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Biomedical subjects

R R Harris

Publications and source records attributed to R R Harris.

48 records · Page 3Linked to original sources
PubMed1982

A case-control study of stillbirths at a teaching hospital in Zambia, 1979-80: antenatal factors.

A total of 266 mothers of stillborn babies (cases) and 266 mothers of live-born babies (controls), matched for parity, were studied in an attempt to define the causes of the stillbirths. Altogether, 16% of mothers in the former group were over 35 years old, compared with 9% in the latter; in addition, 16% of cases had a history of past perinatal death, compared with only 2.4% among the controls.Mothers of stillborn babies had fewer attendances at the antenatal clinic and a longer interval between the last visit and delivery, compared with the control group; 8% of the former group had no antenatal care. Only 47% of mothers had a Venereal Disease Research Laboratory (VDRL) test reported before delivery. The VDRL test was positive in 34% of the cases tested and in 7% of controls.Of the 266 stillborn infants, 56% were of low birth weight; 12% of the 170 macerated stillbirths were associated with intrapartum problems that may have contributed to death, compared with 46% of the 96 fresh stillbirths. Prolonged labour and prolapsed cord were the commonest intrapartum factors associated with death. The most common antepartum factors were a positive VDRL test, abruptio placentae, and a history of illness. A total of 5% of the stillborn infants had some congenital abnormality. No cause of death could be identified in 13.5% of these infants, the majority of whom were of low birth weight.

Adult↗
PubMed1981

The effects of alpha and beta adrenergic agonists and cyclic adenosine 3':5'-monophosphate on epidermal metabolism.

Continuously regenerating stratified squamous epithelia form an interesting model for examining mechanisms controlling the balance between rates of cell formation and cell maturation and death. In vitro assays of rates of glycolysis and amino acid incorporation of epidermal sheets free from dermal contamination were used to examine rates of metabolism in both normal and hyperplastic epidermis after treatment with various adrenergic agonists and cAMP. Epinephrine and isoproterenol over the concentration range of 1 x 10(-9) to 1 x 10(-5) M depressed the rates of glycolysis and amino acid incorporation in normal epidermis. Dibutyryl cyclic AMP produced a 73 to 78% depression in metabolic activity and its action was enhanced by the addition of theophylline. The alpha adrenergic agonist norepinephrine produced similar reductions. When epidermal samples were treated with hexadecane to induce a mild hyperplasia, depressant effects of isoproterenol and epinephrine were lost, but dibutyryl cyclic AMP and norepinephrine still reduced metabolic activity. The results suggest that adrenergic agents and their putative second messenger cAMP cause reductions in epidermal metabolic activity, an effect similar to their effects on cell proliferation, and that increased rates of proliferation are associated with loss of beta adrenergic responsiveness of the epidermis.

Alkanes↗
PubMed1980

Four methods of measuring human corneal endothelial cells from specular photomicrographs.

We measured central corneal endothelial cell density and area from contact specular photomicrographs of ten normal and ten abnormal corneas, comparing the precision, cost, and speed of four methods: a rectangle, planimeter, digitizer, and cell sizer. The rectangle, planimeter, and digitizer gave results that differed less than 10% from each other; therefore, the three methods can be used interchangeably for clinical purposes. There are statistically significant differences among the three techniques that may be important in basic research. The cell sizer gave a rapid, less precise estimate of mean cell area and cell density. The planimeter and digitizer measured individual endothelial cell size, and the latter entered data directly into a computer that printed both a copy of the endothelial mosaic and a histogram of cell size frequency, and computed cell density and mean cell area. We make the following recommendations: Count cells in a rectangle used for routine clinical measurement. use a cell sizer for rough estimation, as in an eyebank setting. Use a computerized digitizer to study individual endothelial cell size.

Cell Count↗
PubMed1980

An examination of the relationship between experimentally altered rates of epidermal proliferations and rates of epidermal metabolism assayed in vitro.

Continuously regenerating stratified squamous epithelia form an interesting model for examining mechanisms controlling the balance between rates of cell formation and cell maturation and death. Previous investigations of epidermal metabolism have been mainly based on single enzyme assays which may not form a reliable guide to changing rates of flux through metabolic pathways. Methods for in vitro assays of rates of glycolysis, protein synthesis and RNA synthesis of epidermal sheets free from dermal contamination were developed and used to examine rates of epidermal metabolism after experimental alteration of rates of epidermal proliferation. Starvation resulted in a 45-53% reduction in the in vivo epidermal labeling index and a 49-56% reduction in glycolysis and incorporation of amino acids assayed in vitro. Induction of epidermal hyperplasia with hexadecane resulted in a 4-fold increase in labeling index, a 6-fold increase in vitro glycolysis and a 3 to 4-fold increase in in vitro assays of incorporation of amino acids and uridine. Hyperplastic epidermis also showed an increased rate of incorporation of histidine (a marker for keratokyalin synthesis) relative to leucine (a marker for basal cell protein synthesis) indicating a change in maturation. The results suggest mechanisms linking rates of cell proliferation and death and indicate the possible value of such assays investigating these mechanisms.

Animals↗
PubMed1977

Urine production rate and water balance in the terrestrial crabs Gecarcinus lateralis and Cardisoma guanhumi.

1. The rate of urine production in the terrestrial crabs Gecarcinus lateralis (Freminville) and Cardisoma guanhumi Latreille maintained on s.w.-moist sand was measured by inulin clearance. 2. The inulin U/B ratios in both species rose to about unity after 48 h, and remained at this level. It was concluded that neither species withdrew water from the primary urine. 3. The relatively high rate of inulin clearance in G. lateralis (10-69% body wt day-1) was considerably reduced when animals were transferred to dry sand (2-15% body wt day-1). 4. The rate of water loss on dry sand was measured in G. lateralis and changes in the haemolymph and urine osmolality recorded. 5. The prevention of possible reabsorption of water from voided urine did not appear to affect significantly the rate of water loss in conditions of water deprivation. 6. The maintenance of urine production rates measured on s.w.-moist sand would double the water loss of G. lateralis in dry conditions.

Animals↗
PubMed1975

Metabolic fate of fatty acids in the carnitine cycle of brown adipose tissue mitochondria.

Freshly isolated mitochondria from brown adipose tissue are uncoupled with respect to oxidative phosphorylation. When these mitochondria oxidize[U-minus 14-C] palmitic acid in the presence of malate the label is found in three major fractions. Polar lipids, rich in acyl carnitines, remain in the mitochondrial pellet. A large fraction, rich in tricarboxylic acid cycle intermediates, is exported to the suspending medium, as is a third, smaller fraction containing ketone bodies and beta-hydroxy-beta-methylglutaric acid. Prevention of oxygen uptake by addition of rotenone or antimycin prevents accumulation of cycle intermediates, increases formation of acyl carnitiness and increases beta-hydroxybutyrate relative to acetoacetate. Rotenone and antimycin do not prevent formation of labeled phosphatidylcholine. Partial suppression of oxygen uptake by benzene-1,2,3-tricarboxylic acid, amytal or malonate leads to results between these extremes. Addition of lysophosphatidylcholine had minimal effects on export of cycle intermediates, but increased formation of ketone bodies and particularly of acyl carnitines. The significance of lysophosphatidylcholine as an endogenous modifier of mitochondrial metabolism is discussed.

Adipose Tissue, Brown↗