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Biomedical subjects

J Mahoney

Publications and source records attributed to J Mahoney.

At least 37 records · Page 2Linked to original sources
PubMed1996

Cellular targets of infection and route of viral dissemination after an intravaginal inoculation of simian immunodeficiency virus into rhesus macaques.

We used the simian immunodeficiency virus (SIV)/rhesus macaque model to study events that underlie sexual transmission of human immunodeficiency virus type 1 (HIV-1). Four female rhesus macaques were inoculated intravaginally with SIVmac251, and then killed 2, 5, 7, and 9 d later. A technique that detected polymerase chain reaction-amplified SIV in situ showed that the first cellular targets for SIV were in the lamina propria of the cervicovaginal mucosa, immediately subjacent to the epithelium. Phenotypic and localization studies demonstrated that many of the infected cells were likely to be dendritic cells. Within 2 d of inoculation, infected cells were identified in the paracortex and subcapsular sinus of the draining internal iliac lymph nodes. Subsequently, systemic dissemination of SIV was rapid, since culturable virus was detectable in the blood by day 5. From these results, we present a model for mucosal transmission of SIV and HIV-1.

Animals↗
PubMed1996

Impaired bile flow and disordered hepatic calcium homeostasis are early features of halothane-induced liver injury in guinea pigs.

To characterize the early events in liver injury produced by halothane, experiments were performed in genetically susceptible guinea pigs 19 hours after halothane exposure. Serum bile acid concentrations were fourfold increased in halothane-exposed animals compared with controls. In isolated perfused liver experiments, livers from halothane-exposed animals did not differ in hepatic oxygen uptake or in perfusion pressure at the end of experiments, but bile flow and biliary bile salt concentrations were reduced. Hepatic calcium content was increased in halothane-exposed guinea pigs compared with controls, and further experiments were performed to explore the reason for this. As determined by infusion of 45Ca to steady-state perfusate concentrations, hepatic calcium clearance was increased in halothane-exposed guinea pigs compared with controls (0.37 +/- 0.06 vs. 0.28 +/- 0.02 mL/min, P < .01). Decreased biliary excretion of calcium was also noted and was entirely attributable to reduced bile flow. However, although decreased excretion contributed to hepatic accumulation of calcium, it was quantitatively less important than enhanced hepatic uptake. As indicated by passage of a bolus of horseradish peroxidase from perfusate into bile, hepatic tight junction permeability was increased five-fold after halothane exposure. It is concluded that cholestasis, as exemplified by reduced bile flow, is an early feature of the liver injury produced by halothane in guinea pigs and is associated with increased tight junction permeability. Although the decrease in bile flow contributes to an early increase in hepatic calcium content, entry of calcium from the perfusion compartment is quantitatively more important.

Animals↗
PubMed1996

Halothane-induced liver injury in guinea-pigs: importance of cytochrome P450 enzyme activity and hepatic blood flow.

The basis for susceptibility to halothane-induced liver necrosis in guinea-pigs was examined. In hepatic microsomes, the following were similar in susceptible and resistant animals: total cytochrome (CYP) P450 (P450), phenobarbital-inducible pathways of mixed function oxidation (androstenedione 6 beta- and 16 beta-hydroxylase activities) and the CyP2E1-catalysed pathway of N-nitrosodimethylamine N-demethylase activity. Similarly, immunohistochemical staining of CYP2E1 protein was equivalent in livers from susceptible and resistant guinea-pigs. Prior treatment with the P450-inhibitors, metyrapone and SKF-525A ameliorated halothane-induced liver damage in susceptible animals. Conversely, in resistant guinea-pigs, stimulation of hepatic CYP2E1 activity by treatment with 4-methylpyrazole produced severe hepatotoxicity after re-exposure to halothane. These results confirm the conclusions of others, that P450-mediated metabolism produces halothane-induced liver necrosis in the guinea-pig model but, as in other work, the data fail to explain why no difference in activity of these enzymes could be found between susceptible and resistant guinea-pigs. To establish whether a differential effect on hepatic blood flow between susceptible and resistant guinea-pigs could explain this paradox, studies were performed using a radiolabelled microsphere technique. The effect of halothane on lowering cardiac output was identical in both groups of animals and halothane significantly reduced hepatic arterial but not portal blood flow. The effect on arterial blood flow was more profound in susceptible guinea-pigs (0.67 +/- 0.17% of injected microspheres) than in resistant animals (0.99 +/- 0.13%; P < 0.005). It is concluded that P450-catalysed metabolism and reduced hepatic blood flow are both necessary to produce halothane-induced liver injury in susceptible guinea-pigs, but it is the effect of halothane on hepatic arterial blood flow that differs between susceptible and resistant animals.

Animals↗
PubMed1995

Complications of free flap donor sites.

A variety of free tissue transfers are available for microsurgical reconstruction. To date little attention has been placed on the donor site, both from the potential for acute complications as well as long-term morbidity. In this review the various types of tissue transfers in different anatomical locations have been assessed for potential problems at the donor site. An assessment system is proposed to better evaluate this problem as well as to allow comparison of the different donor sites.

Abdomen↗
PubMed1995

Cutaneous distribution of the ulnar nerve in the palm: does it cross the incision used in carpal tunnel release?

An anatomical study was performed on the ulnar nerve to determine whether branches are present in the region of the incision for open or endoscopic carpal tunnel release that may be transected or traumatized, resulting in painful neuromata or dysesthetic symptoms. Twenty-four cadaveric forearms were dissected under 3.5-loupe magnification. A palmar cutaneous branch of the ulnar nerve was found in 42% of the limbs. Branches of the nerve were found in the proximity of the incision for carpal tunnel release in 12.5%. The palmar cutaneous branch of the median nerve was present in 92% of the limbs, with 8% having a branch in proximity to the incision. These anatomical findings suggest that injury to the palmar cutaneous branch of the ulnar nerve may be responsible for the "painful scar" more often than the palmar cutaneous branch of the median nerve.

Carpal Tunnel Syndrome↗
PubMed1994

Aggressive fibrous tissue lesions in the upper extremity: treatment and results.

The oncologic and functional results of treatment of aggressive fibromatosis were reviewed in 16 patients. Five had undergone previous resections. Complete surgical excision, the recommended primary treatment modality for aggressive fibromatosis tissue lesions, could only be performed in five patients. Radiation was administered in 13 patients and mainly used when the resection margins were positive. One patient required reoperation for recurrence. Complete detailed follow-up data were available in 15 patients. Functional analysis revealed 11 good-excellent, 2 fair, and 2 poor results using the Enneking classification. Local control was achieved with a combination of surgery and radiation, maintaining good-excellent function in most patients. The local nature of this tumor can be controlled with surgery and radiation while preserving function in the upper extremity.

Adult↗
PubMed1994

Wound-healing complications after soft-tissue sarcoma surgery.

One-hundred and eighty patients undergoing limb-salvage surgery for soft-tissue sarcoma from 1986 to 1991 were assessed retrospectively for risk factors associated with major wound-healing complications. Twenty-three of 137 patients (16 percent) treated with primary direct wound closure sustained complications. In univariate analysis, the cross-sectional area of tumor resection, the use of preoperative irradiation, the width of the skin excision, a history of smoking, and a history of diabetes and/or vascular disease were associated with wound failure. Multivariate analysis revealed that preoperative irradiation (p = 0.04) and resection diameter (p = 0.017) accounted for the risk of complications. Eighteen additional patients were treated empirically with distant vascularized tissue transfer following preoperative irradiation because of concerns regarding potential wound complications. The lower complication rate in this group suggested that vascularized tissue transfer may be beneficial in lowering wound complication rates.

Adolescent↗
PubMed1994

Risk of falls after hospital discharge.

OBJECTIVES: To determine the incidence of falls within the first month after hospitalization and risk factors associated with falling during this period. DESIGN: Cohort study with 1-month follow-up after hospital discharge. SETTING: 370-bed community hospital. PATIENTS: Consecutive sample of 214 patients, aged 70 years and over, hospitalized for medical illness more than 48 hours and discharged to the community. EXCLUSION CRITERIA: terminal illness, neurologic diagnosis, discharge to skilled nursing facility. MEASUREMENTS: Information was obtained at hospital admission, discharge, and 1 month after discharge. Initial assessment included demographic data, vision, mood, pre-admission function, and use of assistive device. Discharge assessment included length of hospital stay, use of assistive device, need for professional help after discharge, medications cognition, and functional status. Patients were assessed 1 month after discharge for history of confusion and falls. Main outcome measure was falls in the first month after discharge. MAIN RESULTS: Twenty-nine patients (13.6%) fell during the month after discharge. Major risk factors for falls included, at discharge, decline in mobility (P = 0.005), use of assistive device (P = 0.002), and cognitive impairment (P = 0.05), and after hospital discharge, self-report of confusion (P = 0.002). Patients who were functionally dependent and needed professional help after discharge had the highest rate of falls (20.2%). In contrast, only 8.4% of independent patients not requiring professional help fell (P = 0.01). CONCLUSIONS: There is a high incidence of falls after hospital discharge, particularly among patients who are functionally dependent. Further study is needed to determine to what extent acute illness and hospitalization may influence falls risk.

Accidental Falls↗
PubMed1993

Aberrant PO2 values in proficiency testing.

We prospectively determined the frequency of aberrant vials of fluorocarbon/buffer used for proficiency testing of measurements of pH, PCO2, and PO2, using 20 duplicate vials from 12 lots of fluorocarbon/buffer and two arterial blood gas analyzers in eight reference laboratories. We defined aberrant vials as vials for which both duplicate measurements differed from the mean value of repeated measurements for the specific instrument (for each lot of testing materials) by > 0.04 for pH, > 10% of the mean or 3.0 mm Hg, whichever was greater, for PCO2; or > 10% of the mean or 6 mm Hg, whichever was greater, for PO2. Four of 1620 vials (0.25%) were aberrant, all based on PO2 measurements (< 70 mm Hg); all would have failed in both American/California Thoracic Societies and College of American Pathologists proficiency programs. The average intra-instrument SDs of repeated measures (range of mean values: pH, 7.181-7.631; PCO2, 12.7-65.9; PO2, 32.5-150.1) were 0.0055 for pH, 0.67 mm Hg for PCO2, and 1.65 mm Hg for PO2. Deliberate contamination of the fluorocarbon emulsion with room air, as might occur during sampling from the vial, indicated that only minor increases in PO2 (e.g., 1.0 mm Hg at PO2 of 56 mm Hg) occur when samples are aspirated. Larger increases in PO2 (mean 7.1 mm Hg at a PO2 of 66 mm Hg) occurred when the syringe samples were contaminated with room air. We conclude that isolated aberrant measurements of PO2 in blood gas proficiency testing attributable to vial contents can occur, but the frequency is very low.

Blood Gas Analysis↗
PubMed1992

A comparison of a two-wheeled walker and a three-wheeled walker in a geriatric population.

OBJECTIVE: There are few data on the effect of walkers on gait and mobility or on comparisons of different walker types. We compared a commonly used 4-legged, 2-wheeled walker and a newer 3-legged, 3-wheeled walker in measures of gait, mobility, and patient satisfaction. DESIGN: Cross-over controlled trial. SETTING: In the Physical Therapy Department of a Veterans Affairs hospital. PARTICIPANTS: Subjects were 15 male and female frail elderly veterans (mean age, 82 years), both inpatients and outpatients, consecutively enrolled from a sample of 35 patients referred to the Physical Therapy Department for mobility problems. Subjects met the following criteria: age 65 or over, ambulatory, no prior use of a wheeled walker, stable medical condition, and informed consent. INTERVENTION: Subjects were evaluated without either walker and with each of the two walkers on a 15-foot walkway and a 60-foot obstacle course. Subjects were asked which walker they preferred. OUTCOME MEASURE: Outcome measures were stride length on the walkway, time on an obstacle course, and walker preference. RESULTS: Stride length was 1.4 inches (3.6 cm) greater with the 3-wheeled walker than with the 2-wheeled walker (P = 0.016 by Wilcoxon signed-rank test). Time on the obstacle course was 16.0 seconds less with the 3-wheeled walker than the 2-wheeled walker (P = 0.002). The 3-wheeled walker was subjectively preferred. CONCLUSIONS: The 3-wheeled walker appears to have a greater positive impact on gait and mobility than the 2-wheeled walker.

Activities of Daily Living↗
PubMed1991

Wound healing complications in soft tissue sarcoma management: comparison of three treatment protocols.

A prospective, nonrandomized comparison of three treatment protocols was undertaken in 45 patients with soft tissue sarcoma designated preoperatively as being at high risk of wound healing complications. All patients underwent complete resection of the gross tumour mass (5 with positive and 40 with negative microscopic margins). Fourteen patients received postoperative adjuvant irradiation (group I), 16 preoperative irradiation (group II), and 15 preoperative irradiation and vascularized tissue transfer to the surgical bed after resection (group III). Major wound healing complications (defined as complications requiring at least 1 further surgical procedure) were lower in group III patients (chi-square = 5.57, P less than 0.03), as was the mean postoperative hospital stay (P less than 0.02, analysis of variance), and the mean number of secondary surgical procedures. Multivariate analysis showed that the only variable influencing length of stay was the use of tissue transfer. Careful intraoperative assessment of the adequacy of resection is essential prior to performing vascularized tissue transfer to ensure that tumour contamination of the donor site is avoided. Since this study is a nonrandomized clinical trial using sequential distribution of patients to the treatment groups, the data should be considered as preliminary, rather than definitive, evidence of the efficacy of vascularized tissue transfer.

Combined Modality Therapy↗
PubMed1991

Evaluation and treatment of blunt renal trauma.

We examined retrospectively the records of 126 patients with blunt renal trauma to determine the criteria for radiological investigations and the imaging study of choice. Of the 3,993 patients admitted to our regional trauma unit during the last 13 years 126 (3.1%) had blunt renal trauma. Mean patient age was 32 years (range 13 to 87 years) and the male-to-female ratio was 3:1. Mean followup was 7 months (median 4 months). Of the patients 72% had a minor renal injury, 17% had a moderate injury and 11% had a major renal injury. Treatment was conservative in 114 patients, while 9 underwent a genitourinary operation. Results were excellent in 87% of the patients and good in 8%, while 5% failed treatment. All patients who had microscopic hematuria without shock had minor injuries. Excretory urograms (IVPs) were normal in 74% and 39% of the patients when performed for minor and moderate renal injuries, respectively. Computerized tomography (CT) was abnormal in all cases when performed, and was more sensitive and specific than an IVP. Therefore, the majority of patients with blunt renal trauma can be treated conservatively with an excellent result. Furthermore, radiological investigations are not needed in those with microscopic hematuria and no shock. When radiological investigations are indicated a CT scan is the imaging study of choice.

Adolescent↗
PubMed1991

Demonstration of increased bone metabolism in melorheostosis by multiphase bone scanning.

The multiphase bone scan features of melorheostosis are presented. Early increased tracer delivery demonstrated by blood pool imaging supports the concept of ongoing accelerated bony metabolism as a cause of tracer uptake within the osteosclerotic lesions of melorheostosis. There is excellent correlation between the scintigraphic and radiographic distribution of these lesions.

Adult↗
PubMed1991

Fractures following limb-salvage surgery and adjuvant irradiation for soft-tissue sarcoma.

In a prospective study, consecutive patients were treated for soft-tissue sarcoma (STS) by wide resection and adjuvant irradiation. Twelve patients had resection of bone to achieve a tumor free margin; five of these patients were left with lower extremity open segmental cortical defects in the high-dose radiation field. Four of the five patients with cortical defects suffered a fracture through the defect more than six months after surgery. Only one of 71 patients not treated with bony resection suffered a late fracture. Patients requiring bony cortex resection for STS of the lower extremity should be considered at risk for late fracture if adjuvant irradiation is prescribed.

Adult↗
PubMed1990

Concurrent Poland's syndrome and gynecomastia: a case report.

Gynecomastia (enlargement of the male breast) is a common occurrence during puberty and usually resolves. Poland's syndrome or hypoplasia of the chest wall is a rare congenital anomaly associated with hypoplasia of the ipsilateral extremity. Simultaneous presentation of gynecomastia and Poland's syndrome in a 26-year-old man increased the extent of asymmetry and the perception of each deformity. Surgical reduction of the enlarged breast greatly reduced the asymmetry, giving a satisfactory result.

Adult↗
PubMed1989

Transferring the cost.

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Community Mental Health Services↗