrane. This device permitted the obtention of known steady states. It consisted of a thermostated closed blood loop containing a capillary oxygenating cell with a functional area of 400 cm2. The thickness of the blood film in the capillaries was about 150 μ. The type of membrane under study consisted of a supporting cellulosic paper, impregnated with a silicone elastomer. The manufacturing process allowed to get reproduceable hydrophobic microporous membranes without selective permeability in gas to gas phase. The continuous evaluation of the “expired” CO2 flow rate was achieved with an accurate titration method. O2 and CO2 transfer rates were also determined on the blood phase. In parallel mounting of two oxygenators permitted an intercomparison of membranes. The results gained from this study permitted to consider one of these membranes (6.5 g silicone/m2) as suitable for incorporation into a blood oxygenator. Moreover, agitation of the blood capillaries at a suitable frequency resulted in a substantial increase of O2 and CO2 transfer rates.
Corrosion effects of three sterilization methods on experimental implant surfaces
Authors: Sandrik J. L. , Wragg L. E.
Published: December 2004

Autoclave sterilization of paper‐wrapped stainless steel implants resulted in slight general surface corrosion and crystalline contamination. Such artifacts may produce microanodes which induce local tissue reactions, thereby lowering the pH and further activating the corrosion process. Implants sterilized in ethylene oxide or benzalkonium chloride did not show artifact corrosion or contamination. Mechanisms are presented to show the effects contaminants have upon both the corrosion behavior and the tissue reaction of implant materials.
Parameters affecting preparation of nylon‐based hemodialysis membranes
Authors: Luttinger Manfred , Cooper C. W.
Published: December 2004

Nylon‐based membranes of greater dialyzing capacity than Cuprophan have been prepared by solution casting. Good permeability is being achieved by the use of diluents such as dimethylsulfoxide in the casting solution. Modifying resins, primarily epoxies, contribute to higher permeability, good aging stability, and heat‐sealing properties. Drying time between film casting and water immersion as well as the temperature and composition of the immersion bath are important factors in membrane performance. Methods for attaching heparin to the film surface have been developed, thus imparting good blood compatibility to the membranes.
Preliminary evaluation of porous metal surfaced titanium for orthopedic implants
Authors: Hahn H. , Palich W.
Published: December 2004

Recent results indicate varying degrees of bone ingrowth into porous metal and ceramic bodies. Such homogeneously porous ceramic and metal implants generally possess inadequate mechanical properties, limiting their application to low stress or nonstructural applications. An experiment was performed wherein titanium porous coatings were applied to a wrought titanium bone implant. These surfaces were achieved by plasma spraying of titanium hydride powder, depositing a mixture of wellbonded titanium‐titanium oxide with pore diameters varying from .002 to .005 in.

Implant specimens were placed in sheep femora for periods of 14 and 26 weeks. No adverse affects were noted. Interface shear strengths were determined by torque tests which indicated approximately a twenty‐fold increase over similar tests performed on uncoated control specimens.
The in vivo antithrombogenicity of waxed surfaces
Authors: Whiffen James D. , Whiffen John R.
Published: December 2004

The naturally occurring waxes possess rather marked in vivo antithrombogenic properties, which are related both to the material and the polishing process.
Amino acid polymers for biomedical applications. I. Permeability properties of L‐leucine DL‐methionine copolymers
Authors: Martin E. C. , May P. D. , McMahon W. A.
Published: December 2004

A series of DL‐methionine/L‐leucine copolymers was prepared from the coresponding N‐carboxy‐anhydrides. The copolymers formed clear flexible films having low water vapor transmission rates. Peroxide oxidation of the pendant methyl‐theioethyl groups to methyl‐sulfinoethyl groups enhanced the hydrophilic properties of the membranes, and the water vapor transmission rates rapidly increased with an increase in the number of pendant methyl‐sulfinoethyl groups. Increasing the leucine content of the membranes produced a 13‐fold increase in the carbon dioxide permeability and a 6‐fold increase in oxygen permeability, whereas, an increase in the methionine content doubled the carbon dioxide‐oxygen separation factor.

Synthetic poly (α‐amino acids) are very similar to naturally occurring proteins with respect to composition and conformation. Because of these similarities, they are being considered in aerosol spray bandages, synthetic skin applications and as coatings for plastic prostheses. The unusual permeability characteristics of the DL‐methionine/L‐leucine copolymers make them interesting membranes for possible use in artificial kidney machines and blood oxygenators.
Transport properties of a new dialysis membrane
Authors: Brauman Sharon K. , Fritzinger Bruce K.
Published: December 2004

The dialysis and flow properties of a selected copolymer system, consisting of polyethylene terephthalate and polyoxyethylene glycol, have been studied in some detail. Such transport information should serve as a guideline to future development of improved, synthetic, hemodialysis membrane materials. By varying the size of the polyoxyethylene glycol segment, the transport properties of this copolymer have been examined as a function of the chemical and physical properties of the system. Membrane transport has been described by three flow parameters: the filtration, reflection, and solute permeability coefficients. Data for three copolyether‐ester compositions and several aqueous solutes are discussed and compared with data on cuprophane, the cellulose material currently used in the Kiil hemodialyser.
Hollow fiber membrane oxygenator
Authors: Skiens W. E. , Lipps B. J. , Clark M. E. , McLain E. A.
Published: December 2004

Hollow fibers have been produced and evaluated for use as membrane oxygenators in an artificial heart device. Gas permeable capillaries now commercially available are unsuitable for this use because of: (1) low percent open cross‐sectional area, (2) large internal diameter, and (3) high cost. A number of polymers were initially selected for evaluation because of their reported high gas permeabilities. Those selected include a number of rubbers of various compositions, certain poly‐α‐olefins and an experimental thermoplastic silicone rubber copolymer. These materials were first evaluated as flat membranes (films) for their gas permeabilities and also for ease of preparation in hollow fiber form. Hollow fibers were prepared from the most promising of those studied, poly‐4‐methylpentene‐1 and the thermoplastic polydimethylsiloxane copolymer. Fibers, ranging in the size from 30 to 300 μ ID, were spun with open cross‐sectional areas of 40‐65%. Oxygen and carbon dioxide permeabilities measured on these fibers were compared to that of Silastic

Dow Corning medical grade poly (dimethylsiloxane).

rubber membranes. These permeabilities range from 1/20 that of Silastic rubber for unmodified poly‐4‐methylpentene‐1 to 2/3 for the thermoplastic silicone copolymer. Modification of poly‐4‐methylpentene‐1 has made it possible to increase it's permeability by tenfold, while still maintaining physical properties necessary to spin and fabricate this material.
Compatibility of porous ceramics with soft tissue; application to tracheal prostheses
Authors: Hulbert S. F. , Morrison S. J. , Klawitter J. J.
Published: December 2004

The trachea is a rather simple structure, and partly because of this simplicity, many attempts have been made to effect replacement with various types of prosthetic tubes. Unfortunately, the basic design of the trachea is not easily duplicated, and thus far there is no completely satisfactory prosthetic replacement. A series of porous and non‐porous ceramics implanted in muscle tissue of rabbits indicated that rigid, porous materials can be compatible with soft, viable tissue. A prosthesis of porous ceramic rings and alternate bands of Dacron mesh was constructed and employed to bridge 6‐cm defects created in the tracheas of mongrel dogs. After 6 months an asymptomatic animal was sacrificed. Firm fixation was accomplished and the lumen was completely patent, but histological sections demonstrated that ingrowth and scarring did not satisfactorily contain bacterial infection. Encouragement of epithelial regeneration or some artificial barrier is necessary for successful implants. Work in progress includes devices using both methods to provide this barrier.
The use of ceramics in augmentation and replacement of portions of the mandible
Authors: Topazian Richard G. , Hammer Wade B. , Talbert Christian D. , Hulbert Samuel F.
Published: December 2004

Mandibular form and structrue are critically important in outlining the lower face and providing anchorage for the lower teeth. Mandibular function is also essential for mastication. Destruction and deformity of the mandible may, therefore, be crippling both physically and psychologically. The usual problems affecting the mandible are reduction in the substance of the alveolar ridge through inflammation or atrophy, presence of small bone gaps resulting from non‐union of fractures and avulsive injuries, neoplasia, and existance of contour deficiencies. The procedures necessary to deal with these problems are: (1) augmentation of the deficient mandibular alveolar ridge, (2) replacement of small discontinuity defects of the mandible, (3) replacement of large portions of mandible, and (4) correction of deficiencies in the contour of the mandible. Bone grafts, metals, and medical polymers have been widely used in the treatment of bony defects but these materials have serious shortcomings, particularly with reference to host acceptance and inertness. Additionally, soft tissue and bone seldom attach firmly to these materials. The ceramics appear to offer many advantages over materials used earlier. Calcium aluminate ceramic prostheses with interconnecting pores in the 150 to 200‐μ range were implanted in dogs to correct a variety of mandibular deficiences. They show considerable promise as an implant material.
The role of the porcelain inlay in restorative dentistry
Authors: Myerson Richard L. , Dogon I. L.
Published: December 2004

Porcelain inlays coupled by a silane treatment to composite resins which were used as cementing media and in turn retained by an undercut were evaluated as to their marginal integrity and retention against conventionally restored teeth. These included restorations in teeth with undercuts of resins, composites, and porcelain inlays cemented with zinc oxyphosphate cements.

The evaluations were determined by isotope penetration during thermal cycling (180 cycles from 12 to 50°C), scanning electron microscopy of sectioned restorations, and mechanical pull tests.

The results showed improved retentive qualities and markedly improved resistance to marginal penetration. Improved adaptation of the composite to the tooth surface was produced by the mechanical action of seating the porcelain inlay.
Factors influencing longevity of low‐profile prosthetic heart valves
Authors: Boretos John W. , Detmer Don E. , Braunwald Nina S.
Published: December 2004

Abrasion and performance of artificial heart valves are related to geometrical configuration, blood flow dynamics, manufacturing techniques, and interaction of materials. Incidence of thromboembolism, valve insufficiency, and shortened longevity are critically dependent upon these factors. The effect of construction parameters on valve performance is discussed in general terms and illustrated from in vivo experience with a specific low‐profile design.