Biomedical subjects

J N Scott

Publications and source records attributed to J N Scott.

At least 37 records · Page 2Linked to original sources

PubMed1991

Localization of 125I-atrial natriuretic peptide (ANP) in the rat fetus.

In this in vitro autoradiographic study of ANP-binding sites in fetal rats, 125I-ANP bound to receptors in certain developing neural crest derivatives, including the boundary caps, dorsal root ganglia, and Schwann cells of peripheral nerves. Within the spinal cord, ANP receptors were localized in the roof plate and floor plate. The developing meningeal layer of the CNS, blood vessels, lung, liver, and wall of the herniated gut were also labeled. The topographical and temporal correlation of the appearance of ANP receptors with the developmental processes of the targets suggests that ANP in the fetus is multifunctional, and may be involved in diverse events such as gliogenesis, formation of axonal pathways or surfactant production.

Animals↗

PubMed1991

Beta-amyloid precursor protein gene is differentially expressed in axotomized sensory and motor systems.

The beta-amyloid precursor protein (APP) is involved in the degenerative and regenerative neural changes associated with aging and Alzheimer's disease. We studied the regulation of APP gene expression in a paradigm of degeneration and regeneration, the axotomized rat sciatic system. The sciatic nerves of rats were crushed and at intervals between 4 and 60 days, the affected dorsal root ganglia and spinal cord segments were processed for Northern analysis and in situ hybridization to evaluate various APP mRNA species. After nerve crush, dorsal root ganglia APP mRNA levels are increased for both APP695 (695 amino acids) and APPKPI (Kunitz protease inhibitor). Following reinnervation, APP695 returns to baseline but APPKPI remains elevated. In spinal cord there is a decrease of APP695, which returns to baseline following reinnervation. If regeneration is prevented, the initial phase of post-axotomy response for all APP forms persists for at least 60 days in both dorsal root ganglia and spinal cord. In situ hybridization confirms that the changes are referable to neurons. These findings indicate that neuron-target interactions are important in APP gene regulation; that the APP695 and APPKPI transcripts are differentially regulated following neuronal injury; and that different neuronal populations regulate APP expression in a cell-type specific manner.

Amyloid beta-Protein Precursor↗

PubMed1989

Ontogeny of atrial natriuretic peptide receptors in fetal rat kidney and adrenal gland.

With in vitro autoradiography, specific receptors for atrial natriuretic peptide (ANP) were localized in fetal rat kidney and adrenal glands. Receptors were present over renal vesicles, in the primitive renal medulla and throughout the adrenal gland as early as 16 days gestation. By 20 days gestation, several layers of developing renal corpuscles were present and ANP receptors were localized over developing glomeruli in each layer. Larger accumulations occurred over the juxtamedullary glomeruli. In the medulla, the receptors were localized in a reticular pattern near the pelvis. With emulsion coated sections, ANP receptors in developing renal corpuscles were seen primarily over the lower curve of S-shaped vesicles and around the periphery of the more mature corpuscles. In the renal medulla, receptors were localized over the interstitial cells. In the 16-day-old adrenal gland, ANP receptors were present throughout the cortical area but at 20 days gestation and 1 day postpartum receptors appeared more numerous in the peripheral region. These data suggest that ANP has important developmental effects in the kidney and adrenal gland and may be involved in regulation of body fluid homeostasis in the late gestation rat fetus.

Adrenal Glands↗

PubMed1988

Development of immunoreactive atrial natriuretic peptide in fetal hearts of spontaneously hypertensive and Wistar-Kyoto rats.

The development of immunoreactive atrial natriuretic peptide (ANP) was studied in fetal hearts of spontaneously hypertensive (SHR) and compared to normotensive Wistar-Kyoto (WKY) rats. While SHR fetal hearts were noticeably less developed than those of WKY at 10 and 11 days gestation, both strains showed ANP immunoreactive cells in some but not all primitive heart tubes. At 12 days additional ANP immunoreactive cells appeared in formative trabeculae of the ventricle and atrium. ANP cells were also observed in the myogenic layer of the truncus and bulbus arteriosus and their derivatives from 11 through 16 days, but not at 18 days. In both strains, there were more ANP cells in the left ventricle than in right beginning at day 13. There were no obvious strain differences in the developmental pattern and timing of ANP producing cells. However, on the day of birth, staining was reduced in hearts from some WKY newborn pups compared with hearts from SHR newborns and ventricular staining was reduced in both strains when compared to fetal hearts. These observations indicate that ANP is one of the earliest peptide hormones produced and that the predisposition to genetic hypertension does not appear to influence the development of ANP.

Animals↗

PubMed1988

Disability and dependency in elderly people in residential and hospital care.

Physical dependency and mental impairment were assessed in 143 residents of residential accommodation for the elderly and 125 patients in geriatric continuing-care wards in South Belfast. Although dependency, immobility and incontinence were more common in the hospital patients, there was considerable overlap in the disability levels in the two types of care. There was evidence of dementia in 51% of the residents and 71% of the patients, while 29% of residents and 70% of patients were incontinent. Overall, less than 1% of the elderly population was in each of residential or geriatric hospital care but the proportion rose with age and was greater in older women. About 17% of elderly people in South Belfast with dementia were in residential or geriatric hospital care. The projected increase in the number of oldest people, particularly women, and the increased risk of dementia in this age group, means that the need for residential and continuing hospital care for the elderly will continue to increase.

Age Factors↗

PubMed1988

Psychology of computer use: V. Computer use and the experience of time.

To determine whether estimates of duration are altered when people use computers, 60 undergraduates solved easy or difficult single-solution anagrams presented on paper and by computer. Subjects who solved easy anagrams presented on paper underestimated the duration of time allowed for the task, while subjects who completed the anagrams presented by computer overestimated that duration. Also, subjects who solved difficult anagrams presented on computers solved significantly fewer anagrams than did subjects who solved difficult anagrams presented on paper. Results are discussed in terms of contradictory results of past research regarding perceived complexity of events in intervals and the interaction of task type and time estimation.

Data Display↗

PubMed1987

Distribution of atrial natriuretic factor in fetal rat atria and ventricles.

An immunohistochemical study of rat fetal hearts at 20 days of gestation revealed the presence of immunoreactive atrial natriuretic factor (ANF) in cardiocytes of the left and right atria as well as in certain cells is the left and right ventricles. In the atria, cells of the adluminal pectinate muscles appear more densely labeled than the more peripheral mural cells. In the ventricles, immunoreactive cells were found only in adluminal cardiocytes of the presumptive trabeculae and papillary muscles. The results indicate that ANF is synthesized in the perinatal heart, and that the presence of this hormone in the ventricular cardiocytes may be of only temporary nature during certain stages of pre- and postnatal development.

Animals↗

PubMed1985

Effect of small doses of aspirin and acetaminophen on total menstrual loss and pain of cramps and headache.

90 women participated in a 4-month study. During the first 2 periods, they took no pain relievers whatsoever; during their last 2 periods they took 2 X 325 mg aspirin, acetaminophen or an identically packaged placebo every 4 h to total 8 tablets during the first 24 h of their periods beginning with spotting. For statistical analysis, periods 1 and 2 were combined and averaged, then compared with periods 3 and 4 combined and averaged. Total menstrual loss in grams, number of days of flow, and pain of cramps and headaches were analyzed by MANOVA for each of the three treatment groups. An ANOVA for each of these variables as well as for daily menstrual loss for the first 3 menstrual days was also performed. The MANOVA for all variables by the three treatment groups failed to show any significant differences. Similarly, ANOVAs for the individual variables failed to indicate significant differences except for the variable pain of cramps (p = 0.0072). The Duncan's Multiple Range Test for pain of cramps showed that the average pain for the placebo group was higher than for either the aspirin or the acetaminophen group, although the means for these two groups were not significantly different. These results indicate that neither aspirin nor acetaminophen in the doses given alter either total menstrual loss or the pattern of loss during the first 3 menstrual days. However, both preparations were found to be more effective than placebo in reducing pain of cramps.

Acetaminophen↗

PubMed1985

Placentas from spontaneously hypertensive rats and control strain Wistar-Kyoto rats.

Placentas from spontaneously hypertensive rats (SHR) were compared to those of control strain Wistar-Kyoto rats (WKY) at 15, 18 and 20 days of gestation using light microscopic techniques. Placental lesions similar to those in pregnant hypertensive women were absent in both strains; however, other abnormalities were noted. Hemorrhage at the lateral edges of the decidua basalis appeared to be more extensive in the SHR than WKY at 15 days. At the same time, bloody vaginal discharges were noted in 18% of the SHR. Leukocytic encapsulation of 20-day placentas with viable fetuses was noted in two SHR dams but not in any WKY. It is thought that these differences may be related to the high maternal blood pressure in the SHR or to hormonal imbalance associated with the stress response in the SHR due to frequent monitoring of blood pressure.

Animals↗

PubMed1984

Umbilical vessels of spontaneously hypertensive rats.

Umbilical vessels of spontaneously hypertensive rats, control strain Wistar-Kyoto rats and rats treated with alpha-methyldopa were compared using the scanning electron microscope and light microscope. Observations with the scanning electron microscope revealed that the venous endothelial cells were relatively flat, giving the luminal surface of the vein a smooth appearance. The nuclear region of the fusiform arterial endothelial cells was responsible for the bumpy appearance of the luminal surface of the artery. Microvilli were a consistent feature of the endothelium in both umbilical vessels. There was no consistent pattern of distribution or density of microvilli within either vessel, but microvilli were more abundant on the luminal surface of the artery than in the vein. The luminal surface of some endothelial cells of the artery had long straight processes which crossed several cells before terminating. Light microscopic observations revealed that the endothelial cells and cells of the tunica intima and media contained an abundance of glycogen. The same layers stained sparsely for acid glycosaminoglycans. Maternal hypertension and treatment of spontaneously hypertensive rats with the antihypertensive drug, alpha-methyldopa, did not result in significant morphological alterations of either the endothelium or tunica media of the umbilical blood vessels.

Animals↗

PubMed1984

Do aspirin and acetaminophen affect total menstrual loss?

Two commonly taken over-the-counter analgesics, aspirin and acetaminophen, were compared for: effect on total menstrual loss, effect on total days of menstruation, and effect in reduction of pain due to headaches and/or menstrual cramps. Drugs were administered during a 4-month study according to a double-blind format. During the first 2 months, subjects ingested no drugs whatsoever during their menstrual periods. During the second 2 months, subjects ingested aspirin, acetaminophen, or placebo at the rate of two 325-mg tablets every 4 h to total 8 tablets per day during the first 3 days of their menstrual periods. Statistical analysis of the first 2 periods compared to the last 2 showed no differences in total menstrual weights. The number of days of menstruation in the placebo group was significantly lower (p = 0.0137) than in its own control or in the other groups. Neither analgesic showed a significant reduction in pain due to headache or cramps, although acetaminophen appeared to be slightly more effective than aspirin in reducing menstrual cramps.

Acetaminophen↗

PubMed1984

The effect of an H1 blocker, chlorpheniramine maleate, on total menstrual loss.

50 subjects participated in a 4-month study of the effects of an antihistamine on total menstrual loss. During the first 2 periods, no drugs were given; during the last 2 periods, an antihistamine or a placebo was administered according to a double-blind format. The menstrual weights of the first 2 months were averaged and compared with averages from the last 2 months combined. The treated group showed an average decrease in menstrual loss of 11.30 g compared to a decrease of 0.98 g in the placebo group. While the difference in means was not statistically significant, the variance between the 2 groups was significant (p = 0.0002), indicating that the antihistamine, chlorpheniramine maleate, was effective in reducing menstrual loss in certain individuals, but that the effect was neither uniform nor universal.

Adult↗

PubMed1984

A rapid, noninvasive method for evaluation of total menstrual loss.

Three types of packages containing enough sanitary supplies for one menstrual period were weighed and distributed to 100 subjects to determine adequacy of supplies and compliance to protocol. Returned packages were then reweighed to determine total menstrual loss. No subject used all the supplies in her package; therefore, packages contents were deemed ample. 7 subjects added their own purchased products to their packages; since added products were specified by name, weight corrections were easily made. 2 subjects lost unused supplies which were specified, and weight corrections were made accordingly. Evaporative loss from sealed and stored and frequently opened packages was measured. 100 g distilled water were added to contents inside 60 packages which were sealed and set aside 7 days. Average loss from these packages was 0.65 +/- 0.57 g. 5 g water were added to 60 packages 4 times daily for 5 days (100 g total). Then packages were set aside for 2 days and weighed on day 7. Average loss from these packages was 1.25 +/- 0.85 g. The combination of storage plus frequent opening resulted in an average loss of 1.90 +/- 0.87 g. Thus, the direct-weight method permits recovery of 97-98% of sample.

Adult↗

PubMed1984

Profile of pregnancy in young spontaneously hypertensive rats.

The uterine contents and ovaries of pregnant spontaneously hypertensive rats (SHR) were compared to those of control Wistar-Kyoto rats (WKY). Although there were no strain differences in the number of released oocytes as indicated by corpora lutea, there were fewer viable fetuses in the SHR litters compared to WKY. Since there was no difference in post-implantation intrauterine loss, the lower SHR fetal number was most likely due to fewer successful implantations in the SHR. Maternal blood pressures declined significantly in both strains on day 18 of gestation.

Analysis of Variance↗

PubMed1983

Bone morphology of weanling rats from dams subjected to fluoride.

Femurs of weanling rats from third-pregnancy litters of dams given 150 ppm fluoride in the drinking water were examined by light-and scanning-electron microscopy. Under the conditions of the experimental procedure, no pathological changes were seen in the femurs as a result of maternal ingestion of fluoride. These results indicate that the amount of fluoride crossing the placenta and mammary gland was insufficient to produce significant morphological changes in the bones of 3-week-old rats.

Animals↗

PubMed1983

Fluoride ingestion during multiple pregnancies and lactations: microscopic observations on bone of the rat.

Female rats were given 150 ppm fluoride in the drinking water during three successive pregnancy and lactation periods; the femoral diaphyses were then examined for morphological alterations by light and scanning electron microscopy to determine the influence of fluoride ingestion during multiple pregnancies and lactations. The periosteal surface was dominated by areas of woven bone formation with some prolonged resting areas around osteocyte lacunae. The endosteal surface consisted mainly of areas of active bone resorption with some areas of bone formation. The interior of the cortex was characterized by numerous resorption cavities and remodeling in secondary Haversian systems. Fluoride, by the nature of its incorporation into bone crystals and by its direct cytotoxic effect on bone resorbing cells, reduces the availability of calcium from bone. It appears that fluoride ingestion during lactation created a heightened state of calcium homeostatic stress. As a result, bone mineral was mobilized by resorption of the endosteal surface and by cavitation of the interior of the cortex. Secondary hyperparathyroidism is thought to play an integral part in an attempt to maintain calcium homeostasis.

Animals↗

PubMed1982

Structural features of a specialized region of the epididymis of the Siberian hamster (Phodopus sungorus).

Light and electron microscopic observations of zone six of the Siberian hamster (Phodopus sungorus) epididymis reveal that two distinct tubule populations exist in this region. The population of smaller tubules apparently arises as diverticula of the larger ducts but, though contiguous, the contents of each remain different and separate. While the larger tubules are laden with sperm and seminal fluid, the smaller ones area filled with degenerating cells and cellular debris. Cytologically, the features of the two tubule types are similar. Both display a prominent Golgi apparatus, substantial amounts of rough endoplasmic reticulum, an extensive population of various lysosomal forms and scattered crystalline inclusions.

Animals↗

PubMed1982

Absorptive structures of the mouse yolk sac placenta and associated placental surfaces. A scanning electron microscope study.

Membranes of the visceral and parietal yolk sacs and their adjacent placental surfaces were examined at 13, 18 and 21 days of gestation in the mouse by scanning electron microscopy. The exterior or endodermal surface of the visceral yolk sac was characterized by a villous area attached to the placental disc, a central transition zone, and a smooth distal area. At all days, the abundant microvilli of the villous region were either elongated or bleb-shaped. At 13 days microvilli of cells in the transitional zone and smooth area were uniformly rod-shaped in contrast to the longer microvilli seen at 18 and 21 days; moreover, denuded cells were frequently seen at 21 days. Large squamous endodermal cells on the surface of the placental disc outside the visceral yolk sac were separated by wide intercellular spaces bridged by cytoplasmic processes at all days. Microvilli of these cells were sparse at day 13 but became abundant at day 18 then decreased by day 21. Endodermal cells of the adjacent parietal yolk sac changed from a rounded to a flattened shape from 18 to 21 days, with microvilli being more abundant at 18 days. In contrast to the outer endodermal surface of the visceral yolk sac, the inner mesothelial surface was devoid of villi. At 13 days contiguous edges of cells interdigitated giving the lateral cell borders a microvillous-like appearance. The surface of these cells had a sparse covering of microvilli which became more abundant as the surface was drawn into folds at 18 and 21 days. The adjacent fetal placental surface was covered by flattened cells with few surface specializations. Our observations support an absorptive role for the endodermal surfaces of the visceral and parietal yolk sacs and the associated surfaces of the mouse placenta.

Animals↗