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Biomedical subjects

H Connor

Publications and source records attributed to H Connor.

At least 37 records · Page 2Linked to original sources
PubMed1996

Destruction of Kupffer cells increases survival and reduces graft injury after transplantation of fatty livers from ethanol-treated rats.

This study investigated the role of Kupffer cells on survival and graft injury in transplanted fatty livers from rats treated acutely with ethanol. Donor rats were given ethanol (5 g/kg, by mouth) 20 hours before explantation, and liver grafts were preserved in University of Wisconsin cold storage solution for 24 to 42 hours prior to implantation. Blood samples were taken from the inferior vena cava for 3 hours after implantation. During this time, serum aspartate transaminase levels increased gradually from 122 U/L to 597 U/L in control rats, while ethanol treatment elevated values to 2,278 U/L. Gadolinium chloride (20 mg/kg, given intravenously to recipients 24 hours before explantation), a selective inactivator of Kupffer cells, minimized the increase in aspartate transaminase levels significantly. After implantation of grafts cold-stored for 42 hours, survival rates were 88% in control rats but only 33% in ethanol-treated rats. Gadolinium chloride improved survival nearly to control values. Ethanol nearly doubled white blood cell adhesion, an effect also largely blocked by gadolinium chloride. Further, alpha-(4-pyridyl 1-oxid)-N-tert-butylnitrone radical adducts detected in the bile were increased twofold by ethanol treatment. This effect was also reversed by gadolinium chloride. Taken together, these data indicate that survival is poorer and graft injury is greater in fatty livers from ethanol-treated rats. Inactivation of Kupffer cells minimized graft damage, most likely by improving hepatic microcirculation and diminishing lipid peroxidation.

Analysis of Variance↗
PubMed1995

Expression screening reveals an orphan receptor chick ovalbumin upstream promoter transcription factor I as a regulator of neurite/substrate-cell contacts and cell aggregation.

A rat homologue of chick ovalbumin upstream promoter transcription factor I (COUP-TF I) was isolated using an expression cloning method developed to isolate neurite outgrowth inhibitors. Overexpression of COUP-TF I in 3T3 fibroblasts resulted in reduction of stable contact formation between neurites and transfected cells. Additionally, COUP-TF I enhanced retinoic acid response element-dependent reporter gene expression in 3T3 fibroblasts, indicating that COUP-TF I can modulate transcriptional activation in these cells. Our data suggest that COUP-TF transcription factors are involved in the regulation of cell surface molecules during neruogenesis.

3T3 Cells↗
PubMed1992

Modelling the effect of feeding-related mortality on the feeding strategy of tsetse (Diptera: Glossinidae).

Free-living haematophagous insects risk death through host grooming responses or through increased susceptibility to predation whenever they take a bloodmeal. In this paper we investigate the effects of these risks on the feeding strategy of tsetse. A model is presented that allows for death of tsetse by starvation if they do not succeed in feeding within a fixed time (set at 6 days in the first instance) and for mortality specifically associated with feeding. In addition there is background mortality that applies to all flies at all times. The model is used to compute the individual life-time fertility (number of female puparia per female) as a function of the probability of obtaining a meal (indicated by field data to be very high, usually > 0.85 per day) and the day on which flies start to search for a meal. We suggest that the feeding strategy that would be selected for is that which allows the maximum reproductive output. The model shows that this strategy involves making no attempts to feed for 3-4 days after the previous meal and then attempting to feed with the greatest possible probability until a meal is obtained. The predicted feeding interval, obtained independently of any trapping data, agrees closely with all previous estimates from field studies using a variety of methods. Preliminary results from a laboratory experiment reveal an increased risk of predation of recently fed as compared with hungry tsetse. The lower the actual feeding mortality the more frequently will flies be able to feed should conditions so demand. It is adaptive, however, for tsetse to delay attempting to feed for as long as they can, which is made possible by the near certainty of locating and feeding on a host within 1 day, using their sophisticated sensory systems.

Animals↗
PubMed1989

Mental concentration and the pattern reversal visual evoked response.

The pattern reversal visually evoked response (VER) was recorded using a small check size stimulus. Subjects viewed the VER stimulus with the left eye and a light emitting diode (LED) with the right eye. They were asked to concentrate on either the VER stimulus or the LED. The two targets were arranged so that the left eye remained accurately focused on, and directed to, the center of the VER stimulus throughout the recordings. The VER wave became attenuated when the subject concentrated on the LED. The wave was reduced to around two-thirds of the amplitude present when concentrating on the VER stimulus.

Adult↗
PubMed1989

Grip strength and hand dominance: challenging the 10% rule.

The purpose of this study was to test the utility of the 10% rule in hand rehabilitation. The 10% rule states that the dominant hand possesses a 10% greater grip strength than the nondominant hand. This rule has been used for many years to assist therapists in setting strength goals for patients with injured hands. The sample for this study consisted of 310 male and female students, faculty, and staff from a small, private liberal arts college located in Pennsylvania. Grip strength was measured with a factory-calibrated Jamar dynamometer. Results showed an overall 10.74% grip strength difference between dominant and nondominant hands. This finding verified the 10% rule. However, when the data were separated into left-handed and right-handed subjects, a 12.72% difference for right-handed subjects and a -0.08% difference for left-handed subjects was found. In conclusion, this study showed that the 10% rule is valid for right-handed persons only; for left-handed persons, grip strength should be considered equivalent in both hands.

Adolescent↗
PubMed1987

Comparison of a multiple puncture tuberculin test, 'Imotest', and the Mantoux test in an Australian population.

The new multiple puncture tuberculin testing device, 'Imotest', was compared to the Mantoux test (10 I.U.) in an Australian population. The tests were applied simultaneously to opposite forearms of 105 volunteers. Sixty-eight per cent of the Mantoux tests were positive compared to 39% of the 'Imotests', resulting in a false negative rate of 44% and the difference was highly significant. A further 30 volunteers were tested with a different batch of 'Imotest' and similar results were obtained. When multiple 'Imotests' were applied simultaneously to each of two subjects in a separate study, there was a wide variation of response within each subject, and positive and negative reactions occurred side by side. These results indicate that the 'Imotest' is significantly less sensitive than the Mantoux test and is unsuitable for use as a diagnostic or screening test.

Australia↗
PubMed1983

Comparison of the kinetics and utilisation of D(-)-and L(+)-sodium lactate in normal man.

After infusion of sodium D(-)L(+)-lactate in healthy man the clearance of the D(-)-isomer from blood was 70% of that of the L(+)-isomer. Utilisation of L(+)-lactate may have been inhibited by the presence of the D(-)-isomer. The changes in blood pyruvate concentration and ketone body ratio were compatible with mitochondrial oxidation of D(-)-lactate to pyruvate. After infusion of a D(-)L(+)-lactate racemic mixture, the renal excretion of the D(-)-isomer was much greater than that of the L(+)-isomer, although peak blood concentrations of the L(+) were higher than those of the D(-)-isomer. After infusion of sodium L(+)-lactate, the renal excretion of D(-)-lactate increased 7 times, although no D(-)-lactate could be detected in the blood or in the sodium L(+)-lactate infused.

3-Hydroxybutyric Acid↗