123rc/medical_text huggingface dataset:
Compensatory mechanisms in degenerative neurologic diseases. Insights from parkinsonism. In animal models of parkinsonism, the ability to lose a substantial proportion of dopaminergic neurons without behavioral deficits does not derive from other systems taking over function of the dopaminergic pathway. The surviving nigrostriatal projection increases both the rate of synthesis and the release of dopamine, as compensatory adjustments. This capacity allows at least a fivefold rise in dopamine delivery per neuron, and this enhancement is potentiated further by receptor up-regulation. Decreased reuptake, due to loss of nerve endings, may also lead to augmented occupancy of dopamine receptors, and so constitute yet another compensatory mechanism. In humans, positron emission tomography has revealed subclinical impairment of the dopaminergic nigrostriatal pathway in subjects at risk for parkinsonism caused by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and Lytico-Bodig (the amyotrophic lateral sclerosis-parkinsonism dementia complex of Guam). However, the separation of patients with clinically overt idiopathic parkinsonism from controls is less marked in vivo (by positron emission tomography) than in postmortem analysis (by neurochemical assay). This disparity may be attributable to the reduction in the number of nigrostriatal nerve endings, leading, in vivo, to a relative increase of extracellular dopamine because active reuptake into the nerve endings is an important mechanism for removing dopamine from the synaptic cleft. In contrast, in a postmortem setting, dopamine that is not sequestered in the storage vesicles of nerve endings is readily available for biochemical degradation during the interval between death and brain analysis. Finally, it is also possible that differences may derive, in part, from dissimilar kinetic systems for handling exogenous and endogenous levodopa.
Circulatory and thermal adjustments to prolonged exercise in paraplegic women. The circulatory and thermal responses to 90 min of wheelchair ergometer exercise were examined in five wheelchair dependent (WD) women with low level spinal dysfunction and five able-bodied (AB) women who served as a comparison group. Metabolic rate during exercise was 221 W for WD and 255 W for AB (P greater than 0.05). Oral temperature (Tor), mean skin temperature (Tsk), oxygen uptake (VO2), heart rate (HR), and cardiac output (Qc) were assessed periodically throughout the exercise period. Ambient conditions were 24-25 degrees C and 38-52% relative humidity. A significant group X time interaction was found for Tor (P less than 0.001) and Tsk (P less than 0.001). Tor of the WD group steadily increased during the exercise, whereas the AB group showed a stable Tor. Tsk of WD increased rapidly during the first 5-10 min of exercise and continued to rise at a slower rate throughout the exercise. In contrast, Tsk of AB rose to a peak during the first 10 min and then showed a decreasing trend. VO2 and HR remained stable in both groups throughout the exercise period. Following an initial increase in Qc from minute 10 to minute 20 in both groups, values for WD continually decreased until Qc at 80 min was 14% lower than at 10 min. The findings suggest that the WD women had greater thermoregulatory strain than the AB women as indicated by a higher Tor and Tsk and by an inability to maintain Qc due to paralysis of the lower limbs and perhaps an increase in cutaneous blood volume.
Use of EMLA cream as an analgesic in the management of painful otitis externa. A new application of EMLA cream is described. Relief of pain in otitis externa is difficult and systemic analgesics for this localized condition are often ineffective. Meticulous cleaning of the external auditory meatus is an essential step in the treatment. EMLA cream is an effective analgesic which can be used to relieve pain and anaesthetize the external auditory meatus to allow cleaning in patients with intact tympanic membranes.
Proximal femoral allografts in revision hip arthroplasty. We followed prospectively 69 patients with 78 proximal femoral allografts performed for revision of total hip arthroplasty for an average of 36 months (range 29 to 68). Large fragment proximal femoral allografts and cortical strut allografts were successful in 85%. Grafts smaller than 3 cm in length (calcar grafts) were clinically successful in 81%, but 50% underwent significant radiographic resorption. We conclude that large proximal femoral allografts and cortical strut allografts provide dependable reconstruction of bone stock deficiencies during revision total hip arthroplasty.
Putative neuroexcitation in cerebral ischemia and brain injury. Involvement of neuroexcitatory mechanisms in cerebral ischemia and brain injury was explored in experimental models of repetitive forebrain ischemia by temporary occlusion of carotid arteries in gerbils and cryogenic injury to the cerebral cortex in rats and gerbils. Our observations in these models revealed a pattern of injury that involved some anatomic structures outside the areas of direct ischemic or traumatic insult. Such foci of injury revealed conspicuously abnormal uptake of 45Ca associated with slight or moderate neuronal alteration, whereas severely injured areas showed no 45Ca uptake. Electron microscopic observations revealed a characteristic presence of calcium in swollen dendrites, closely resembling pictures obtained in neuroexcitatory conditions such as epileptic seizures. Abnormal uptake of 45Ca was associated with apparent blood-brain barrier changes characterized by intracytoplasmic uptake of extravasated albumin into the neurons. Protein synthesis assayed by in vivo [3H]leucine incorporation was reduced in regions showing calcium accumulation. Our observations suggest that neuroexcitation may play an important role in development of secondary and chronic changes after ischemic or traumatic brain insults.
Determination of tissue viability in experimental electrical injuries. Electrical burns or ischemia (induced by vascular ligation) were produced in the legs of 15 anesthetized dogs to study evolution of tissue changes compared with impedance alterations. After the application of 1-ampere currents at 60 Hz, animals were monitored from 1 to 4 days. Muscle impendance was measured with frequency sweeping to determine tissue destruction. Nuclear magnetic resonance spectroscopy (phosphorus 31) was used to assess metabolic activity, and results were compared to impedance measurements. In burned limbs, 70% reduction in muscle impedance was seen, which corresponds to decreased metabolic activity (absent organic phosphates) and suggests necrosis. Visually viable tissue had impedance decreases of 25% and levels of organic phosphates slightly lower than normal. Relaxation frequencies in dogs with severe burns exceeded 80 kHz; in viable tissue, 30 to 40 kHz (normal: 30 kHz). In ischemic muscle, organic phosphates decreased rapidly (1 to 2 hours); impedance changes evolved more slowly (1 day), but they ultimately reached the same degree of severity. Measurement of impedance may be a valuable adjunct in the evaluation of electrical burns, since significant changes strongly suggest nonviability.
Microangiopathy in the eosinophilia-myalgia syndrome. The eosinophilia-myalgia syndrome associated with the ingestion of L-tryptophan was recognized in late 1989. We describe our pathologic study of skin, fascial, and muscle biopsies from 21 patients evaluated by light microscopy, histochemistry, and electron microscopy. A perivascular, lymphocytic infiltrate with eosinophils was present in the dermis, fascia, and skeletal muscle. Lymphocytic infiltration of arteries and arterioles was seen. Ultrastructurally, capillary and arteriolar endothelial cell thickening and necrosis was present. This microangiopathy suggests that ischemia may be a contributing factor to the findings in this syndrome.
Risk factors for gallstones among Chinese in Taiwan. A community sonographic survey. A health survey of adults aged 30 years or more was carried out in southwest Taiwan to determine the prevalence of gallstones and to study risk factors associated with gallstones. Blood samples were collected and abdominal sonographic examination and anthropometric measurements were performed on a total of 923 people. The 40 gallstone cases detected resulted in a prevalence of 4.3%. The risk factors explored included age, sex, hepatitis, obesity, hyperlipidemia, and diabetes mellitus (DM). Age and DM were the only significant factors associated with gallstones in our study. With a reference group of 30-39-year-olds as a comparison, multiple logistic regression analysis showed a trend effect with odds ratios of 1.73, 3.74, and 6.32 for age groups of 40-49, 50-59, and 60 or above, respectively. The odds ratio for DM was as high as 2.59. However, sex, body weight index, chronic hepatitis B, and hyperlipidemia were not significantly associated with gallstones.
Adenocarcinoma arising in a foregut cyst of the mediastinum. A case of malignant transformation in a mediastinal cyst of the esophageal reduplication type is presented. The cyst had been recognized 39 years previously, but remained asymptomatic until sudden growth occurred. It was resected totally from the esophagus and the patient recovered well. A review of the literature showed that malignancy in mediastinal foregut cysts is extremely rare.
Aspergillus terreus endophthalmitis in a patient with chronic lymphocytic leukemia. A 65-year-old woman with a 7-year history of chronic lymphocytic leukemia presented with acute visual loss, pain, and redness in her right eye. Results of stains and cultures of anterior chamber fluid were negative. Neurologic problems, bronchopulmonary pneumonia, recurrent skin lesions, and a low-grade fever developed. Progressive respiratory distress ensued, and the patient died 1 month after presentation. Cultures from antemortem sputum and skin samples were positive for Aspergillus terreus. Postmortem histologic results showed extensive A terreus invasion of the posterior vitreous, retina, choroid, and anterior optic nerve. This organism was also found in histologic sections from the right adrenal gland, left kidney, thyroid, urinary bladder, right lung, skin, esophagus, sputum, vessels of the myocardium, and brain. To our knowledge, A terreus endophthalmitis has not been reported previously.
Role of nasal allergy in chronic maxillary sinusitis--diagnostic value of nasal challenge with allergen. The role of nasal allergy in chronic maxillary sinusitis without an air-fluid level was studied in 37 patients. Seventy-three nasal provocation tests with various inhalant allergens were performed in 37 patients by means of rhinomanometry, and maxillary sinus radiographs were performed before and repeatedly after the allergen challenge. Forty-one positive nasal responses (NRs) occurred in 29 patients; 13 were immediate only, 18 were late only, and 10 NRs were dual responses. Of these responses, 32 demonstrated radiographic changes, primarily an increase in mucosal edema and/or opacification. These responses were accompanied by increased pressure in the maxillary sinuses, acute headache, and sometimes otalgia. Eight patients did not develop any NRs; however, increased thickening of the mucosal membrane of the maxillary sinuses, accompanied by subjective symptoms, was recorded in three of these nonresponders. These results demonstrate the role of nasal allergy in some patients with chronic maxillary sinusitis, which may affect the diagnostic and therapeutic approaches to this disorder.
Follow-up status of patients with angiographically normal coronary arteries and panic disorder. Cardiology patients with normal coronary angiography demonstrate continuing and substantial social, health, and work disability. We hypothesized that the diagnosis of panic disorder would mark those for whom continuing disability is most likely. We interviewed 72 such patients at the time of their normal angiogram, and then again an average of 38 months later. Those with panic disorder (n = 36) demonstrated significantly more disability at follow-up than did the other study patients. We conclude that those patients with normal angiograms who have panic disorder are more disabled than those who do not have panic disorder. Panic disorder in psychiatric samples has been shown to be highly treatable. Therefore, early identification and treatment of panic disorder in this group is likely to minimize the suffering associated with this condition.
Magnetic resonance imaging of experimental rat brain tumors: histopathological evaluation. Using RG-C6 glioma-transplanted rats, we studied precontrast and postcontrast magnetic resonance imaging, extravasation of Evans blue, and histology. In all rats, tumor was enhanced with gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA). The necrotic portion in the tumor, however, was not enhanced. Hemorrhage and hydrocephalus were clearly visualized on both the precontrast and postcontrast images. Blood-brain barrier-disrupted areas stained with Evans blue and areas enhanced with Gd-DTPA on magnetic resonance imaging were nearly consistent. It is suggested that the mechanism of brain tumor enhancement with Gd-DTPA on magnetic resonance imaging is simply related to the degree of alteration of the blood-brain barrier. The Gd-DTPA-enhanced magnetic resonance imaging, even with low magnetic field, is useful for the evaluation of size, shape, and location of experimental rat brain tumors.
Mild hypothermic intervention after graded ischemic stress in rats. We investigated the effect of mild (34 degrees C) postischemic hypothermia on hippocampal neuronal damage in 43 rats as a function of the duration of forebrain ischemia. Two temperatures and two durations were investigated. In two normothermic groups ischemia lasted 8 (n = 15) and 12 (n = 10) minutes, respectively. In two hypothermic groups ischemia lasted 8 (n = 9) and 12 (n = 9) minutes, respectively, and was followed immediately by the lowering and maintenance of rectal temperature to 34 degrees C for 2 hours. Seven days after the ischemic insult, the rats were sacrificed and the brains were prepared for histologic analysis; the percentage of necrotic neurons among the total neuronal population in selected CA1/2 sectors of the hippocampus was determined. There was a significant decrease in the percentage of necrotic neurons in the central (77.5% versus 55.5%, p = 0.006) and lateral (62.5% versus 38.9%, p=0.005) areas and in the overall CA1/2 sector of the hippocampus (71.8% versus 52.2%, p = 0.008) for the 8-minute hypothermic group compared with the 8-minute normothermic group. In contrast, no differences were detected in any area of the hippocampus between the 12-minute normothermic and the 12-minute hypothermic groups (p = 0.29-0.49). Our data indicate that mild postischemic whole-body hypothermia ameliorates neuronal survival when ischemia lasts 8 minutes but not 12 minutes.
Termination of acute atrial fibrillation in the Wolff-Parkinson-White syndrome by procainamide and propafenone: importance of atrial fibrillatory cycle length. The effects of intravenous procainamide (n = 30) or propafenone (n = 25) were evaluated in 55 patients with acute atrial fibrillation and the Wolff-Parkinson-White syndrome. All patients received either procainamide (12 to 15 mg/kg body weight) or propafenone (1 to 2 mg/kg) during sustained (greater than 10 min) atrial fibrillation or after termination of nonsustained atrial fibrillation. Termination of atrial fibrillation was attributed to a drug if it occurred less than or equal to 15 min after infusion. Measurements included mean cycle length of fibrillatory electrograms (mean AA interval) as measured at the high right atrium and shortest RR interval between pre-excited cycles during atrial fibrillation. Atrial fibrillation terminated more frequently after procainamide administration (65%) than after propafenone (46%), although this difference was not significant. Procainamide prolonged the shortest pre-excited RR interval (228 +/- 41 to 339 +/- 23 ms, p = 0.0001) as did propafenone (215 +/- 40 to 415 +/- 198 ms, p = 0.0001) and the magnitude of increase was greater for propafenone (p = 0.048). Patients with sustained atrial fibrillation had shorter mean AA intervals than did their counterparts with nonsustained atrial fibrillation (123 +/- 25 versus 186 +/- 35 ms, p = 0.0001). Termination of sustained atrial fibrillation by either drug was accompanied by prolongation of the mean AA interval but not necessarily by the shortest pre-excited RR interval. Termination of atrial fibrillation was heralded by a 68% increase in the mean AA interval after procainamide administration compared with a 30% increase when the arrhythmia persisted. For propafenone the increases were 90% and 68%, respectively.
Human cerebral malaria: association with erythrocyte rosetting and lack of anti-rosetting antibodies. Plasmodium falciparum isolates from 24 Gambian children with cerebral malaria and 57 children with mild forms of the disease were assessed for their ability to form erythrocyte rosettes. All isolates from the children with cerebral malaria were able to form rosettes, whereas those from children with mild forms of the disease did not form rosettes, or had a significantly lower rosetting rate. Plasma of children with cerebral malaria lacked anti-rosetting activity, whereas plasma of children with mild disease could often disrupt rosettes in vitro. A monoclonal antibody to P falciparum histidine rich protein (PfHRP1/KP/KAHRP) disrupted rosettes of many of the isolates in vitro indicating that the rosetting ligand is relatively conserved compared with ligands associated with endothelial cytoadherence. The findings strongly support the hypothesis that erythrocyte rosetting contributes to the pathogenesis of cerebral malaria and suggest that anti-rosetting antibodies protect against cerebral disease.
What practicing physicians in North Carolina rate as their most challenging geriatric medicine concerns. We recently surveyed a random sample of 500 physicians in family practice, general practice, and internal medicine in North Carolina, to discover their most challenging geriatric concerns. Using a three-stage survey technique, respondents were asked to answer two open-ended questions about the most challenging geriatric problems they face and what specific geriatric content areas would attract their participation in an educational program. They were then asked to rank 34 topics on which they would like more information. A total of 242 responses were received for a 55% response rate (63 of the 500 were undeliverable). Responses indicated that physicians are more concerned with management than diagnosis and revealed considerable evidence of empathy and concern. The top three topics had to do with the management of dementia, multiple problems, and depression. Approximately 25% of physicians consider problems of financing health care as among the most challenging problems.
Composite reconstruction for chest wall and scalp using multiple ribs-latissimus dorsi osteomyocutaneous flaps as pedicled and free flaps. A composite flap is presented based on the latissimus dorsi myocutaneous unit together with the underlying ninth to eleventh ribs. Three patients are presented. In two, a full-thickness chest-wall defect was present. In one, a full-thickness scalp and cranial defect was present. Use of the composite osteomyocutaneous latissimus dorsi free flap as a pedicled flap in two patients and as a free flap in one patient resulted in successful definitive reconstruction in all with no complications. This procedure necessitates no transplantation of soft tissue prior to bone grafting to maintain local vascularity, so the simultaneous one-stage reconstruction of an osseous-soft-tissue defect becomes possible easily.
Amebic meningoencephalitis in a patient with AIDS caused by a newly recognized opportunistic pathogen. Leptomyxid ameba. A fatal case of meningoencephalitis due to a leptomyxid ameba in a patient with the acquired immunodeficiency syndrome is presented. This opportunistic organism has not been previously recognized as a human pathogen. A 36-year-old male intravenous drug abuser died after an 18-day hospital course heralded by fever and headache and followed by nuchal rigidity and hemiparesis. Computed tomography of the head showed multiple hypodense lesions. Neuropathologic examination showed that in addition to human immunodeficiency virus encephalomyelitis, there was multifocal meningoencephalitis with trophozoites and cysts morphologically indistinguishable from those of Acanthamoeba. These organisms were also found in the kidneys and adrenal glands. By immunofluorescence, the parasites showed antigenic identity with a free-living leptomyxid ameba and failed to react with any of a spectrum of antiacanthamoeba antisera. This emphasizes the importance of immunofluorescence identification of morphologically indistinguishable ameba species.
Cardiotoxicity of interferon. A review of 44 cases. Cardiovascular complications have occurred in clinical trials of interferon. We review herein experience to date of cardiotoxicity with all types of interferons in cancer patients. The most common presentations of cardiotoxicity were cardiac arrhythmia, dilated cardiomyopathy, and symptoms of ischemic heart disease, including myocardial infarction and sudden death. The cardiac effects were not related to the daily dose, cumulative total dose, or period of therapy. Some of the patients in whom interferon has caused cardiovascular sequelae have had a history of coronary heart disease or have previously been given chemotherapy with drugs known to be cardiotoxic. In most of the patients, cardiac toxicity was reversible following the cessation of the drug therapy.
Atrioventricular septal defects. Analysis of short- and medium-term results. Atrioventricular septal defects were repaired in 87 patients from 1981 to 1988. Interventricular communications were present in 73 patients, and major associated anomalies were present in 17 (tetralogy of Fallot in four, double-outlet right ventricle in two, multiple ventricular septal defects in 11). Five deaths occurred in the hospital (5.7%; 70% confidence limits, 3.2% to 9.7%). A preoperative New York Heart Association class V functional condition was the only incremental risk factor (p = 0.02) for death in the hospital. No patient (0%; 70% confidence limits, 0% to 2.15%) had complete heart block. Actuarial survival rate at 80 months was 81.4%. The only incremental risk factor (p = 0.005) leading to reoperation was a preoperative valve incompetence. Actuarial rate at 80 months for freedom from reoperation was 84.2% in the overall group of patients after repair of atrioventricular septal defect. We conclude that an improvement in survival and success rates should be found when a policy of earlier repair is followed.