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Biomedical subjects

A J Porter

Publications and source records attributed to A J Porter.

51 records · Page 3Linked to original sources
PubMed1992

Immunocytochemical survey of putative neurotransmitters in taste buds from Necturus maculosus.

To investigate synaptic mechanisms in taste buds and collect information about synaptic transmission in these sensory organs, we have examined taste buds of the mudpuppy, Necturus maculosus for the presence of neurotransmitters and neuromodulators. Immunocytochemical staining at the light microscopic level revealed the presence of serotonin-like and cholecystokinin-like (CCK) immunoreactivity in basal cells in the taste bud. Nerve fibers innervating taste buds were immunoreactive for vasoactive intestinal peptide-like (VIP), substance P-like, and calcitonin gene-related peptide-like (CGRP) or compounds closely related to these substances. Immunoreactivity for tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) in the taste cells and nerve fibers was absent. These data suggest that serotonin, CCK, VIP, substance P, and CGRP are involved in synaptic transmission or neuromodulation in the peripheral organs of taste. No evidence was found for cholinergic or adrenergic mechanisms on the basis of the absence of immunocytochemical staining for key enzymes involved in these two transmitter systems.

Animals↗
PubMed1992

A comparison of bladder neck incision and transurethral prostatic resection.

Between 1978 and 1988, 108 patients underwent bladder neck incision (BNI) for bladder outflow obstruction. These patients were compared to a similar group who underwent transurethral resection of the prostate (TURP), during the same time period. Only patients with minimal prostatic enlargement (less than 10 g) with prominent bladder necks and small lateral lobes were included in the study. In addition, all patients in the resection group had a resection weight of less than 10 g on the histopathology report. Patients were followed up by means of a posted questionnaire to which 59 patients in the BNI group and 86 in the TURP group responded. Pre-operative and peri-operative data were also collected from these respondents by a retrospective case record review. This found both operations to be safe with low morbidity and mortality. BNI was better than TURP in terms of shorter operation length (P less than 0.017) and shorter duration of catheterization (P less than 0.004). No other peri-operative differences were found. Follow-up results from the questionnaire showed no significant differences in symptoms between the two groups. Similarly, there was no difference in the number of re-operations performed over the 10 year period studied. Patient assessment of their operation was initially favourable in both groups (greater than 80% patient approval) however, both treatment groups experienced a gradual drop in patient approval over the 10 year period. There were no differences in the level of approval between the BNI and TURP groups.

Aged↗
PubMed1991

Digital videofluorography: a new direction in diagnostic imaging.

Accurate information about digital technology is often difficult to obtain because of unrealistic expectations. The development of the digital department is complex and must not be understated. However, we have attempted to show that if a truly committed hospital immediately accepts DVF, this will result in reduced capital and operational costs, as well as lower radiation doses to the patient and operator. We believe this will happen because every major X-ray manufacturer is demonstrating and offering DVF systems, all of which are based on the technology described in this paper. These systems can either be totally integrated into fluoroscopic facilities or be purchased as add-on components to established units. In any event, a modern fluoroscopic facility can cost several hundred thousand dollars, and must last 10 to 15 years. It seems prudent to acquire quality and digital capability so that these units will be adequate in the year 2000 and beyond.

Attitude of Health Personnel↗
PubMed1988

Transplacental teratogenesis and mutagenesis in mouse fetuses treated with cyclophosphamide.

We studied transplacental fetotoxicity, teratogenicity, and mutagenicity in Swiss Webster mice following different doses of cyclophosphamide (CP; 0, 5, 10, 15, or 20 mg/kg), a well-known mutagen/teratogen, on day 12 of gestation. The fetal survival and weight on day 18 of gestation decreased significantly with increasing CP dose (P less than 0.01). The CP-treated fetuses were also dysmorphic (e.g., shortened limbs, digital defects, cleft palate, open eyes, and hydrocephaly) and the percentage of dysmorphology increased with increasing CP doses (P less than 0.01). To evaluate mutagenesis, a separate group of females received 5-bromodeoxyuridine tablet (50-mg) implants on day 12 of gestation and a CP treatment 8 h later. Fetal liver cells were harvested 24 h post-BrdU implant to analyze sister chromatid exchange (SCE) frequency and micronuclei. CP caused a significant increase in the SCEs per fetal liver cell from 3.4 +/- 0.02 (control) to 90.0 +/- 0.04 (20 mg/kg CP) (P less than 0.01). The increasing CP dose was also related to an increase in micronuclei. The data suggest that CP is transplacentally toxic, teratogenic, and mutagenic. Further analyses of the data suggest that the mutagenic effects of CP may in fact contribute indirectly to the CP-related teratogenic effects. Such conclusions are based on path analysis with directional causations associated with SCEs per cell and the dysmorphic features studied.

Abnormalities, Drug-Induced↗
PubMed1988

Toxicity and sister-chromatid exchange in cultured preimplantation mouse embryos exposed to serum from cyclophosphamide-treated rats: possible implications for testing maternal serum genotoxicity.

We have worked out a simplified method to detect embryotoxicity associated with blood serum. Here we report results for serum from female rats treated with 0, 25, 250 and 500 mg/kg cyclophosphamide (CP) as a control experiment in order to evaluate the feasibility of this protocol. Eight-cell mouse embryos were cultured for 48 h in medium supplemented with 10% rat serum and 10(-6) M 5-bromodeoxyuridine (BrdU). Colchicine (0.2 microM) was added 3 h prior to harvesting the cells for chromosome preparation, and differentially stained sister chromatids were visualized after fluorescence-plus-Giemsa staining. Rats treated with increasing doses of CP yielded serum which had increasing mutagenic [as evaluated by sister-chromatid exchange (SCE)] and toxic effects on mouse embryos during 48-h in vitro cultures. The SCEs/cell (based on 40 chromosomes) ranged from 17.6 +/- 0.31 (mean +/- SE) for serum from control (0 mg/kg CP) rats to 40.4 +/- 0.22 for serum from rats given 250 mg/kg CP. Serum from rats treated with 500 mg/kg CP was essentially lethal on mouse embryos. The percentage embryo survival decreased from 79.8 +/- 0.31% (mean +/- SE) for serum from control rats to 8.4 +/- 0.42% for serum from rats given 500 mg/kg CP. These results indicate that after appropriate testing, this protocol could be used for the possible detection of embryo genotoxicity associated with any human serum. If successful, the evaluation of mouse embryo survival and SCE in the presence of human female sera could become an 'early warning' system for possible reproductive problems (e.g. recurrent abortions, low birth weight and malformations) of unknown aetiologies.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Evaluation of serum-associated embryotoxicity/mutagenicity in females with reproductive dysfunctions using preimplantation mouse embryos in vitro.

Reproductive failures may be caused by chromosomal anomalies, complex interactions of maternal/fetal genotype and environmental factors. Some of them have also been attributed to undefined maternal serum factor(s). We have developed an assay to evaluate maternal-serum associated embryotoxicity/mutagenicity using the preimplantation mouse embryo. It is based on in vitro culture of 8-cell mouse embryos for 48 h in the presence of 10% sera from females with reproductive dysfunction along with suitable controls. The human sera were obtained from three groups of females: (i) with normal reproductive histories (negative controls), (ii) undergoing cancer chemotherapy (positive controls), and (iii) with a history of failing to achieve or maintain pregnancy (test group). The preimplantation mouse embryos were cultured in the three types of human sera and female rat serum (as an internal control for each experiment) and evaluated for toxicity (embryo survival) and mutagenicity (as measured by SCE). Embryos cultured in serum from women with normal reproductive histories and female rats had survival rates of 70.8 +/- 4.3 and 78.9 +/- 0.9%, respectively. The SCE frequencies for these two sera types were similar: 15.7 +/- 0.2 SCEs/cell (rat) and 16.3 +/- 0.3 SCEs/cell (human). Mouse embryos cultured in medium supplemented with serum from females undergoing chemotherapy had significantly (P less than 0.01) reduced survival (33.7 +/- 5.2%) and significantly (P less than 0.01) increased SCEs/cell (26.5 +/- 0.6). The effect of sera from women with histories of reproductive failures on preimplantation mouse embryos was variable and individual specific. Approximately 40% of the test group female sera yielded survival and SCEs/cell comparable to the sera from patients undergoing chemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Spontaneous↗
PubMed1987

The detection of early breast cancer: three-year results from a diagnostic breast clinic.

The initial results from a diagnostic breast clinic in which clinical examination, x-ray mammography and ultrasound are used to establish a diagnosis during a single patient-visit are described. In 3461 patient-visits, 82 histologically-proven breast cancers were detected. Fifty-two per cent of these cancers were 2 cm or less in diameter and 61% had no axillary lymph-node metastases. Fifteen cancers were impalpable lesions which were detected by mammography alone. The over-all malignant-to-benign biopsy ratio was 1:2.7; for impalpable tumours, this ratio was 1:3.9. The role of such a diagnostic breast clinic is discussed, and attention is drawn to a relatively low attendance of women in the "high-risk" age group of over 50 years of age.

Age Factors↗
PubMed1974

Pineal tumors.

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Adolescent↗