Search PubMed⌕ Search

Biomedical subjects

K Powers

Publications and source records attributed to K Powers.

32 records · Page 2Linked to original sources
PubMed1990

Longitudinal patterns of alcohol use by narcotics addicts.

Longitudinal patterns of alcohol use by narcotics addicts sampled from a drug-free treatment program and from several methadone maintenance treatment programs were examined. Overall, a high prevalence of alcohol use was found in both samples across several stages of the addicts' careers. Many addicts were also using nonnarcotic drugs and marijuana concurrently. Generally, levels of alcohol, as well as of other substances use, decreased as the narcotics addiction career began. Unlike other drug use, however, only alcohol consumption increased whenever a decrease occurred in narcotics use. Effects of ethnicity, gender, parental alcohol problems, and opiate and alcohol use onset sequence on the alcohol- and narcotics-related behavior are examined in detail. A pattern of early onset of heavy alcohol consumption before initial narcotics addiction was more common among Chicanos and was associated with a positive parental alcohol history. Women addicts typically had a much lower alcohol consumption level than their male counterparts. Among the 160 deaths of the original 581 addicts followed during the 20 years of the study, alcohol-related deaths accounted for 17.5% of the total. Treatment implications for addicts with an alcohol problem are discussed.

Adolescent↗
PubMed1989

Innervation of the renal proximal convoluted tubule of the rat.

Experimental data suggest the proximal tubule as a major site of neurogenic influence on tubular function. The functional and anatomical axial heterogeneity of the proximal tubule prompted this study of the distribution of innervation sites along the early, mid, and late proximal convoluted tubule (PCT) of the rat. Serial section autoradiograms, with tritiated norepinephrine serving as a marker for monoaminergic nerves, were used in this study. Freehand clay models and graphic reconstructions of proximal tubules permitted a rough estimation of the location of the innervation sites along the PCT. In the subcapsular nephrons, the early PCT (first third) was devoid of innervation sites with most of the innervation occurring in the mid (middle third) and in the late (last third) PCT. Innervation sites were found in the early PCT in nephrons located deeper in the cortex. In juxtamedullary nephrons, innervation sites could be observed on the PCT as it left the glomerulus. This gradient of PCT innervation can be explained by the different tubulovascular relationships of nephrons at different levels of the cortex. The absence of innervation sites in the early PCT of subcapsular nephrons suggests that any influence of the renal nerves on the early PCT might be due to an effect of neurotransmitter released from renal nerves reaching the early PCT via the interstitium and/or capillaries.

Animals↗
PubMed1986

Immunocytochemical localization of renin and kallikrein in the rat renal cortex.

Immunocytochemical studies in the past, using alternate serial sections to localize individual antigens, concluded that there was no close relationship between renin- and kallikrein-containing structures in the rat kidney. We have investigated this relationship by simultaneously localizing renin and kallikrein in the same section using immunoperoxidase with two different chromogens. Analysis of serial kidney sections from three rats indicated that kallikrein-containing late distal tubular cells corresponded in their distribution to connecting tubule cells. They were observed in the proximity (less than 3 micrograms) of renin-containing JG cells in 66.6% of the superficial (N = 30), 46.6% of the midcortical (N = 15) and 26.7% of the juxtamedullary (N = 15) afferent arterioles surveyed. When traced through serial sections, 90% of the afferent arterioles from superficial glomeruli (N = 30), 86.7% of the afferent arterioles from midcortical glomeruli (N = 15) and 73.3% of those from juxtamedullary glomeruli (N = 15) came within 3 micrograms of a late distal tubule showing some kallikrein-positive cells. These cells were adjacent to the afferent arteriole in 67 to 80% of the arterioles surveyed. This spatial relationship suggests an anatomical basis for a possible interaction between the afferent arteriole, containing renin-positive JG cells, and kallikrein-positive late distal tubular cells.

Animals↗
PubMed1985

Innervation of the late distal nephron: an autoradiographic and ultrastructural study.

A study of the monoaminergic innervation of the cortical distal nephron beyond the thick ascending limb of Henle (TALH) was carried out by surveying nine autoradiograms, from three rats injected with exogenous tritiated norepinephrine, for overlapping of the tubule by accumulations of autoradiographic grains (AAGs). The largest number of the AAGs appeared on the late distal convoluted tubule-connecting tubule (LDCT-CNT) portion and the vast majority of the AAGs were related to the afferent arteriole. The distal convoluted tubule (DCT) and cortical collecting duct (CCD) showed half of their AAGs related to the efferent arterioles and capillary-interstitium although a substantial amount was associated with the afferent arterioles or arteries. Electron microscopy of reembedded autoradiograms demonstrated the presence of neuroeffector junctions with the CNT and CCD at sites of AAG overlap. The presence of adrenoceptors in the late distal nephron suggests the possibility of a local response of the nephron to the action of the adrenergic nerves shown in this study.

Animals↗
PubMed1984

Skin tests and blood leukocyte histamine release of patients with allergies to laboratory animals.

Skin tests and in vitro histamine-release reactions were used to evaluate 130 patients observed in an employee allergy clinic at a biomedical research facility. The allergens used included extracts from pollens (ragweed, grasses, trees, weeds), molds, mixed feathers, house dust, cat, dog, mouse, rat, rabbit, guinea pig, and hamster. Of all patients, 66% complained of allergic symptoms on laboratory animal exposure, although only 52% worked directly with animals. Among patients with symptoms, 91% were positive by skin test to at least one laboratory animal, and 46% had asthma. The median length of exposure to laboratory animals before onset of symptoms was 2.8 yr with 60% of the patients developing their symptoms within 3 yr. Among patients who had allergic symptoms before exposure to laboratory animals, 79% were skin test positive to laboratory animals when they were evaluated in this study. There was a close association found between the skin test and histamine-release results with the laboratory animal allergens: 91% of the 4+ skin reactors had leukocytes positive for histamine release versus 5% of the leukocyte donors with less than 1+ skin reactions. A close relationship in positive reactions to different laboratory animal allergens was also found. For example, individuals positive to mouse were positive also to rat (95%), rabbit (79%), guinea pig (83%), and hamster (88%). Patients who reacted to laboratory animals also reacted to some extent to house dust and cat and dog allergens, and about one half of the animal-allergic individuals reacted to pollens. Although nonpollen-allergic individuals can develop sensitivity to laboratory animals, the group at higher risk are allergic individuals, especially those sensitive to house dust, cats, or dogs.

Adult↗
PubMed1984

Innervation of the renal cortical tubules: a quantitative study.

A quantitative assessment of the innervation of the different portions of the cortical tubular nephron in the rat was made using tritiated norepinephrine uptake to label monoaminergic nerves, followed by autoradiography. The proximal tubules (PT) showed the greatest number of innervated profiles (IPs) [i.e., tubular profiles overlapped by accumulations of autoradiographic grains (AAG)] followed by the thick ascending limb of Henle (TALH), the distal convoluted tubule (DCT), and the collecting duct (CD). However, the highest relative frequency of innervation (RFI), i.e., the ratio of the number of IPs to the total number of profiles surveyed, occurred in the TALH followed by the DCT and PT. The number of IPs of the CDs was too low to permit adequate statistical evaluation. The PT showed the largest number of AAGs facing the interstitium or in contact with capillaries, while the TALH had the highest number in contact with the efferent arteriole. The DCT showed a disproportionately high number of AAGs in contact with the afferent arteriole. Our results suggest that all portions of the cortical tubular nephron are under some degree of neural influence.

Animals↗
PubMed1983

The absorption and conjugation of methyldopa in patients with coeliac and Crohn's diseases during treatment.

The absorption and elimination of a single 500 mg dose of methyldopa has been studied after oral administration to 10 normal volunteers, 10 patients with coeliac disease, who were on a gluten-free diet, and to five patients with Crohn's disease. In patients with Crohn's disease the percentage of the dose recovered in urine (24%) was about one-half of normal (50%). This decreased absorption was associated with reduced plasma concentrations of both free and conjugated methyldopa and a decreased pharmacological response. In patients with coeliac disease the percentage of dose recovered in urine (43%) was similar to normals, indicating a normal absorption of the drug. However, the plasma concentrations of both free and conjugated methyldopa were significantly higher than normal, although there was no increase in drug-related effects. These findings confirm the importance of using indices other than drug plasma concentrations in the assessment of bioavailability in disease states.

Adult↗
PubMed1983

Carbon tetrachloride nephrotoxicity in rats with reduced renal mass.

Long-term administration of carbon tetrachloride to rats has produced proteinuria and histopathologic glomerular alterations. The present study was done to determine the effect of prior reduction of renal mass on the long-term nephrotoxicity of carbon tetrachloride. Female Sprague-Dawley rats with uninephrectomy received twice-weekly intraperitoneal injections of either corn oil or corn oil with 0.05 to 0.1 ml carbon tetrachloride. Rats were studied for up to 36 weeks. Increased urinary protein and albumin excretion was noted in the rats receiving carbon tetrachloride after ten weeks. Glomerular abnormalities were noted only in rats receiving carbon tetrachloride. Glomeruli were focally sclerotic with large electron-dense deposits within capillary lumina. Visceral epithelial cell injury was also frequently seen. Tubulointerstitial alterations were also more frequent in animals given carbon tetrachloride. Reduced renal mass may enhance the long-term nephrotoxicity of carbon tetrachloride.

Animals↗
PubMed1978

Morphologic effect of hydantoin drugs on mitosis and microtubules of cultured human lymphocytes.

A new class of mitotic inhibitors is described. Diphenylhydantoin and 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPH), its metabolite, increase the mitotic index of cultured human lymphocytes without affecting the second resting phase (G2). Mitotic inhibition by these compounds is time dependent, and not a property of hydantoins in general. HPPH proved to be more potent than diphenylhydantoin. Electron micrographs of HPPH-treated human lymphocytes showed changes in 45% of the cells in metaphase: a decrease in microtubules or the appearance of 100 A microfilaments. These changes resemble those induced by colchicine.

Cells, Cultured↗
PubMedDate not supplied

Effects of age, menopause, and comorbidities on neurological function of the female genitalia.

The aim of this study was to investigate the effects of age, menopause, and comorbidities on neurological function of the female genitalia using a noninvasive, validated technique. In all, 58 consecutive women were enrolled in the study. Biothesiometry was performed at five genital sites and one peripheral site with S2 dermatome distribution. Kruskal-Wallis one-way ANOVA on ranks was used to evaluate the relationship between age and vibratory sensation. Bivariate and regressional analyses were performed to evaluate the effects of age, menopause and comorbidities on genital sensation. The mean age was 44.6+14.8 y (range 20-78 y). Vibration thresholds increased with advancing age at all six sites. Multilinear regression analysis indicated that menopause and increasing age negatively affect sensation. History of herniated lumbar disc, vaginal delivery, and diabetes variably affected genital sensation. There is a significant increase in vibration thresholds (indicating worsening neurological function) in women as they age and undergo menopause. Biothesiometry is a technique for evaluating genital neurological function in women with coexisting morbidities.

Adult↗
PubMedDate not supplied

Cyanide ingestion: preventing the cascade.

Patients with cyanide exposure present a rare and unique challenge to the critical care nurse. The following article assists the critical care nurse and advanced practice nurse in understanding the pathophysiology of cyanide exposure, assessment of signs and symptoms, and antidotal and supportive therapies. In addition, a case review of nursing care for a patient exposed to cyanide is discussed.

Antidotes↗