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Biomedical subjects

J Stover

Publications and source records attributed to J Stover.

31 records · Page 2Linked to original sources
PubMed1994

Growth of children following the initiation of dialysis: a comparison of three dialysis modalities.

Maintenance dialysis usually serves as an interim treatment for children with end-stage renal disease (ESRD) until transplantation can take place. Some children, however, may require dialytic support for an extended period of time. Although dialysis improves some of the problems associated with growth failure in ESRD (acidosis, uremia, calcium, and phosphorus imbalance), many children continue to grow poorly. Therefore, three different dialysis modalities, continuous ambulatory peritoneal dialysis (CAPD), cycler/intermittent peritoneal dialysis (CPD), and hemodialysis (HD), were evaluated with regard to their effects on the growth of children initiating dialysis and remaining on that modality for 6-12 months. Growth was best for children undergoing CAPD when compared with the other two modalities with regard to the following growth parameters: incremental height standard deviation score for chronological age [-0.55 +/- 2.06 vs. -1.69 +/- 1.22 for CPD (P < 0.05) and -1.80 +/- 1.13 for HD (P < 0.05)]; incremental height standard deviation score for bone age [-1.68 +/- 1.71 vs. -2.45 +/- 1.43 for CPD (P = NS) and -2.03 +/- 1.28 for HD (P = NS)]; change in height standard deviation score during the dialysis period [0.00 +/- 0.67 vs. -0.15 +/- .29 for CPD (P = NS) and -0.23 +/- .23 for HD (P = NS)]. The reasons why growth appears to be best in children receiving CAPD may be related to its metabolic benefits: lower levels of uremia, as reflected by the blood urea nitrogen [50 +/- 12 vs. 69 +/- 16 mg/dl for CPD (P < 0.5) and 89 +/- 17 for HD (P < 0.05)], improved metabolic acidosis, as indicated by a higher serum bicarbonate concentration [24 +/- 2 mEq/l vs. 22 +/- 2 for CPD (P < 0.05) and 21 +/- 2 for HD (P < 0.05)]. In addition, children undergoing CAPD receive significant supplemental calories from the glucose absorbed during dialysis. CAPD, and possibly, other types of prolonged-dwell daily peritoneal dialysis appear to be most beneficial for growth, which may be of particular importance for the smaller child undergoing dialysis while awaiting transplantation.

Adolescent↗
PubMed1994

The impact of HIV/AIDS on adult and child mortality in the developing world.

At the beginning of the AIDS epidemic some observers predicted that this disease would increase mortality so much that it would cause population decline in many countries. Others have said that the mortality impact of AIDS would not be large. This report reviews the evidence available to date in this issue and presents a simple methodology for assessing the magnitude of the impact at the country level, given a few pieces of readily available information. The paper also presents projections of the likely impact of HIV-AIDS on adult and child mortality in the developing world and for a number of specific developing countries.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Changes in the inferior alveolar nerve following mandibular lengthening in the dog using distraction osteogenesis.

Distraction osteogenesis as per Ilizarov was used to lengthen the canine mandible. In this study, physiological and ultrastructural examination of the inferior nerve was performed. Mandibular body corticotomies were performed, and the mandible was distracted 7 mm. The animals were killed 4 weeks after the distraction was completed. Bone formed within the distraction gap in all dogs. There was no statistically significant difference in the jaw-jerk voltage between control and experimental sides. There was a significant difference between the distracted and control nerves in only one area of one nerve.

Animals↗
PubMed1992

Correlation of sperm viability with gamete interaction and fertilization in vitro in the cheetah (Acinonyx jubatus).

Sperm-oocyte interaction in vitro was studied in the cheetah, a species known to produce poor quality ejaculates and to experience low rates of fertility. Twelve female cheetahs were injected (i.m.) with eCG followed by hCG 84 h later. Twenty-four to 26 h post hCG, each was subjected to laparoscopic oocyte aspiration. A sperm motility index (SMI) was calculated for each of 9 cheetah sperm donors that produced ejaculates averaging 41.3 +/- 22.9 x 10(6) motile sperm and 28.4 +/- 4.9% structurally normal sperm. Each ejaculate was used to inseminate cheetah oocytes from 1 or 2 females and salt-stored, domestic cat oocytes. The presence of ovarian follicles (greater than or equal to 1.5 mm in diameter) showed that all females responded to exogenous gonadotropins (range, 11-35 follicles/female). A total of 277 cheetah oocytes was collected from 292 follicles (94.9% recovery; 23.1 +/- 2.2 oocytes/female). Of these, 250 (90.3%) qualified as mature and 27 (9.7%) as degenerate. Of the 214 mature oocytes inseminated, 56 (26.2%) were fertilized, and 37 (17.3%) cleaved to the 2-cell stage in vitro; but the incidence of in vitro fertilization (IVF) varied from 0 to 73.3% (p less than 0.001) among individual males. When oocytes from individual cheetahs (n = 5) were separated into two groups and inseminated with sperm from a male with an SMI greater than 0 after 6 h coincubation versus an SMI = 0 at this time, the mean fertilization rates were 28/44 (63.6%) and 0/37 (0%), respectively (p less than 0.05). Of the 117 domestic cat oocytes coincubated with cheetah sperm, 96.6% contained 1 or more cheetah sperm in the outer half of the zona pellucida (ZP). Although the mean number of cheetah sperm penetrating the outer ZP of the cat oocyte was similar (p greater than 0.05) among all males, there was a positive correlation between the number of sperm reaching the inner half of the ZP and fertilization rate in vitro (r = 0.82; p less than 0.05). Compared to IVF efficiency in the domestic cat and tiger as reported in earlier studies, IVF efficiency in the cheetah is low. Because oocytes from 11 of 12 cheetahs were fertilized in vitro, there is no evidence that the female gamete is incompetent. Although sperm pleiomorphisms may contribute to poor reproductive performance, examination of the data on the basis of individual sperm donors reveals that effective gamete interaction in the cheetah is dictated, in part, by sperm motility.

Animals↗
PubMed1988

Histology of a heifer placentome after interspecies transfer of a gaur embryo.

Histological examination of a single placentome recovered from a Holstein heifer (Bos taurus ) after delivery of a dead 9.5-mo-old gaur (Bos gaurus ) calf revealed failure of proper development of the chorioallantoic villi after interspecies embryo transfer. Macroscopically, the placentome appeared normal in size, its surface was rough, and on crosssection, the penetration of the villi was irregular and very different from the homogeneous penetration in developed cow placentomes. Microscopically, the heifer caruncle had an extensive system of maternal crypts but the villi failed to branch completely and entered only about one half of the available crypt spaces. The epithelial lining of the maternal crypts in the heifer placentome was nearly missing, which was rather unusual for a species of the genus Bos . The overall picture suggested a decreased feto-maternal compatibility, resulting in poor development of the utero-placental contact, retarded fetal growth, and ultimate fetal death.

Journal Article↗
PubMed1987

Ultrastructure of spermatozoa of the white-naped crane.

Spermatozoa of the white-naped crane were examined with the light and electron microscopes. The relatively simple spermatozoa have a small acrosome, a short midpiece, and a flagellum lacking both dense fibers and fibrous sheath. Crane spermatozoa are unique in that the degree of condensation varies among spermatozoa, but in no spermatozoon does chromatin become highly compacted. Incomplete condensation of chromatin may be responsible in part for the variety of sperm head shapes, including elongate, curved, 'S'-shaped, droplet and spherical forms. Crane sperm may provide a system to better understand the mechanism and function of chromatin condensation in spermatozoa.

Animals↗
PubMed1986

Zellweger syndrome: diagnostic assays, syndrome delineation, and potential therapy.

Patients with the cerebrohepatorenal syndrome of Zellweger lack peroxisomes and certain peroxisomal enzymes such as dihydroxyacetone phosphate acyltransferase in their tissues. Deficiency of this enzyme, which is necessary for glycerol ether lipid synthesis, provides a biochemical method for recognizing patients with subtle manifestations of Zellweger syndrome and suggests the utility of exogenous ether lipid precursors as a therapeutic strategy for these children. We describe the results of glycerol ether lipid supplementation to two children, one with classic Zellweger syndrome and 9% of control fibroblast dihydroxyacetone phosphate acyltransferase activity, and one with mild facial manifestations, wide sutures, hypotonia, developmental delay, hepatomegaly, peripheral retinal pigmentation, and 50% of control fibroblast dihydroxyacetone phosphate acyltransferase activity. An increase in erythrocyte plasmalogen levels following therapy was clearly demonstrated in the milder patient, and neither patient showed evidence of toxicity. Evaluation of therapy by comparison to the usual clinical course of Zellweger syndrome was not helpful because of the variability and incomplete documentation of 90 previously reported cases. The literature survey did provide criteria for classic Zellweger syndrome, which include hypotonia with or without deformation of limbs, large fontanels and split sutures, prominent forehead, flattened facial profile with hypoplastic supraorbital ridges, anteverted nares, highly arched palate, cryptorchidism or labial hypoplasia, hepatomegaly or elevated liver enzymes, peripheral pigmentation of the retina, renal cortical cysts, and characteristic neuropathology involving decreased myelinization, abnormal neuronal migration, and sudanophilic macrophages. Less severe patients, as exemplified by our case 2 and others from the literature, will not have all the classic features and can be recognized only by a growing panel of biochemical indicators. Our patient studies illustrate the complexity of designing comprehensive therapy for Zellweger-like conditions, suggest other diseases that may involve peroxisomal alterations, and emphasize the need for multicenter, collaborative studies to evaluate biochemical heterogeneity and therapy of peroxisomal disorders.

Adrenoleukodystrophy↗
PubMed1984

Cardiomyopathy associated with vitamin E deficiency in seven gelada baboons.

Between November 1979 and July 1982, 7 captive gelada baboons (Theropithecus gelada) died; 5 of them died unexpectedly, 1 died after a 4-month history of heart failure, and 1 was anemic and dyspneic for 2 days before death. Of those that died unexpectedly, 1 was anemic and 4 were clinically normal. At necropsy, all baboons had white or pale patches of myocardium. Histologically, fibrosis and acute myocytolysis were observed in the myocardium. Three affected baboons were tested for plasma alpha-tocopherol content and were found deficient. Four unaffected baboons were given vitamin E for 24 months, and plasma alpha-tocopherol content returned to normal. Blood selenium content was determined in 1 affected baboon and was normal.

Anemia↗
PubMed1982

Myopathy in the nyala.

Between January 1973 and June 1981, a total of 21 nyalas (Tragelaphus angasi) died with clinical and/or pathologic evidence of myopathy. The main clinical signs were stiffness, inability to rise, and failure to suckle in newborn fawns. Death usually occurred without premonitory signs of disease. Gross lesions were characterized by white or pale patches of skeletal or cardiac muscle. Histologically, acute degeneration or necrosis and mineralization were commonly observed in skeletal muscle. Acute necrosis of the myocardium with or without arteriolar fibrinoid necrosis was usually found in juvenile animals. Interstitial fibrosis of the myocardium with arteriosclerosis was commonly observed in adults. The plasma alpha tocopherol values of 3 affected nyalas ranged from 0.03 to 0.08 mg/dl (mean, 0.05 mg/dl). Unaffected nyalas from the same herd had a range of 0.09 to 0.24 mg/dl (mean, 0.13 mg/dl), which is low enough to be considered clinically deficient. The blood selenium values of the affected nyalas and other nyalas from the same herd ranged from 0.30 to 0.33 ppm (mean, 0.32 ppm), and were considered normal.

Animals↗