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Biomedical subjects

M S Jacobson

Publications and source records attributed to M S Jacobson.

67 records · Page 4Linked to original sources
PubMed1982

Hepatic effects of a phthalate ester plasticizer leached from poly(vinyl chloride) blood bags following transfusion.

The effects of di(2-ethylhexyl) phthalate (DEHP) on hepatic function and histology were evaluated in the rhesus monkey undergoing platelet and plasma transfusion. The average cumulative amount infused in one year is comparable to that received by patients who undergo chronic transfusion. Abnormalities in hepatic scan and BSP kinetics persisted for up to 26 months after transfusion, as did histologic abnormalities. Patients undergoing maintenance hemodialysis receive a yearly dose of DEHP which is 10-20 times that which produced hepatotoxicity in the transfused rhesus.

Animals↗
PubMed1982

Screening for pharyngeal gonorrhea in the urban teenager.

A retrospective chart review assessed the occurrence of pharyngeal gonorrhea among 546 teenagers who attended a general adolescent clinic and were cultured for gonorrhea; they had been routinely cultured at three sites (cervix/urethra, rectum, and pharynx) regardless of their history of sexual practice. No record of specific sexual practice was available. This population was predominantly urban, black, and female; the age range was 11 to 22 years (mean = 16.5). The overall occurrence of gonorrhea was 14.7% (80/546). Pharyngeal gonorrhea was detected in 2.7% of the study population, representing 12 females and three males. Of the 80 patients with gonorrhea, 15% had only pharyngeal gonorrhea. History was available for 13/15 patients none had pharyngeal symptoms. Approximately half were detected by routine screening at a family planning visit; the remainder had complaints related to sexually transmitted disease. The occurrence of pharyngeal gonorrhea is sufficiently high to merit study of the indications for pharyngeal culture of teenaged patients. Given the potential for disseminated infection and absence of information regarding the reliability of self-report, it currently appears appropriate to culture adolescents routinely for pharyngeal gonorrhea, regardless of stated sexual practice, whenever genital cultures are collected.

Adolescent↗
PubMed1980

Nutrition and the adolescent: an update.

This article reviews selected nutrition research pertinent to adolescent health care. Protein--calorie malnutrition affects 25% of hospitalized adolescents studied, which correlates, as in adults, with increased morbidity and mortality. Some subgroups of adolescents, notably Asian immigrants, have been shown to be at high risk for developing vitamin D deficient rickets. On the other hand, excessive vitamin D intake has been linked to arteriosclerosis in animal models. Calcium supplementation is not likely to be indicated in U.S. adolescents. Iron deficiency prevalence in adolescence is not well documented, owing to the confusion between anemia and iron deficiency. Serum ferritin and free erythrocyte protoporphyrin measures should help to clarify this issue. Zinc nutrition must be assessed in high-risk groups such as those with short stature or Crohn's disease. Oral contraception effects on vitamin B6 and on serum lipids need to be considered in the risk-benefit equation when prescribing this method of birth control for adolescents.

Adolescent↗
PubMed1980

The influence of dietary cholesterol and fat on the homeostasis of cholesterol metabolism in early life in the rat.

Evidence has accumulated suggesting that exposure to dietary cholesterol during early developmental stages activates biochemical mechanisms that regulte cholesterol homeostasis in adult life. Pregnant Sprague-Dawley rats were fed control or 1% cholesterol [high cholesterol-high fat (HC-HF)] liquid diet during gestation, and with the same diet, offsprings were challenged at maturity. 3-Hydroxy-3-methylglutaryl-coenzyme A reductase activity declined by 76%, and cholesterol 7 alpha-hydroxylase activity increased by 200%. Microsomal and serum cholesterol accumulation also increased significantly. Exposure to HC-HF diet during suckling and continued exposure with the same diet postweaning resulted in 52% decline in 3-hydroxy-3-methylglutaryl coenzyme A reductase and 280% increase in 7 alpha-hydroxylase activity. Serum cholesterol level is not affected although microsomal cholesterol accumulation and the ratio of hepatic to serum cholesterol increased significantly in the experimental group when compared to the nonchallenged group. Rats exposed to HC-HF diet during lactation alone or during gestation and lactation and then challenged demonstrated enzymatic changes of similar magnitude. Serum and microsomal cholesterol levels also increased significantly by 126 and 150%, respectively. The activity of the HMG-CoA reductase system appears to be more sensitive to modulation by diet during gestation than during lactation. However, 7 alpha-hydroxylase activity is susceptible to dietary manipulation with HC-HF diet only during lactation.

Animals↗
PubMed1977

Effects of a plasticizer leached from polyvinyl chloride on the subhuman primate: a consequence of chronic transfusion therapy.

The effects of di-2-ethylhexyl phthalate (DEHP) on hepatic function and histology were evaluated in the rhesus monkey undergoing chronic transfusion. DEHP was solubilized as a result of leaching by platelets or plasma stored in polyvinyl chloride (PVC) blood bags. The average cumulative amount of DEHP infused in 1 year was 69.3 mg., or 21.3 mg./kg. Comparable amounts of DEHP are received by patients who undergo chronic transfusions with whole blood, packed cells, platelets, and plasma in the same time period. Four of the seven PVC-transfused monkeys had abnormal 99mTc liver-spleen scan ratios, four of the seven demonstrated abnormal BSP clearance, and six of the seven had abnormal liver histopathology upon completion of transfusion therapy. These findings persisted in a majority of the monkeys throughout the follow-up period. DEHP persisted in the tissues for up to 14 months after transfusion. The nontransfused monkeys and those transfused with platelets processed in polyethylene containers were normal.

Animals↗
PubMedDate not supplied

Normal growth in high-risk hyperlipidemic children and adolescents with dietary intervention.

OBJECTIVE: The aim of this study was to assess the safety and efficacy of lowering dietary intake of total fat, saturated fat, and cholesterol in growing children and adolescents with severe hyperlipidemia. STUDY DESIGN: This is a 3-year follow-up study conducted on a sample of convenience at three pediatric referral centers in New York City and its suburbs. Subjects were 138 children and adolescents 2 to 15 years of age (54% male), who had been referred with a diagnosis of hyperlipidemia. Those selected had total serum cholesterol values greater than the 95th percentile for age and had at least three visits over 3 years. They were placed on diets restricting total fat content to 30% of total calories and saturated fat to 10% of total calories (National Cholesterol Education Program Step I diet). Anthropometric measures, lipid profiles, and dietary assessment were obtained at each visit. Anthropometric data were analyzed by sex and age. Z scores for height and weight were calculated from NHANES II data and were compared by paired t tests (Hamill et al., 1979, Am J Clin Nutr 32:607-29). RESULTS: Total serum cholesterol dropped from 262 mg/dL at baseline to 249 mg/dL at 3-year follow-up (P = 0.003). There was no significant change in height or weight percentile, expressed as Z score, from baseline to 3-year follow up. CONCLUSIONS: In this population the supervised dietary interventions resulted in a sustained improvement of the lipid profile, with no demonstrable adverse effect on growth.

Adolescent↗
PubMedDate not supplied

Rhesus monkey platelet kinetics and storage.

Rhesus monkey platelets that are separated, 51Cr labeled, and transfused provide yields, 1/2 time and survivals similar to those obtained in man. Rhesus platelets prepared and stored at room temperature for three days have 93 per cent of the yield of fresh platelets. When prepared and stored at 4C, the yield is only 54 per cent of fresh platelets. Rhesus repeatedly transfused with platelets from random unmatched donors always have a significant decrease in the platelet 1/2 time and survival. This was observed after the second homologous transfusion in one and after the third in others. The rhesus provides an excellent platelet model with thrombocyte responses mimicking those of man.

Animals↗
PubMedDate not supplied

An in vitro evaluation of a new plasticizer for polyvinylchloride medical devices.

The rate of Hatcol-200 (H-200) leaching from polyvinylchloride (PVC) by serum is one-hundredth that of di-2-ethylhexyl phthalate (DEHP) as determined by radioassay. There is a proportional decrease in leachability of DEHP but not of H-200 as the plasma proteins are diluted. Saline extracts of DEHP demonstrated a low but progressive rate of leaching with an accumulation of 11 microgram/ml after seven weeks whereas H-200 showed only a constant residue of 0.35 microgram/ml. Normal human serum incubated for three weeks at 37 C with PVC strips plasticized with DEHP produced significant growth-inhibition of human diploid fibroblasts. Human serum incubated in an identical manner with PVC plasticized with H-200 for up to four weeks demonstrated no effect on tissue culture. These studies indicate that H-200 deserves further evaluation as a replacement for DEHP in PVC biomedical devices.

Diethylhexyl Phthalate↗
PubMedDate not supplied

The effects of irradiation on blood components.

The functional properties of formed elements of whole blood were studied following irradiation doses of 500 to 20,000 rads. Irradiated lymphocytes retained only 1.5 per cent of their 3H thymidine uptake after a 5,000-rad exposure and none after 7,500 rads. Red blood cells stored for 21 days and then irradiated with 5,000 rads had the same survival as nonirradiated controls. In contrast, 5,000 rads reduced platelet yields. However, transfused irradiated platelets produced the expected increases in platelet counts and controlled hemostasis in thrombocytopenic patients. After 5,000 rads, granulocytes had normal bacterial killing capacity, chemotactic mobility, and normal superoxide production after high-dose stimulation. Nitroblue tetrazolium reduction and ingestion stimulated by complement opsonized oil droplets were not diminished by 5,000- and 10,000-rad irradiation. The functional qualities of cellular blood components other than lymphocytes are not compromised by 5,000 rads. This irradiation dose may be an effective means of controlling incidence of graft-vs-host disease in immunosuppressed patients.

Blood Cells↗
PubMedDate not supplied

Comparison of corneal epithelial wound healing after photorefractive and lamellar keratectomy.

BACKGROUND: The rate of corneal epithelial wound healing may be determined, in part, by the characteristics of the stromal surface. The excimer laser has the ability to produce a highly uniform ablated surface, which may facilitate reepithelialization after photorefractive keratectomy (PRK). METHODS: The rate of corneal epithelial wound healing after excimer laser PRK was compared with the rate of reepithelialization after manual lamellar keratectomy. Ten rabbits received a 4-mm diameter ablation in one eye (fluence = 160 mJ/cm2) and a shallow, 5-mm diameter, manual lamellar keratectomy in the contralateral eye. At 0, 4, 8, 12, 24, 36, 48, 60, and 72 hours after wounding, sodium fluorescein was instilled, and photographs were taken, converted to video images, and digitized. Wound area was calculated for each time point and converted to wound radius; the slopes of the wound radius, plotted over time, were compared to determine rates of healing. Scanning electron microscopy was performed immediately after wounding to examine surface regularity. RESULTS: By 24 hours after wounding, corneas that had undergone PRK demonstrated a significantly faster rate of epithelial wound healing compared with eyes that underwent lamellar keratectomy (33.4 +/- 1.9 microns/hr vs 27.8 +/- 1.4 microns/hr, respectively, for 12 to 72 hours) (p < 0.0001). Scanning electron microscopy showed greater stromal surface irregularity in the corneas that had undergone lamellar keratectomy, compared with the laser-ablated corneas. CONCLUSIONS: This study demonstrates that the rate of epithelial wound healing is significantly faster after excimer laser PRK than after lamellar keratectomy in the rabbit. Variations in surface regularity and wound edge profile may contribute to differences in wound healing.

Animals↗