Biomedical subjects

H G Davis

Publications and source records attributed to H G Davis.

11 recordsLinked to original sources

PubMed1994

Glutathione S-transferases and P-glycoprotein in normal rat hepatocytes and hepatoma cells: analysis using flow cytometry.

Using indirect immunofluorescence with fluorescein isothiocyanate-conjugated antibodies, in combination with flow cytometry (FCM), we have developed a technique to detect the alpha, mu and pi isozymes of GST in cell suspensions from normal rat liver, and in H4IIE cells, a rat hepatoma cell line. Cell suspensions fixed in 1% paraformaldehyde were observed to require cell membrane permeation with lysolecithin to allow access and binding of antibodies to immunoreactive proteins within the cytoplasm. FCM analysis indicated normal rat hepatocytes to be positive for GST alpha and mu, but not GST pi, and the H4IIE cells to be positive for all three GST isozymes. Further analysis by FCM for the expression of P-glycoprotein (mdr), a membrane-associated protein product of the multidrug resistance gene, showed an association between the presence of GST pi and mdr in the two cell types. Thus, mdr was detected in significant amounts in H4IIE cells, but not in rat hepatocytes. The method described here has potential applications in screening, sorting and further characterisation for GST pi-positive hepatocytes for mechanistic studies during sequential rat liver carcinogenesis, as well as for characterisation of human tumors for the expression of different GST isozymes and P-glycoprotein during therapeutic management.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1993

Clinical correlates of MMPI depression scales.

We investigated whether Scale 2 (Depression [D]) and the Wiggins Content Scale of Depression (DEP) of the Minnesota Multiphasic Personality Inventory (MMPI) have different clinical correlates when only one of these two scales is elevated. According, a group of patients who elevated DEP higher than Scale 2 (DEP > 2) were compared with a group of patients who elevated Scale 2 higher than DEP (2 > DEP). The patients with DEP > 2 were rated as being less severe than the patients with 2 > DEP on the following Brief Psychiatric Rating Scales: Somatic Concern (SOM), Emotional Withdrawal (WDRA), Depressive Mood (DEP), and Blunted Affect (AFF). The patients with DEP > 2 were rated as more severe on Excitement (EXC). The patients with DEP > 2 were more likely to receive the Axis I diagnoses of: bipolar disorder, manic, and alcohol abuse. Schizophrenia was equally probable for patients in the two groups. It appears that these two MMPI scales of depression have different clinical correlates when either one scale or the other is elevated.

Adult↗

PubMed1992

A cross-validation of MMPI-2 substance abuse scales.

We evaluated the efficacy of the Addiction Potential Scale (APS) and the Addiction Acknowledgement Scale (AAS), two new scales designed to assess substance abuse problems with the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), in samples from settings different from those used in their development. Results replicate earlier findings that both scales discriminate between psychiatric and substance abuse samples and do so more effectively than other substance abuse scales designed for use with the MMPI and carried over to the MMPI-2. Results also suggest that APS may be more resistant than AAS to response distortion.

Adult↗

PubMed1987

Effects on energy absorption of orientation and size of animals exposed to 2.45-GHz microwave radiation.

Rat cadavers oriented perpendicularly to the electric field (parallel to the magnetic field) were exposed to 2.45-GHz microwave radiation. The weight of the cadavers ranged from approximately 5 to 320 g and their lengths ranged from approximately 5 to 22 cm. Average, whole-body specific absorption rates (SAR) were measured using calorimetric techniques, and local specific absorption rates were obtained from time-temperature profiles measured with a non-interacting thermistor probe. The average, whole-body SAR decreased gradually from 0.58 mW g-1 per mW cm-2 at 40 g (10.1 cm in length) to 0.38 mW g-1 per mW cm-2 at 320 g (22 cm in length). The average whole-body SAR decreased from 0.81 to 0.34 mW g-1 per mW cm-2 for cadavers ranging in weight from 5 g (5 cm in length) to 30 g, respectively. The local SAR in the brains decreased from approximately 0.95 mW g-1 per mW cm-2 at 40 g to 0.54 mW g-1 per mW cm-2 at 320 g. Between 5 g and 30 g the SARs in the brain varied from 0.52 to 1.11 mW g-1 per mW cm-2. The local SAR in the colon ranged from 1.05 mW g-1 per mW cm-2 to 0.24 mW g-1 per mW cm-2 for weights between 40 and 320 g. In the 5 to 30 g range, the SAR varied from 0.48 to 1.23 mW g-1 per mW cm-2. A comparison of these results with data previously reported for animals oriented parallel to the E-field showed that the average whole-body SARs were larger for animals weighing greater than 40 g when oriented perpendicularly to the E-field. The local SARs in the colon and brain were slightly higher for the parallel orientation in animals weighing greater than 40 g. The average, whole-body and local SARs were significantly higher for the parallel orientation for animals weighing less than 40 g.

Animals↗

PubMed1984

Whole-body and local dosimetry in rats exposed to 2.45-GHz microwave radiation.

Rat cadavers oriented parallel to the electric field were exposed to 2.45-GHz microwave radiation. The weights of the cadavers ranged from approx. 5 to 320 g and their lengths ranged from approx. 5 to 21.5 cm. Whole-body specific absorption rates (SAR) were measured using calorimetric techniques, and local specific absorption rates were obtained from time-temperature profiles measured with a non-interacting thermistor probe (Vitek). The whole-body SARs decreased by a factor of 12 in rat pups weighing 5 g as compared to adult rats weighing 320 g. The local SARs in the colon were slightly higher than the whole-body SARs for animals in the weight range from 40 to 320 g and approx. 2.5 times higher in animals ranging from 10 to 30 g. The local SARs in the brain were two to three times higher than the whole-body SARs for animals ranging in weights from 20 to 320 g. The data show that it is important to measure both whole-body SARs and local SARs when conducting experiments to determine biological effects in order to adequately explain any biological changes and to extrapolate data from different sizes and species of animals.

Animals↗

PubMed1980