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Biomedical subjects

J Hart

Publications and source records attributed to J Hart.

At least 127 records · Page 7Linked to original sources
PubMed1996

Effect of high doses of 2-CdA on Schwann cells of mouse peripheral nerve.

The present study was undertaken to examine the effect of 2-CdA (Leustatin) on the Schwann cells of myelinated and unmyelinated fibers of peripheral mouse nerve. Two groups of mice were injected intravenously for seven days with 2-CdA: one group received daily doses of 1 mg/kg and the other 0.5 mg/kg. Both doses exceeded those accepted in clinical practice. Mice injected with saline served as controls. The sciatic nerve was then dissected and examined with a transmission electron microscope. The Schwann cells of both the myelinated and unmyelinated nerve fibers of the animals receiving the higher doses of 2-CdA showed nuclear and nucleolus damage, loss of heterochromatin, vacuolization and disorganization of the myelin sheaths. The mesaxons and the axons were also damaged. The Schwann cells of the animals treated with the lower doses appeared undamaged. The results indicate that in contrast to other anticancer drugs known to produce peripheral neuropathy, 2-CdA may cause damage to the Schwann cells only at doses exceeding the therapeutic ones.

Animals↗
PubMed1996

Birth trauma. A five-year review of incidence and associated perinatal factors.

OBJECTIVE: To determine the current incidence of clavicular fracture (CF), facial nerve injury (FNI) and brachial plexus injury (BPI) and identify the existence, if any, of associated perinatal factors with each injury. STUDY DESIGN: A case-controlled study design was selected and the study conducted for births between January 1, 1985 and January 1, 1990, at Christ Hospital and Medical Center, a tertiary care center with level III perinatal services in suburban Chicago. Among a population of 19,370 consecutive deliveries, we identified the occurrences of CP, FNI and BPI by database search, and maternal and neonatal chart reviews. A control group was randomly selected. Maternal, labor, delivery and neonatal variables were then compared between the birth trauma and control groups for each specific injury. RESULTS: The incidence per 1,000 live births and per 1,000 live-born cephalic singletons delivered vaginally for CF was 4.5 and 5.7; for FNI, 0.6 and 0.7; and for BPI, 0.9 and 1.1, respectively. To varying degrees, the data demonstrate that the occurrences of these injuries are associated significantly more often with prolonged gestation, epidural anesthesia, prolonged second stage of labor, oxytocin use, forceps delivery, shoulder dystocia, macrosomia, low Apgar scores and a previous maternal obstetric history of macrosomia when compared to controls. Other significantly associated variables include the presence of meconium in labor and neonatal hyperbilirubinemia. Despite the presence of multiple perinatal factors that are individually associated statistically with the injured groups, multiple logistic regression analysis predicted 44.2% of CF's, none of the FNIs and only 19% of the BPIs. CONCLUSION: While multiple perinatal variables are statistically associated with the specific birth injuries studied, the use of multiple logistic regression analysis shows that the ability to predict these injuries is markedly limited.

Birth Injuries↗
PubMed1996

Plasma fibrinogen in Israeli Moslem and Jewish school-children: distribution and relation to other cardiovascular risk factors. The Petah Tikva project.

Plasma fibrinogen levels were measured in 1,175 Israeli schoolchildren, aged 9-18 years, originating from diverse ethnic groups. The Moslem children displayed striking differences in levels and age-patterns of fibrinogen compared to Jewish children. Lower mean plasma fibrinogen levels in boys aged 9-10, 13-14 and 16-18 were observed among Moslem boys, compared to their Jewish counterparts born in Israel. Moslem girls showed lower levels of fibrinogen than Jewish Israeli girls at ages 9-10 and 16-18. While the Jewish children displayed an age-associated fibrinogen pattern comparable at the three age groups, the levels for Moslem children increased pre-puberty and decreased post-puberty, peaking at 13-14 years. No significant difference in mean plasma fibrinogen was found between sexes within ethnic groups. A number of statistically significant but low correlations (-0.32 to 0.24) were found between plasma fibrinogen and high density lipoprotein cholesterol (HDL-C) as a percentage of total cholesterol, triglycerides, blood glucose, uric acid, blood pressure, Quetelet index and sports activity. The difference between fibrinogen levels might point to a possible ethnicity risk factor explanation rather than environmentally acquired factors.

Adolescent↗
PubMed1996

Patient satisfaction in two departments of surgery in a community hospital.

Patient satisfaction with medical and nursing care was evaluated in two surgical departments of a community teaching hospital in Petah Tikva (now called Rabin Medical Center, Golda Campus). The interview, conducted before the patients were discharged, related to their perception of the preoperative period, the attitude of the personnel in the operating room before anesthesia was administered, and their satisfaction during the postoperative period. The questionnaire completed by the interviewer included questions on the time that elapsed from admission to the first examination by a physician and a nurse, whether the patient received information about the operation and its possible complications, was examined by the anesthetists, received details regarding the results of the surgical procedure, and what his or her impression was of the attitude of the nursing staff. The patients were asked to rate their evaluation on a scale from 1 to 10. The results showed high satisfaction with the services provided and were similar for both departments. The small number of patients whose satisfaction rated from 5 to 8 complained about the sanitary conditions in the toilets, the overcrowded departments, and the lack of sufficient number of registered nurses during the night shifts.

Adolescent↗
PubMed1996

Quaternion contact ribbons: a new tool for visualizing intra- and intermolecular interactions in proteins.

Protein side chain interactions between residues separated by at least one loop or turn or break in the amino acid sequence are called 'nonlocal contacts' in this manuscript, and contiguous sets of such interactions located between segments of secondary structure are called 'contact zones.' A new interactive program, the quaternion contact ribbon tool, has been developed to help protein chemists identify, straighten if twisted, and display contact zones between two neighboring segments of helix.

Binding Sites↗
PubMed1995

The epidemic of gang-related homicides in Los Angeles County from 1979 through 1994.

OBJECTIVE: To determine trends in gang homicides and the population at greatest risk for homicide by reviewing all gang-related homicides in Los Angeles County, California, from January 1979 to December 1994. DESIGN: Homicide files of the Los Angeles Police Department and the Los Angeles County Sheriff's Department from 1979 to 1994 involving violent street gang activity were reviewed. Gang files were reviewed for demographic data, weapons used, homicides by drive-by shootings, and times and geographic areas of occurrence. SETTING: Los Angeles County from January 1, 1979, to December 31, 1994. MAIN OUTCOME MEASURES: Age, race, and sex of gang-related homicide victims; frequency of weapon use; and the change in gang-related homicide rates during the study period. RESULTS: A total of 7288 gang-related homicides occurred in Los Angeles County from 1979 through 1994; 5541 of these homicides occurred in Los Angeles Police Department and Los Angeles County Sheriff's Department jurisdictions. During the study period, the proportion of all homicides that were gang related increased from 18.1% to 43.0% (P < .001). Of the 5541 gang-related homicide victims, 4580 (85.6%) were aged 15 to 34 years, 93.3% were African American or Hispanic, 5157 (93.2%) were male, 3559 (64.2%) were gang members, and 1408 (25.4%) occurred during drive-by shootings. Firearms were used in an increasing proportion of homicides, from 71.4% in 1979 to 94.5% in 1994. Homicides by semiautomatic handguns dramatically increased during the study period. Gang-related homicide rates for African-American males aged 15 to 19 years increased from 60.50 per 100,000 population per year in 1979 to 1981 to 192.41 per 100,000 population per year in 1989 to 1991. CONCLUSIONS: Gang-related homicides in Los Angeles County have reached epidemic proportions and are a major public health problem. To prevent gang violence, the root causes of violent street gang formation must be alleviated, the cycle of violent street gang involvement must be broken, and access to firearms must be limited.

Adolescent↗
PubMed1995

1 alpha,25-Dihydroxy-16-ene-23-yne-26,27-hexafluorocholecalciferol, a noncalcemic analogue of 1 alpha,25-dihydroxyvitamin D3, inhibits azoxymethane-induced colonic tumorigenesis.

Vitamin D3 and its metabolites, particularly 1 alpha,25-dihydroxyvitamin D3 (1 alpha, 25(OH)2D3), have received increasing attention as potential anticarcinogens in the prevention of cancers in a number of organs, including the colon. These agents, however, have the potential to induce hypercalcemia, thus limiting their practical use for these purposes. In the present studies it was, therefore, of interest to determine whether dietary supplementation with 1 alpha,25-dihydroxy-16-ene-23-yne-26,27-hexafluorocholecalcifero l (RO24-5531), a recently synthesized apparently noncalcemic analogue of 1 alpha,25(OH)2D3, inhibited colon cancer induced by azoxymethane (AOM). Rats were placed on a standard diet or fed this diet with supplemental RO24-5531 (2.5 nmol/kg feed) before and during (initiation arm), or after AOM or vehicle administration (postinitiation arm). After 34 weeks of study, animals in each group were sacrificed, and their colons were removed and examined macroscopically and microscopically for the presence of tumors. At the time of sacrifice, the animals' serum calcium, phosphorus, 25-hydroxyvitamin D3 and 1 alpha,25(OH)2D3 levels were also analyzed. The results of these studies demonstrated that dietary RO24-5531 supplementation during the initiation arm of these experiments significantly reduced (by 70%) the incidence of AOM-induced colonic tumors compared to rats on the standard diet without RO24-5531. Moreover, this dietary regimen abolished the development of adenocarcinomas in this model. Although there was also a trend for dietary RO24-5531 supplementation during the postinitiation arm of this study to reduce the incidence of colon tumors, this did not reach statistical significance (P > 0.05). In addition, neither dietary RO24-5531 supplementation regimen significantly influenced the animals' rates of growth or their serum levels of calcium, phosphorus, or 25-hydroxyvitamin D3. These studies, therefore, demonstrate for the first time that supplemental dietary RO24-5531 is a chemopreventive agent in the AOM model of experimental colonic carcinogenesis. They also suggest that this agent may ultimately prove useful in clinical colon cancer chemopreventive trials.

Animals↗
PubMed1995

Remodelling of lipoproteins in transgenic mice expressing human cholesteryl ester transfer protein.

Cholesteryl ester transfer protein (CETP) facilitates the transfer of reciprocal exchange of neutral lipids between lipoproteins. To better understand the function of CETP and its role in atherogenic pathways, transgenic mice which express human CETP were generated. The transgene encoding human CETP was under the control of the mouse alpha-fetoprotein enhancer and mouse albumin gene promoter and was expressed exclusively in the liver. The level of human CETP activity in transgenic mouse plasmas was found to be 1- to 5-fold greater than in normolipidemic human plasma. Human CETP induced an approx. 30 and 40% reduction of HDL cholesterol levels in plasma from female and male transgenic mice, respectively, when compared to controls. In addition, multiple alterations in mouse lipoprotein composition were observed in the transgenic mice. Diminished HDL cholesterol levels and disappearance of the apo E-rich HDL1 moiety account for the dramatic reduction in plasma cholesterol. The decrease in HDL cholesterol was accompanied by a marked reduction in HDL particle size and apo A-I content. The cholesterol content and the size of LDL particles increased, but only modestly, in transgenic mouse plasma. In conclusion, human CETP induces a significant remodelling of mouse lipoproteins which results in dramatic reduction in plasma cholesterol levels.

Animals↗
PubMed1995

Chaparral ingestion. The broadening spectrum of liver injury caused by herbal medications.

Unconventional medical practices, including the use of herbal remedies, are prevalent in the United States. Chaparral is an herbal preparation made from a desert shrub and used for its antioxidant properties. We report the case of a 60-year-old woman who took chaparral for 10 months and developed severe hepatitis for which no other cause could be found. Despite aggressive supportive therapy, the patient deteriorated and required orthotopic liver transplantation. She is now well, more than 1 year after her transplant. This case suggests that chaparral can cause serious liver injury and fulminant hepatic failure. Herbal medications should be considered as potential causes of liver toxicity.

Chemical and Drug Induced Liver Injury↗
PubMed1995

Resolution of Helicobacter pylori-associated gastric lymphoproliferative disease in a child.

A possible causative association between Helicobacter pylori infection and gastric lymphoproliferative disorders has recently been recognized. The case of a 14-year-old girl who was diagnosed with H. pylori gastritis and associated gastric lymphoproliferative disease of the low-grade mucosa-associated lymphoid tissue type is reported. The patient was treated only for the H. pylori infection (amoxicillin, bismuth, and metronidazole) without any adjuvant chemotherapy or surgery for her lymphoproliferative disorder. This treatment not only resulted in the eradication of the microorganism but also complete resolution of her lymphoproliferative disease. The patient was subsequently followed up for a period of 7 years. There has been no histological recurrence of H. pylori gastritis or gastric lymphoproliferative disease. It is believed that this is the first report to describe a long-term follow-up of an H. pylori-associated gastric lymphoproliferative disorder in a pediatric patient who was exclusively treated for H. pylori infection. The observations in this report suggest that H. pylori-associated low-grade gastric lymphoproliferative disease can be completely cured by eradicating the organism. Therefore, this therapeutic approach, combined with close follow-up, should be the treatment of choice in children with this associated condition before attempting more aggressive treatments, thus potentially avoiding chemotherapy and/or (partial) gastrectomy.

Adolescent↗
PubMed1995

Contribution of class I HLA-A2 antigen in immune reactions.

The involvement of the Class I HLA-A2 antigen is briefly reviewed in relation to allograft rejection, the feto-maternal relationship, viral cytotoxic reactions and tumor immunity. It is suggested that the HLA-A2 molecule may have, as compared to other HLA Class I alleles, a dominant role as a restricting element in cytotoxic T-cell recognition in the feto-maternal relationship to male fetuses, in specific viral infections and in tumors. As compared to other HLA Class I alleles, its reduced expression or loss in a variety of tumors suggests its possible important role in tumor immune surveillance. The disappearance of HLA-A2 from tumor cells may eventually contribute to the escape from T-cell recognition of malignant cells.

Cytotoxicity, Immunologic↗
PubMed1995

Fulminant hepatitis associated with centrilobular hepatic necrosis in young children.

OBJECTIVE: To describe fulminant hepatic failure (FHF) in children in the United States with clinical and histopathologic features distinctly different from those typical of FHF. PATIENTS: Seven young children were seen in early 1994 with encephalopathy, coagulopathy, and elevated aminotransferase levels. Liver failure was preceded by a prodromal viral illness that resulted in a period of fasting without dehydration. Unlike the majority of children with FHF, these patients had serum bilirubin levels < 171 mumol/L (10 mg/dl). All children had received therapeutic doses of acetaminophen during the prodromal illness. HISTOPATHOLOGIC FINDINGS: Histologic findings included zonal necrosis of hepatocytes in a centrilobular distribution, which is characteristic of toxic liver injury but is atypical for viral hepatitis and sporadic non-A non-B hepatitis. OUTCOME: Six patients recovered spontaneously, and one died of complications of liver failure and fungal sepsis. The cause of this disorder remains unknown, but we postulate a viral or environmental insult that preferentially damages zone 3 hepatocytes. The potential for this injury may have been augmented by ingestion of therapeutic doses of acetaminophen while patients were in a fasted state. The prognosis was good compared with typical FHF in children and correlated with the degree of liver necrosis on histologic examination.

Acetaminophen↗
PubMed1995

Distributed representations of semantic knowledge in the brain.

Category-specific language impairments have been postulated to require the existence of an explicit category organization within semantic memory. However, it may be possible to demonstrate analytically that this is not necessary. We hypothesize that category-specific organization can emerge from perceptual, functional, and associative feature information about objects that is maintained in order to process language. In this paper, we conduct several experiments to test the computational validity of this hypothesis. Physical objects were encoded in terms of semantic features, based on basic perceptual and motor modalities and higher level knowledge of function, for use in artificial neural networks. Mathematical methods were used to analyse the encodings and the neural networks. The results demonstrate the emergence of semantic categories in the networks, although such information was not preprogrammed. We conclude that category-specific language organization can emerge from the inherent nature of semantic features themselves, and does not require special internal categorical organization of semantic memory.

Brain↗
PubMed1995

Phagocytosis-promoting factor in human colostrum.

The effect of colostrum of mothers of preterm and full-term newborns on the phagocytic activity for latex particles by normal peripheral blood polymorphonuclear cells was examined. The results showed that human colostrum contains a phagocytosis-promoting factor(s), which not only increases the number of phagocytic cells, but also stimulates the phagocytic activity of the individual cell. This factor(s) was more active in preterm colostrum. Thus, while term colostrum increased the number of phagocytic cells by 95% in comparison with the control, preterm colostrum enhanced the number of phagocytic cells by 300%. Similarly, term colostrum increased the phagocytic capacity of the individual cell by 51%, whereas preterm colostrum by 137%. The difference between the results in all experimental points was statistically highly significant.

Blood Proteins↗
PubMed1995

Inhibition of leukemic cell proliferation by one or more factors released from splenic BCL1 cells.

Irradiated peripheral blood lymphocytes from patients with chronic B-lymphocytic leukemia (B-CLL) have been shown to secrete a factor or factors that caused inhibition of malignant cell proliferation. In the present study, we used the murine B cell leukemia (BCL1) model system to examine the possible secretion of inhibitory factors from irradiated leukemic spleen cells. It was found that under culture conditions, irradiated spleen cells obtained from leukemic mice produce factors capable of suppressing BCL1 cell proliferation in vitro. The release of an inhibitory factor from nonirradiated cells was also observed, albeit to a lower extent. Supernatants collected from cultured nonirradiated and irradiated cells derived from animals at the first week after BCL1 cell inoculation did not affect the proliferation capacity of cells at any stage of the disease, whereas supernatants obtained at more advanced stages exhibited an inhibitory effect on the proliferation of cells derived from the same stages. The suppressive effect of supernatants of irradiated cells was more pronounced when those of 7 days' culture were used, compared to those of nonirradiated cells. The difference in suppression observed between supernatants of irradiated and nonirradiated BCL1 cells may be attributed either to the same factor produced in a larger amount following irradiation or to two (or more) factors--one produced spontaneously, the other induced by irradiation.

Animals↗
PubMed1995

A case of diclofenac-induced colitis with focal granulomatous change.

We report a case of severe colitis from diclofenac (Voltaren), one of a number of nonsteroidal anti-inflammatory drugs (NSAIDs) that can cause colonic injury. The patient, a 68-yr-old woman, presented with acute onset of bloody diarrhea, having taken diclofenac for more than 2 yr. Colonoscopy revealed deep ulcerations in the transverse colon and erythema and erosions scattered elsewhere. Biopsy findings included crypt distortion, cryptitis, hemorrhage, and some fibrosis. Also, in one biopsy taken from an area of deepest ulceration, a large, non-foreign body-type granuloma was seen, raising the specter of Crohn's colitis. All symptoms subsided within 24 h after discontinuation of the diclofenac, and follow-up colonoscopy 17 days later showed complete endoscopic and histological resolution. Patients and physicians should be aware of the possibility of colitis from NSAIDs. In rare cases, some will show granulomatous change that may be confused with Crohn's disease. Early recognition and discontinuation of NSAIDs is crucial to prevent clinical worsening that could lead to colectomy or even prove fatal.

Aged↗
PubMed1995

Is it possible to improve the autopsy rate?

To improve the autopsy rate in a department of internal medicine, the method reported by Clayton and Sivak in 1992 was simplified and applied for a 12 month period, from January through December 1993. The basic principle of this method is involvement of the senior resident staff and supervision of the project by the head and deputy head of the department, on a daily basis. A simple form was designed for this purpose and was completed for each case. Results were compared with those between the same months in 1992. An increase in the autopsy rate from 1.8% in 1992 to 26.7% during the trial period in 1993 was noted.

Autopsy↗