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Biomedical subjects

F Haas

Publications and source records attributed to F Haas.

At least 37 records · Page 2Linked to original sources
PubMed1997

Increased sarcolemmal glucose transporter abundance in myocardial ischemia.

Many clinical and laboratory studies suggest that an increase in glucose uptake and metabolism by ischemic myocardium helps protect myocardial cells from irreversible injury. We have examined whether increased sarcolemmal abundance of cardiomyocyte glucose transporters plays a role in this adaptive response. We have shown that acute myocardial ischemia in perfused rat hearts results in increased sarcolemmal abundance of the major glucose transporter, GLUT4, by causing translocation of GLUT4 molecules from an intracellular compartment to the sarcolemma. In nonischemic control hearts only 18 +/- 2.8% of GLUT4 molecules were on the sarcolemma whereas in ischemic hearts this increased to 41 +/- 9.3%. Insulin also caused translocation of GLUT4 molecules to the sarcolemma, and resulted in 61 +/- 2.6% of GLUT4 molecules on the sarcolemma. The combination of ischemia and insulin did not result in additive increases in sarcolemmal GLUT4 abundance. In more persistent or chronic ischemia, the other major myocardial glucose transporter, GLUT1, appears to play an important role. The mRNA for this transporter, which is constitutively expressed on cardiomyocyte sarcolemma, was increased 2.0-fold in regions of hibernating myocardium in humans with coronary heart disease as well as in persistently hypoxic rat neonatal cardiomyocytes in primary culture. In neither of these conditions was GLUT4 mRNA expression increased. Thus, acute myocardial ischemia increases sarcolemmal glucose transporter abundance mainly by translocating previously synthesized GLUT4 molecules from an intracellular compartment, whereas more chronic ischemia also increases GLUT1 abundance via enhanced mRNA expression. Increased GLUT1 and GLUT4 abundance may participate in the augmented glucose uptake of ischemic myocardium and therefore may help protect ischemic myocardium from irreversible injury.

Animals↗
PubMed1997

Preoperative positron emission tomographic viability assessment and perioperative and postoperative risk in patients with advanced ischemic heart disease.

OBJECTIVES: This study sought to investigate whether determination of tissue viability by means of positron emission tomography (PET) before coronary artery bypass graft surgery (CABG) affects clinical outcome with respect to both in-hospital mortality and 1-year survival rate. BACKGROUND: Patients with coronary artery disease (CAD) and severe left ventricular (LV) dysfunction are at higher risk for perioperative complications associated with CABG. Therefore, the selection of patients who will benefit from CABG is an important clinical issue. METHODS: This study retrospectively evaluated 76 patients with advanced CAD and LV dysfunction (LV ejection fraction < or = 0.35) who were considered candidates for CABG. Thirty-five patients were selected for CABG on the basis of clinical presentation and angiographic data (group A), and 34 of 41 patients were selected according to extent of viable tissue determined by PET (group B) in addition to clinical presentation and angiographic data. RESULTS: There were four in-hospital deaths (11.4%) in group A and none in group B (p = 0.04). After 12 months, the survival rate was 79% in group A and 97% in group B (p = 0.01). Postoperatively, group B patients had a less complicated recovery (p = 0.05). They required lower doses of catecholamines (p = 0.002) and demonstrated a significantly decreased incidence of low output syndrome (p = 0.05). CONCLUSIONS: This retrospective data analysis suggests that selection of patients with impaired LV function on the basis of extent of viability supplementary to clinical and angiographic data may lead to postoperative recovery with a low early mortality and promising short-term survival. Therefore, viability studies permit selection of patients who are at low risk for serious perioperative complications.

Ammonia↗
PubMed1996

Anatomic basis of the lower trapezius musculocutaneous flap.

Differences in the description of the blood supply of the lower trapezius m. and the fact that all former findings are based on very few cases caused us to reinvestigate the arterial supply of the lower trapezius m. Based on the anatomic investigation of 70 human cadavers, the trapezial branch of the dorsal scapular a. was found to be the constant vessel to the lower trapezius m. The origin of the dorsal scapular a., however, was found to be very variable. In 45% it was a direct branch of either the subclavian a. or the costocervical trunk. In the remaining 55% the dorsal scapular a. formed different trunks with the superficial cervical a. and/or suprascapular a. branching off either the subclavian a., the thyrocervical trunk, or the internal thoracic a. Additional segmental musculocutaneous perforators also supply the lower part of the trapezius m. and the overlying skin. Consequently, the lower or ascending part of the trapezius m. has a vascular pattern type V. Thus, the lower trapezius musculocutaneous flap merits consideration in head and neck reconstruction.

Back↗
PubMed1996

Mechanical unweighting effects on treadmill exercise and pain in elderly people with osteoarthritis of the knee.

BACKGROUND AND PURPOSE: People with osteoarthritis (OA) of the knee who have pain generally exhibit decreased activity and physical deconditioning. This study investigated the effects of mechanical unweighting on knee pain and exercise responses in people with OA of the knee who have pain. SUBJECTS: Four men and 23 women, with a mean age of 67.9 years (SD = 11.3, range = 50-88) and having a 12-year average duration of knee OA, participated. METHODS: A mechanical unloading device enabled subjects to perform a modified Naughton treadmill exercise test at 0%, 20%, and 40% of body weight support (BWS). Oxygen consumption (VO2), heart rate (HR), and perceived pain were measured during the last minute of each exercise stage. RESULTS: Mechanical unweighting at 20% and 40% BWS decreased the Vo2 and HR responses to treadmill exercise but did not decrease knee pain during walking in this sample. CONCLUSION AND DISCUSSION: These findings indicate that treadmill exercise accompanied by BWS permits recommended training intensities to be obtained in elderly people with OA, but may not provide pain relief in this group.

Aged↗
PubMed1995

Methicillin-resistant Staphylococcus haemolyticus on the hands of health care workers: a route of transmission or a source?

We undertook a cross-sectional study of hand carriage and environmental contamination of methicillin-resistant coagulase-negative staphylococci on three wards of a single subspeciality surgical service. Sixteen hand cultures from 15 health care workers and 32 environmental cultures were obtained. Of 49 isolates, 35 (72%) were Staphylococcus haemolyticus. This species comprised 14 of the 16 (87%) hand isolates and 21 of the 32 (66%) environmental isolates. Using restriction length polymorphism of total DNA, we identified a single clone of S. haemolyticus on the hands of four health care workers and in the environment at seven locations on two wards. The widespread dissemination of a single clone suggests transmission of S. haemolyticus on the wards and prompts further prospective studies.

Carrier State↗
PubMed1995

Restrictive lung disease following treatment for malignant brain tumors: a potential late effect of craniospinal irradiation.

PURPOSE: To examine the effects of lomustine (CCNU), a commonly used nitrosourea, and craniospinal radiation therapy on the subsequent development of restrictive lung disease (RLD) following treatment for malignant brain tumors. PATIENTS AND METHODS: Pulmonary function testing with measurement of lung volume, spirometry, and diffusion capacity was performed in 28 patients who had received CCNU and/or radiation therapy as treatment for a malignant brain tumor. The median age at the time of treatment was 11.4 years (range, 3.9 to 36.7) and radiation therapy was completed 6 months to 11.6 years (median, 2.6 years) before testing. Patients were divided into four groups based on prior therapy. Group 1 received involved-field irradiation and a CCNU-containing chemotherapy regimen (n = 7); group 2, craniospinal irradiation with a boost to the primary tumor site and a CCNU-containing chemotherapy regimen (n = 6); group 3, craniospinal irradiation with a boost to the primary tumor site and a non-CCNU-containing chemotherapy regimen (n = 7); and group 4, craniospinal irradiation with a boost to the primary tumor site without chemotherapy (n = 8). RESULTS: Fourteen patients (50%) had findings consistent with RLD. One of seven patients (14.3%) who received CCNU without spinal irradiation had RLD, whereas 13 of 21 (61.9%) who received spinal irradiation with or without CCNU had RLD (P = .038), including four of eight patients treated with craniospinal irradiation alone. Logistic regression analysis showed that only spinal irradiation was a significant predictor for RLD. Patients who received spinal irradiation were 4.3 times more likely to have RLD than those who did not receive spinal irradiation. CONCLUSION: Spinal irradiation may be a risk factor for the development of RLD.

Adolescent↗
PubMed1995

Effect of distractive auditory stimuli on exercise tolerance in patients with COPD.

We tested the hypothesis that a distractive stimulus, such as music, introduced during exercise can reduce perception of respiratory effort at any given level of exercise, whereas sensory deprivation increases effort perception. Thirty-six patients with moderate COPD participated in four sessions of symptom-limited exercise. The first session familiarized the subject with the protocol. The other sessions were performed under partial visual isolation while listening to music (M), or to grey noise (GN), or in silence (SIL), presented in randomized order. Subjects graded their respiratory effort using the Borg rating of perceived exertion (RPE) scale. Total exercise time (EXT) and external work (WT) were objective indices of exercise tolerance. EXT was 22% longer with M than with either GN or SIL (p < 0.001), and WT was 44% and 53% greater with M than with GN or SIL, respectively (p < 0.001). These increases occurred at a heart rate that was only a few beats higher than during GN or SIL (104 +/- 3 bpm for M and 101 +/- 3 bpm for GN and SIL), a minimal difference that was statistically significant (p < 0.001). At every level of exercise, perceived exertion with M was lower than for either GN or SIL (p < 0.001). Although the respective RPE was higher for SIL than for GN (p < 0.01) at every level of exercise, WT and EXT were no different. These data indicate that perceived effort can be significantly influenced by external factors. This in turn suggests that the use of distractive stimuli during exercise training programs with patients with COPD may significantly decrease perceived symptoms of respiratory discomfort, thus allowing the patient to exercise to a higher intensity, and potentially achieving more effective exercise reconditioning training.

Acoustic Stimulation↗
PubMed1994

Discrimination of transiently applied mechanical loads: breathing vs. pulling.

Two groups of 24 subjects each attempted to discriminate between large elastic and resistive loads during 50 randomized presentations of each load. Breathers inspired from the loads through a J valve, whereas pullers reciprocally stroked the plunger of a 2-liter syringe connected to the J valve. A range of load durations was obtained in each subject by prematurely unloading approximately one-half of the trials at graded times from their onset. Breathers produced random discrimination scores [50.8 +/- 2.5% (SE) correct] when loaded inspirations were shorter than unloaded inspirations [trials in which both loads induced equal airway pressure (and probably respiratory muscle tension) waveforms] and nonrandom discrimination scores (65.7 +/- 2.8% correct) when loaded inspirations were longer than unloaded inspirations (trials in which both loads induced different waveforms). In contrast, pullers produced nonrandom discrimination scores (62.2 +/- 2.9% correct) when loaded airflow durations were shorter than unloaded inspirations [trials in which both loads induced equal line pressure (and therefore limb muscle tension) waveforms]. Supplemental audio feedback related to instantaneous airflow (an expression of movement) improved load perception in breathers (to 64.2 +/- 3.0% correct; P < 0.01), indicating that airflow feedback introduced load-specific information that was lacking during breathing but redundant during pulling. In support of this hypothesis, airflow feedback by itself enabled a third group of listeners to identify load type with equal accuracy as pullers but with greater accuracy than breathers. These findings suggest that 1) uniformed subjects rely heavily on feedback from airway pressure and/or muscle tension receptors to perceive added loads to breathing and 2) limb mechanoreceptors provide a more sensitive appreciation of movement than do respiratory mechanoreceptors.

Acoustic Stimulation↗
PubMed1994

In the patient's best interests? Dehydration in dying patients.

1. Little is known about the physiological effects of dehydration in terminally ill patients. 2. Terminally ill patients in hospices are not usually given IV infusions. 3. Dying patients not given artificial hydration are less likely to need suction. 4. Hydrating dying patients may add to their distress.

Ethics, Nursing↗
PubMed1993

Use of maximum expiratory flow-volume curve parameters in the assessment of exercise-induced bronchospasm.

Exercise-induced bronchospasm (EIB) is often inferred from the reduction after exercise in one arbitrarily selected value derived from the maximum expiratory flow-volume (MEFV) curve (eg, FEV1) on a single test; however, patients with symptoms of EIB not meeting these criteria may risk being undiagnosed. To assess the ability of repeated tests using additional MEFV parameters in identifying EIB-prone patients, we investigated the effects of exercise provocation on the MEFV curve on two separate occasions. Of 95 patients with symptoms of EIB, 61 had reproducible exercise-induced changes (< 10 percent intraresponse variation), falling into four patterns: 27 (44 percent) had significantly reduced VC and airflow throughout the MEFV curve; 18 (30 percent) had unchanged VC but decreased airflow throughout the curve; 11 (18 percent) had reduced airflow above 50 percent VC but not below 50 percent VC; and 5 (8 percent) had significant reductions in airflow only at 50 percent VC or below. Of the other 34 subjects, 18 had no apparent response, and 16 responded on only one occasion, making objective assessment of these patients' EIB equivocal. We conclude that for a given individual, failure to meet arbitrary criteria does not rule out EIB. Additionally, a more subjective approach that integrates, among other factors, all routine MEFV curve parameters taken from multiple tests with clinical symptoms and history provide a more accurate assessment of EIB.

Adolescent↗
PubMed1992

Serial sectioning of insects with hard exoskeleton by dissolution of the exocuticle.

The method reported here was designed to produce paraffin serial sections as thin as 5 microns of insects or other arthropods with a hard cuticle. Heads and abdomens of Apis mellifera, Eristalomyia tenax and Tenebrio molitor were fixed with Schaffer's liquid, dehydrate with 80% ethanol, 90% ethanol, two changes of 100% isopropanol (2 hr each) and 12 hr in a 1:1 mixture of paraffin (58 C melting point) at 60 C. They were molded in paraffin after 12 hr of infiltration under a partial vacuum at 60 C. Large body openings of objects were sealed with paraffin to prevent infiltration of solvents. Thereafter, the outer paraffin was removed manually and with xylene (15 min); the cuticle was rehydrated with 100% isopropanol and 100% ethanol (15 min each). The objects were then treated with Sputofluol (Merck; a mixture of NaOH and NaClO) until they became white or their colorless endocuticle was stainable with aniline blue WS (C.I. 42755) after rinsing in a 50% acetic acid solution (v/v). They were then dehydrated with 100% ethanol and 100% isopropanol (15 min each) and subsequently re-embedded in paraffin. They were molded, sectioned, stained and mounted as usual.

Animals↗