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Biomedical subjects

J Hart

Publications and source records attributed to J Hart.

At least 199 records · Page 11Linked to original sources
PubMed1990

Free proximal trisomy 21 in the mother and malformation syndrome in the son.

We report on a new case of duplication of the proximal part of the long arm of chromosome 21. The proposita presents normal mental development, no trisomy 21 manifestations; on the contrary, she had a few monosomy 21-like stigmata. She gave birth to a severely malformed infant with a pattern of malformations suggesting a partial 21-monosomy syndrome, but with a 46,XY normal karyotype in his peripheral blood lymphocytes. The findings are explained in the following way: the infant probably had originally a 47,XY,+21q- karyotype like his mother. Post zygotic nondisjunctional events produced a prevalent 46,XY,21q- line responsible for the severe malformations and the normal 46,XY line found in his blood lymphocytes.

Abnormalities, Multiple↗
PubMed1990

Delineation of single-word semantic comprehension deficits in aphasia, with anatomical correlation.

In 3 of 18 aphasic patients pure deficits in semantic comprehension at the single-word level were defined through a series of tasks that excluded possible confounding deficits in auditory perception, visual perception, or speech production. In these pure cases, deficits were found at the superordinate, equivalence, and subordinate levels of single-word semantic processing. Pure semantic deficits were found to be correlated with damage to the left posterior temporal and inferior parietal region; patients whose damage spared this area did not evince such deficits, and the converse was also true. This study confirms the existence of separable deficits in semantic comprehension and points conclusively to the left posterior temporal and inferior parietal region as being critical for semantic processing. This anatomical localization is in keeping with anatomical studies from nonhuman primates, suggesting that these regions may be concerned with multimodal processing and integration of language.

Aphasia↗
PubMed1990

Parameters for direct cortical electrical stimulation in the human: histopathologic confirmation.

Safe parameters for electrical cortical stimulation in humans are difficult to estimate from the animal experimental literature. We therefore examined the light microscopic histology at a total of 11 sites of direct subdural electrical stimulation, taken as part of anterior temporal lobectomies in 3 patients. Stimulations had been done through 3.175 mm diameter electrodes, with 0.3 msec square wave pulses of alternating polarity at 50 pulses/sec. In 2 patients, one site each had been used as a common reference for stimulation, receiving over 251 stimulation trials, most of 2-5 sec duration, at currents of 12.5-15.0 mA, 1 day prior to resection. The maximum charge per phase was 4.0-4.4 microC; the maximum charge density was 52-57 microC per geometric cm2 per pulse at the electrode surfaces. Comparison of hematoxylin and eosin, periodic acid-Schiff, and cresyl violet-stained material from the electrode sites with that from other regions did not show any histologic abnormalities attributable to the electrical stimulation. The relatively brief and intermittent periods utilized for human stimulation testing do not appear to cause structural damage at the light microscopic level at charge densities that exceed the threshold for damage established in animal studies with more continuous, chronic stimulation schedules.

Electric Stimulation↗
PubMed1990

Anti-tumor necrosis factor antibody enhances allograft survival in rats.

We have recently observed significantly elevated serum tumor necrosis factor-alpha (TNF-alpha) levels during human liver allograft rejection. Although increased TNF activity has been reported in rejecting rat cardiac and renal allografts, this represents the first report of an animal model utilizing immunotherapy directed against TNF. Intraabdominal heart transplants (Buffalo to Lewis) were performed. Cardiac rejection was defined as cessation of a palpable beat and confirmed at laparotomy. Control animals received no immunotherapy and experienced rejection on Postoperative Day 11 +/- 0.4 (mean +/- SEM). Experimental animals received immunotherapy either intraperitoneally (ip) or intravenously (iv) from Days 1 to 10. Intraperitoneally administered anti-TNF-alpha prolonged graft survival to 16 +/- 2.7 days (P less than 0.05 vs controls), iv administration prolonged survival to 15 +/- 1.4 days (P less than 0.004). Animals treated with ip anti-TNF-beta survived 17 +/- 1.7 days (P less than 0.002 vs controls). Conversely, administration of purified TNF-alpha to graft recipients decreased graft survival to 7 +/- 0.4 days (P less than 0.001 vs controls). Serum samples analyzed in an L929 bioassay showed increased cytotoxic activity in control animals, corresponding to an increase in circulating TNF. This activity was partially abrogated in animals receiving immunotherapy. These data demonstrate that circulating levels of TNF are increased during rejection. Immunotherapy with anti-TNF-alpha or anti-TNF-beta prolongs graft survival, suggesting that TNF may play a role in the pathogenesis of acute allograft rejection.

Animals↗
PubMed1990

The role of tumor necrosis factor in allograft rejection. II. Evidence that antibody therapy against tumor necrosis factor-alpha and lymphotoxin enhances cardiac allograft survival in rats.

In the previous study we demonstrated that circulating levels of TNF-alpha are elevated during liver allograft rejection and may precede clinical manifestations. The current study was designed to investigate the efficacy of antibody therapy against tumor necrosis factor-alpha and lymphotoxin (LT) in a rat heterotropic cardiac transplant model utilizing Buffalo donors and Lewis recipients. Control animals received no immunotherapy and experienced rejection on postoperative day 11 +/- 0.4 (mean +/- SEM). Experimental animals received immunotherapy either intraperitoneal or intravenous from days 1 to 10. The i.p. administered anti-TNF-alpha prolonged graft survival to 16 +/- 2.7 days (P less than 0.05 vs. controls); the i.v. administration prolonged survival to 15 +/- 1.4 days (P less than 0.004). Animals treated with i.p. anti-LT survived 17 +/- 1.7 days (P less than 0.002 vs. controls). Combination immunotherapy of anti-TNF-alpha and anti-LT increased function to 21 +/- 2.2 days (P less than 0.001 vs controls). Conversely, administration of purified TNF-alpha or LT to graft recipients accelerated the time to rejection. Mean survival for both treatments was 7 days (P less than 0.001 vs. controls). Histologic examination of the transplanted cardiac tissue showed a typical pattern for acute rejection; there was no evidence of hemorrhagic or coagulative necrosis. In contrast, administration of purified TNF-alpha or LT to recipients of a syngeneic heart did not stimulate rejection. These data suggest that TNF-alpha and LT may play a role in the pathogenesis of acute allograft rejection. In addition, the mechanism appears to be distinct from that seen in TNF-alpha or LT-mediated cytotoxicity of tumor cells.

Animals↗
PubMed1990

Inverse relationship between total glutathione S-transferase content and bile acid release in isolated hepatocytes from untreated, phenobarbital pretreated and hypothyroid rats.

The role of cytosolic anion binding proteins (glutathione S-transferases) in the hepatic transport of bile acids remains controversial. To investigate whether increased levels of the hepatocyte total glutathione S-transferase content were associated with changes in the release of bile acids from the hepatocyte, we measured the rate of release of radioactive bile acids in isolated hepatocytes from thyroidectomized, phenobarbital pretreated and untreated rats. The isolated hepatocytes were preincubated with either 14C-cholic acid or 14C-taurocholic acid, and the release rate of radiolabeled bile acids was determined. Hepatocyte total glutathione S-transferase content was measured by rocket immunoelectrophoresis. The release rate of the radiolabeled bile acids was significantly (P less than 0.005) decreased in both hypothyroid and phenobarbital pretreated hepatocytes. The levels of total glutathione S-transferase content were significantly (P less than 0.001) increased in the hepatocytes from both hypothyroid and phenobarbital pretreated animals. Our findings reveal a striking inverse relationship between the total glutathione S-transferase content of the hepatocyte and the release rate of radiolabeled bile acids in isolated hepatocytes from two independent animal models. These observations support the hypothesis that cytosolic anion binding proteins (glutathione S-transferases) may influence the net flux across the hepatocyte plasma membrane largely by limiting efflux.

Animals↗
PubMed1990

Early-onset dementia and extrapyramidal disease: clinicopathological variant of Gerstmann-Straussler-Scheinker or Alzheimer's disease?

A case of progressive dementia and extrapyramidal signs beginning at age 29, with a ten year course until death, is presented. Necropsy examination showed an assortment of plaque types (including striatal plaques), neurofibrillary tangles, granulovacuolar degeneration, and depigmentation of the substantia nigra and locus ceruleus. This case had pathological features found in both Gerstmann-Straussler-Scheinker disease and in Alzheimer's disease. While somewhat similar to several other cases with features of both diseases, it differs in the presence of dystonia and striatal plaques. Although such cases may be difficult to categorize at present, they must be considered in the differential diagnosis of early onset dementia.

Adult↗
PubMed1990

Resection of the epileptogenic area in critical cortex with the aid of a subdural electrode grid.

Electrode grids were implanted subdurally in 28 patients with epilepsy. In 16 of the 28 patients, an epileptogenic area was located in the speech-dominant left temporal lobe. Recordings made with the grid revealed that the epileptogenic areas in the patients varied widely in extent: the area was confined within the first 10 mm of the temporal lobe in some patients or it was scattered throughout the entire anterior to posterior 80-mm extend in others. Resection of the epileptogenic area was adjusted accordingly in each case. In 6 of 16 patients who were left-hemisphere-dominant for language, up to 55-80 mm from the tip of the temporal lobe was removed, a measure that exceeds the conventional limit of 50 mm from the tip of the dominant hemisphere. In the remaining 12 of the 28 patients, epileptogenic areas were located in a combination of several lobes. In 7 of these 12 patients, the epileptogenic area encompassed the rolandic area; it was removed without deficit in 4 patients and with expected deficit in 3. Of the latter 3 patients, 1 patient underwent hemispherectomy, and a large portion of the epileptogenic rolandic cortex in the frontal and parietal lobes was removed from the other 2. There were 2 cases of grid-related infection, which cleared with antibiotic treatment; there were no lasting complications of grid implantation in any patient. There was no mortality. Electroencephalographic recording and functional mapping using subdural electrode grids allow a tailored, maximal resection of epileptogenic tissue with minimal injury to critical cortex.

Brain Diseases↗
PubMed1990

Dextromethorphan for treatment of complex partial seizures.

We performed a double-blind, crossover, add-on study of the antitussive agent dextromethorphan (DM 120 mg/d) as therapy for seizures on 9 patients suffering from severe complex partial seizures. DM had no significant influence on key laboratory values, nor on anticonvulsant drug levels. Side effects were negligible. Complex partial seizure frequency increased 25% during the DM arm of the study, although this increase was not clinically significant.

Adult↗
PubMed1990

Characterization of the basal temporal language area in patients with left temporal lobe epilepsy.

We evaluated 5 consecutive patients with subdural grid electrodes (including placement over the left basal temporal region) for focal resections for control of intractable epilepsy. All 5 had language dysfunction when we performed cortical stimulation over the basal temporal region (the inferior temporal gyrus, the parahippocampal gyrus) using a systematic battery of language tests. The area in which language interference could be produced began from at least 11 to 35 mm posterior to the temporal tip and ended at least 39 to 74 mm posterior to the temporal tip. The most consistently impaired language tasks were spontaneous speech and passage reading, but there was impairment of all language functions tested in some patients. Language deficits after dominant temporal lobectomy may result from resection of this area.

Adult↗
PubMed1990

Disease recurrence following liver transplantation.

Recurrence of disease following liver transplantation is emerging as a major area of concern. We retrospectively investigated for evidence of recurrent hepatitis B, hepatitis non-A, non-B (NANB), primary biliary cirrhosis (PBC) and malignancy in 106 transplant patients. Recurrence of hepatitis B was diagnosed in 11 of 14 (79%) patients who survived longer than 2 months posttransplant. The first histologic evidence of recurrence occurred at 4 to 64 weeks posttransplant (mean, 22.2 weeks). In two patients, progression to cirrhosis was documented histologically. Recurrence was diagnosed in three patients transplanted for fulminant hepatic necrosis due to hepatitis B. Administration of hepatitis B vaccine and hepatitis B immunoglobulin was ineffective in preventing recurrence. Recurrence of hepatitis NANB was diagnosed in only two of 23 patients transplanted for hepatitis NANB cirrhosis. Evidence of posttransplant hepatitis was also detected in one of 10 patients transplanted for fulminant hepatitic failure presumably caused by hepatitis NANB. Recurrence of PBC was not diagnosed in any of 15 patients, but the length of follow-up was too limited in most patients to allow definite conclusions to be made. Posttransplant antimitochondrial antibodies titers remained elevated in nine of 11 patients tested. Six of 13 patients transplanted for hepatocellular carcinoma (46%) developed recurrent tumor, and five died. The role of preoperative and postoperative chemotherapy is currently undefined.

Adolescent↗
PubMed1990

Frequency of clinical gallstone disease among Yemenite Jews in Israel.

The prevalence of gallstones in Yemenites in Israel was reported in an early hospital-based study to be very low. The current prevalence of clinical gallstone disease in this population group was estimated and compared with that in a predominantly European (Ashkenazi) community by a review of 1,000 family practice medical charts in each community. The crude rate in the Yemenite community was 3.1% for those over the age of 20, and the age-adjusted relative risks were 1.1 for men and 3.1 for women, compared with the control population. The regional hospital cholecystectomy rates for the Yemenite community were slightly lower than for the general population, but the Yemenites were more likely to have emergency than elective surgery. The rate of positive findings and complications revealed by clinical ultrasound examinations was also higher among Yemenites than in the general population. This study corrects the mistaken impression that gallstones are a rare phenomenon among Yemenites.

Adult↗
PubMed1989

Relation between DNA ploidy and the clinical behavior of phyllodes tumors.

We studied the DNA histograms obtained by flow cytometry from a series of six giant fibroadenomas and ten phyllodes tumors to determine if the analysis of DNA ploidy would help to predict clinical behavior. We were unable to document any relation between ploidy and histologic appearance, recurrence, metastasis, lesion size, or patient age. DNA aneuploid stem cell lines were seen in 75% of histologically benign phyllodes tumors, 50% of histologically malignant phyllodes tumors, and approximately 33% of giant fibroadenomas.

Adenoma↗
PubMed1989

Amanita poisoning: treatment and the role of liver transplantation.

Fatal mushroom poisoning has long been recognized as a major health problem in western Europe and more recently in the United States. The majority of deaths are attributable to the genus Amanita. Amanita phalloides (death cap) has been found with increasing frequency across the United States and presents a significant health hazard in this country to those who pick and consume wild mushrooms. This article discusses the pharmacologic basis and clinical manifestations of Amanita intoxication. It outlines the rationale of various treatment modalities and, from these, summarizes a protocol that the authors believe will be useful to the clinician. In addition, two patients are presented who underwent successful orthotopic liver transplantation for fulminant hepatic failure secondary to Amanita poisoning. The role of liver transplantation both acutely and as treatment for chronic active hepatitis secondary to severe intoxication is discussed.

Adult↗
PubMed1989

The significance of membrane changes in the safe and effective use of therapeutic and diagnostic ultrasound.

The cellular changes, such as alterations in motility and the stimulation of synthesis and secretion, induced by relatively low intensities of therapeutic ultrasound (e.g. 500 mW cm-2, SAPA; 100 mW cm-2 SATA) are primarily non-thermal in origin. They appear to be associated with changes in the permeability of the cell (plasma) membrane and in the transport of ions and molecules across it, effects which have been demonstrated in cells irradiated in suspension. In epithelial tissues, both in vitro and in vivo, it has been demonstrated that not only the cellular membrane transport pathways but also the paracellular or intercellular pathways are affected. Although membrane-mediated effects can be of value therapeutically, they could produce adverse effects if they were to occur during development, for the reception and transmission by the membrane of environmental signals are involved in determination of the fate of each cell. Determination is followed by selective gene expression and differentiation, that is, by the progressive increase in structural complexity brought about by the acquisition of specialised characteristics by various cell groups. Most cells of early embryos are ionically coupled via gap junctions which provide an intercellular pathway for electrochemical signalling and the maintenance of the concentration gradients which provide the cells with positional information. Differentiation of the cells varies according to their location with respect to these gradients. Increase in the intracellular concentration of calcium ions, which has been shown to occur after exposure to therapeutic levels of ultrasound, can decrease the permeability of gap junctions and uncouple cells, in the manner which occurs when they differentiate. Ultrasonically induced increases in calcium ion concentration are thus of considerable clinical significance, since they could affect differentiation and consequently histogenesis. Modification of plasma membrane permeability and transport properties, resulting in changes in the availability and activity of second messengers such as free calcium ions, can have profound effects on cell behaviour. Calcium channels appear to be the first channels to develop in the cell membranes of embryos, and internal calcium ion concentration is known to affect the synthesis of fetal proteins. Although generally reversible at intensities of less than 500 mW cm-2, changes in membrane permeability, particularly to calcium ions, could, if prolonged, have undesirable side effects not only on embryogenesis but on late prenatal and postnatal development. It is therefore recommended that the environmental conditions, thresholds, and mechanisms involved in the production of such changes be determined, so that they can be avoided when ultrasound is used diagnostically on sensitive targets such as embryos and fetuses.

Animals↗
PubMed1989

Lymphokine production in patients with Alzheimer's disease.

The capacity of peripheral blood mononuclear cells (PBMC) isolated from patients with Alzheimer's disease to produce interleukin-1 and -2 (IL-1, IL-2) was compared to that of cells from age-matched controls and young healthy subjects. There was no difference in the production of both interleukins between patients and their age-matched controls. On the other hand, the production of IL-1 by the PBMC of healthy young volunteers was significantly higher than that of the cells from patients and subjects of the other two groups. Although the results indicated a higher production of IL-2 by PBMC from younger individuals, the difference in comparison with the other two groups was not statistically significant.

Adult↗