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Biomedical subjects

K Powers

Publications and source records attributed to K Powers.

At least 19 recordsLinked to original sources
PubMed1997

Housing costs for adults who are mentally ill and formerly homeless.

The goal of this study was to evaluate the costs, under two different housing conditions, to the state mental health agency of caring for adults who are homeless and mentally ill. One hundred and twelve clients of the Massachusetts Department of Mental Health, living in psychiatric shelters, were randomly assigned to one of two housing types: Evolving Consumer Households or Independent Living apartments. For the next 18 months each client was followed so that the cost of treatment, case management, and housing could be collected and compared. The authors found that treatment and case management costs did not vary by housing type, but housing costs were significantly higher for those assigned to Evolving Consumer Households. Regardless of original housing assignment, treatment costs were lower for clients who remained where they were originally placed. The authors conclude that providing support for clients that increases housing stability reduces their need for treatment and that independent living arrangements may be a more cost-effective policy choice.

Adult↗
PubMed1997

Exercise mode and gender comparisons of energy expenditure at self-selected intensities.

The purpose of this study was to compare oxygen consumption (VO2) and energy expenditure after 20 min of self-selected submaximal exercise for four modes of exercise. Eighteen subjects (9 male and 9 female) first completed a test of VO2max during treadmill running. On separate days, subjects then completed 20 min submaximal treadmill running (TR), simulated cross-country skiing (XC), cycle ergometry (CE), and aerobic riding (AR) exercise. Total VO2 and energy expenditure were significantly higher for TR than all other modes for both males and females (43.6 +/- 10.4, 39.1 +/- 9.7, 36.1 +/- 7.6, 28.4 +/- 6.1 LO2, for TR, XC, CE, and AR, respectively, P < 0.0001). For males and females, heart rate was similar during TR and XC and lower during CE and AR (154.8 +/- 14.2, 152 +/- 13.1, 143.4 +/- 14.9, and 126.2 +/- 12.0 beats.min-1 for TR, XC, CE, and AR, respectively, P < 0.0001). Compared with females, males had significantly greater VO2 (P < 0.005) and energy expenditure (P < 0.004), while females had higher heart rates (P < 0.003). Ratings of perceived exertion (RPE) were not different between TR, XC, and CE, but were significantly lower during AR (13.4 +/- 1.3, 13.6 +/- 0.8, 13.2 +/- 0.9, and 12.6 +/- 1.0 for TR, XC, CE, and AR, respectively, P < 0.003). TR elicited the greatest VO2 and energy expenditure during self-selected exercise despite and RPE similar to XC and CE. Therefore, treadmill exercise may be the modality of choice for individuals seeking to improve cardiorespiratory endurance and expend a larger number of kjoules.

Adult↗
PubMed1997

Outpatient use of left ventricular assist devices: nursing, technical, and educational considerations.

Improvements in technology and in the selection, care, and treatment of patients have led to wider clinical use of mechanical circulatory support. Considerable progress has been made with the use of left ventricular assist devices. Patients are currently maintained in outpatient facilities until a donor heart becomes available; recently, left ventricular assist devices have started to be used as permanent implants. This article outlines the steps that are taken to prepare the patient, the patient's family, and the medical staff for discharge from the hospital of a patient supported with a left ventricular assist device. Extensive technical and clinical training of the primary caregiver and the patient is required to prepare for discharge from the hospital. Data are rapidly accumulating that show that left ventricular assist devices are safe and efficacious for outpatient use. Similar success is expected in clinical trials of permanent left ventricular assist devices, suggesting that many more patients will benefit from this technology in the future.

Heart-Assist Devices↗
PubMed1996

Use of mental health services by formerly homeless adults residing in group and independent housing.

OBJECTIVE: The study examined patterns of mental health service use among 112 formerly homeless mentally ill adults to determine whether clients in a staffed group living situation would need fewer types of services or lesser amounts of some services than those living independently in single apartments. METHODS: Clients in the Boston McKinney demonstration project were randomly assigned to two housing types: individual apartments or a group living situation designed to teach residents to manage the house and their own affairs with minimal staff presence. The types and amounts of services these clients used during an 18-month period were documented and compared. RESULTS: Service use by all clients was heavy, especially use of inpatient psychiatric services. It did not differ by housing type. The large majority of clients in both housing types were able to remain housed and avoid homelessness. Clients who did not stay in assigned housing for the duration of the study had higher levels of inpatient service use, including detoxification and substance abuse treatment. CONCLUSIONS: When homeless mentally ill adults are provided permanent housing and accessible mental health treatment and specialized social services, they are likely to avoid unstable housing patterns, which are associated with higher use of inpatient services.

Activities of Daily Living↗
PubMed1996

Milk-alkali syndrome induced by 1,25(OH)2D in a patient with hypoparathyroidism.

Milk-alkali syndrome was first described 70 years ago in the context of the treatment of peptic ulcer disease with large amounts of calcium and alkali. Although with current ulcer therapy (H-2 blockers, omeprazole, and sucralfate), the frequency of milk-alkali syndrome has decreased significantly, the classic triad of hypercalcemia, alkalosis, and renal impairment remains the hallmark of the syndrome. Milk-alkali syndrome can present serious and occasionally life-threatening illness unless diagnosed and treated appropriately. This article presents a patient with hypoparathyroidism who was treated with calcium carbonate and calcitriol resulting in two admissions to the hospital for milk-alkali syndrome. The patient was successfully treated with intravenous pamidronate on his first admission and with hydrocortisone on the second. This illustrates intravenous pamidronate as a valuable therapeutic tool when milk-alkali syndrome presents as hypercalcemic emergency.

Aged↗
PubMed1994

Travel Illness and the Family Practitioner: A Retrospective Assessment of Travel-Induced Illness in General Practice and the Effect of a Travel Illness Clinic.

As the recognition of the discipline of Travel Medicine grows with increased international travel, an examination of both the value of pretravel advice as well as the general practitioner's role in preparation for, care during, and diagnosis and treatment after travel is necessary. This study was conducted to determine the incidence of travel-related illness in a typical urban population in Scotland and to examine the efficacy of our pretravel clinic related to reduction of illness, preparedness of our patients for travel, and the effects of our travel clinic on the workload generated by the returning ill in our practice. In this retrospective study, 1568 patients, presenting within a 1-year period from 1992-1993 at a medical practice and 100 patients at a travel clinic were studied. Their morbidity rates and, therefore, the effect of the travel clinic on prophylaxis and pretravel advice were determined. In the practice sample, 42% of travelers became ill while abroad, with 48% of ill travelers returning to consult their family doctor at home. Travelers to Africa and Asia were shown to have the highest rates of illness. Travel clinic attendees were more likely to be traveling to high-risk destinations, but were better prepared, experiencing a significantly lower rate of illness during travel (22%). Clinic attendees were less likely to consult their doctor on return home, preferring instead to resolve their illness by self-medication. The results suggest that travel clinics significantly reduce the morbidity of illness for travelers and that the burden on general practices could be reduced with the pretravel advice and prophylaxis that travel clinics can provide.

Journal Article↗
PubMed1994

CSF, sagittal sinus, and jugular venous pressures during desflurane or isoflurane anesthesia in dogs.

Previous studies to determine whether desflurane increases cerebrospinal fluid (CSF) pressure are inconclusive because none have included all of the following: multiple doses of desflurane, administration for at least several hours, examination at normo- and hypocapnia, a concurrent comparison group, direct measurement of both intra- and extracranial CSF pressures, and measurement of venous pressures that influence CSF pressure. The present study was designed to determine whether CSF pressure increases during 4.0 h desflurane anesthesia using a study design that included the above elements. Catheters were placed in the lateral cerebral ventricle, cisterna magna, sagittal sinus, and jugular vein of 12 dogs anesthetized with thiopental 12 mg.kg-1.h-1 and halothane 0.5 to 0.8%. Catheter pressures were measured, and the CSF-sagittal sinus pressure gradient and slope of the gradient to CSF pressure relationship were determined during control conditions. Then, 6 dogs were anesthetized with desflurane and 6 dogs were anesthetized with isoflurane, and the same values were determined for 1.0 h at each of four experimental conditions: 0.5 and 1.0 minimum alveolar concentration (MAC) during normocapnia (PaCO2 35-39 mm Hg) and 0.5 and 1.0 MAC during hypocapnia (PaCO2 20-24 mm Hg). CSF and sagittal sinus pressures, but not jugular venous pressure, increased with both desflurane and isoflurane. The greater increase of CSF pressure with 4.0 h desflurane (to 40.2 +/- 12.7 cm H2O) than with 4.0 h isoflurane (to 26.2 +/- 11.5 cm H2O) was attributable to an increase of CSF pressure that was greater during 2.0 h desflurane and normocapnia than during 2.0 h isoflurane and normocapnia, and to an increase of CSF pressure during 2.0 h desflurane and hypocapnia that was similar to that during 2.0 h isoflurane and hypocapnia. The greater increase of CSF pressure during desflurane may have resulted, in part, from increased CSF volume as indicated by a positive CSF-sagittal sinus pressure gradient (in contrast, there was little or no CSF-sagittal sinus pressure gradient during isoflurane) and a steeper slope of the gradient to CSF pressure relationship.

Anesthesia, Inhalation↗
PubMed1994

Effect of mannitol on cerebrospinal fluid dynamics and brain tissue edema.

Mannitol is used widely to decrease intracranial pressure (ICP); however, the mechanism by which this effect occurs is unclear. This study was designed to examine the effects of mannitol on cerebrospinal fluid (CSF) formation rate (Vf), resistance to reabsorption of CSF (Ra), and brain tissue water content (BTWC). Eighteen New Zealand White rabbits were allocated into one of three groups and studied at baseline and at two sequential doses of 20% mannitol: 0.75 g/kg followed by 4.4 mg.kg-1.min-1, and 2.0 g/kg (1.25 g/kg added to the initial dose of 0.75 g/kg) followed by 8.6 mg.kg-1.min-1. In Group 1, closed ventriculocisternal perfusion (VCP) was performed to determine changes in ICP due to mannitol. In Group 2, the increase in CSF osmolality due to mannitol was determined. In Group 3, mock CSF was used for open VCP to determine Vf and Ra. At the conclusion of each study, brain tissue samples were taken for determination of BTWC. Mannitol increased CSF and plasma osmolality. Ra was increased by 104% with the low dose of mannitol and not significantly changed by the high dose. Mannitol decreased BTWC, Vf (by 49% with the high dose), ICP, and hematocrit. The authors conclude that two of the mechanisms contributing to decreased ICP with mannitol are: 1) decreased CSF volume as indicated by decreased Vf, and 2) decreased brain tissue volume as indicated by decreased BTWC.

Animals↗
PubMed1993

A 24-year follow-up of California narcotics addicts.

OBJECTIVE: This study examined longitudinal patterns of narcotics use, other substance use, criminal involvement, morbidity, and mortality among narcotics addicts. DESIGN: A 24-year follow-up study. Data were obtained from admission records and two face-to-face interviews conducted in 1974-1975 and 1985-1986. PARTICIPANTS: Five hundred eighty-one narcotics addicts admitted to the California Civil Addict Program during the years 1962 through 1964. RESULTS: Most of this sample initiated narcotics use before age 20 years and had a mean age at program admission of 25.4 years. In 1974-1975, 13.8% of the sample died and 28.6% tested negative for opiates. Corresponding rates in 1985-1986 were 27.7% and 25.0%, respectively. Substance use and criminal involvement remained high among this sample into their late 40s. In any given year during the 10 years prior to the 1985-1986 interview, less than 10% of the sample participated in community-based treatment programs such as methadone maintenance. Disability, long periods of heavy alcohol use, heavy criminal involvement, and tobacco use were among the strongest correlates of mortality. CONCLUSIONS: The results suggest that the eventual cessation of narcotics use is a very slow process, unlikely to occur for some addicts, especially if they have not ceased use by their late 30s.

Adult↗
PubMed1993

The HPV response is different with constant pressure vs constant flow perfusion.

Hypoxic pulmonary vasoconstriction (HPV) may be manifest in one of two ways: either an increase in the pulmonary artery pressure, or flow diversion away from the portion of the pulmonary bed with reduced conductance. We tested the hypothesis that the magnitude of the HPV response differs under conditions of constant flow perfusion, where pulmonary artery pressure (Ppa) rises during hypoxia, vs conditions of constant pressure perfusion, where Ppa remains constant and flow (Q) is diverted away from the lungs during hypoxia. In isolated, perfused rabbit lungs, the HPV response to four levels of hypoxia (12, 6, 3 and 0% oxygen) was of greater magnitude and more sustained under conditions of constant pressure perfusion as compared to constant flow perfusion. The possible significance of these findings as they relate to interpretation of studies in both the perinatal and mature pulmonary circulation is discussed.

Animals↗
PubMed1992

Characterization of myocardial extracellular ATP receptors by photoaffinity labelling and functional assays.

Extracellular ATP receptors in rat ventricular myocytes were investigated through intact cell photolabelling followed by protein isolation. 8-Azido-ATP (8Az-ATP) was used for labelling under specific conditions determined by parallel functional studies. In those studies ATP-induced cytosolic Ca2+ transients were irreversibly and specifically inhibited by UV-photolyzed 8Az-ATP, but not by 2-azido-ATP (2Az-ATP), even in the presence of high concentrations of phosphonucleotides not affecting myocardial ATP receptors. Under those conditions background labelling is minimized and radioactive 8Az-ATP specifically labels a band of 45-48 kDa on a SDS gel. Labelling under the above conditions in the presence of ATP gamma S or 2-methylthio-ATP (2-meSATP), which are distinct for two functionally different cardiac ATP receptors, shows two different proteins within the same band consistent with the possible labelling of these two receptors.

Adenosine Diphosphate↗
PubMed1992

Anatomy of the renal innervation: intrarenal aspects and ganglia of origin.

The intrinsic innervation of the kidney is described based on studies using ultrastructural, fluorescent, immunocytochemical, and autoradiographic techniques. The efferent sympathetic innervation reaches all the segments of the renal vasculature and to a much lesser extent the tubular nephron. The afferent renal nerves are localized predominantly in the pelvic region, the major vessels, and the corticomedullary connective tissue. The pathways of the renal innervation to the corresponding ganglia, as reported from observations resulting from the combination of axonal transport labeling and immunocytochemical methods, are presented. In the rat the ganglia of origin of the sympathetic efferent innervation include T13-L1 ipsilateral and contralateral paravertebral ganglia and the prevertebral superior mesenteric and celiac ganglia. The sensory afferent innervation presents a different segmental distribution of the dorsal root ganglia for the right and left kidney. For the left kidney, the corresponding ganglia extend from T8 to L2 with the greatest numbers in T12 and T13. For the right kidney, ganglia as high as T6 and as low as L2 harbor neurons innervating the kidney. Current knowledge of the anatomical bases of the function of the renal nerves is discussed.

Animals↗
PubMed1991

Amrinone reduces pulmonary vascular resistance elevated by U46619 in isolated perfused lungs.

The effects of amrinone on pulmonary vascular resistance (PVR) were studied in an isolated, perfused rabbit lung model where all the major determinants of PVR were controlled. In this preparation, the alveolar oxygen and carbon dioxide tensions, vascular pH and vascular oxygen and carbon dioxide tensions, and zonal conditions of the lung and phasic variations of pulmonary artery pressures could be precisely measured and controlled. Measurements of PVR were made by a complete determination of the pulmonary pressure-flow curve and determination of the PVR under identical flow conditions for all studies. This approach allowed a more precise determination of the primary effects of amrinone on normal and elevated PVR than has been previously possible. We found that amrinone in final concentrations of either 4 or 8 micrograms/ml had no effect on basal PVR and no effect on lung water weight to dry ratios. When PVR was elevated by the addition of the thromboxane A2 mimetic U46619, amrinone reduced the PVR by 27% at a final concentration of 4 micrograms/ml and by 74% at a final concentration of 8 micrograms/ml. We conclude that in the doses tested, amrinone has no effects on basal PVR but is able to reduce elevated PVR in a dose-dependent manner. These results are the first to demonstrate clearly that amrinone has the ability to reduce elevated pulmonary vascular tone through a direct mechanism and not through secondary effects on other determinants of PVR such as left atrial pressure (Pla), increased cardiac output with resultant vascular recruitment, or increases in mixed venous oxygen tension. The possible implications for the clinical use of amrinone in situations of elevated PVR are discussed.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1990

Monoaminergic innervation of the rat kidney: a quantitative study.

The sympathetic innervation of the renal tubules and vasculature was characterized by measuring the overlap of accumulations of autoradiographic grains (AAGs) on these structures in autoradiograms of kidney sections from rats injected with tritiated norepinephrine. AAG overlap was used as an indirect measure of the innervation of those structures. The renal vasculature showed x 4.5 more AAG overlap than observed on renal tubules. The greatest amount of AAG overlap occurred on afferent arterioles, followed by efferent arterioles, interlobular arteries, cortical capillaries, arcuate arteries, and renal veins. High concentration of AAGs occurred along the vascular bundles of the outer stripe. In the tubular nephron the proximal tubule had the greatest amount of AAG overlap, followed by the cortical thick ascending limb of Henle, the connecting tubule, the distal convoluted tubule, and the collecting duct. It was found that afferent arterioles had significantly higher mean density of AAG overlap than efferent arterioles for the superficial, midcortical, and juxtamedullary (vascular bundles excluded) renal cortex. There was consistently more AAG perimeter facing the interstitium than overlapping the vasculature. These observations, together with the ultrastructural distribution of synaptic vesicles in varicosities, suggest that the interstitium might be an additional pathway of neurotransmitter access to the effector structures.

Animals↗