Biomedical subjects

M Meyer

Publications and source records attributed to M Meyer.

At least 379 records · Page 21Linked to original sources

PubMed1994

Relation between myocardial function and expression of sarcoplasmic reticulum Ca(2+)-ATPase in failing and nonfailing human myocardium.

Expression of sarcoplasmic reticulum (SR) Ca(2+)-ATPase was shown to be reduced in failing human myocardium. The functional relevance of this finding, however, is not known. We investigated the relation between myocardial function and protein levels of SR Ca(2+)-ATPase in nonfailing human myocardium (8 muscle strips from 4 hearts) and in myocardium from end-stage failing hearts with dilated (10 muscle strips from 9 hearts) or ischemic (7 muscle strips from 5 hearts) cardiomyopathy. Myocardial function was evaluated by the force-frequency relation in isometrically contracting muscle strip preparations (37 degrees C, 30 to 180 min-1). In nonfailing myocardium, twitch tension rose with increasing rates of stimulation and was 76% higher at 120 min-1 compared with 30 min-1 (P < .02). In failing myocardium, there was no significant increase in average tension at stimulation rates above 30 min-1. At 120 min-1, twitch tension was decreased by 59% (P < .05) in dilated cardiomyopathy and 76% (P < .05) in ischemic cardiomyopathy compared with nonfailing myocardium. Protein levels of SR Ca(2+)-ATPase, normalized per total protein or per myosin, were reduced by 36% (P < .02) or 32% (P < .05), respectively, in failing compared with nonfailing myocardium. SR Ca(2+)-ATPase protein levels were closely related to SR Ca2+ uptake, measured in homogenates from the same hearts (r = .70, n = 16, and P < .005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Lean body mass estimation by creatinine kinetics.

A new technique for estimating lean body mass (LBM) from creatinine kinetics has been developed. It is based on the principle that creatinine production is proportional to LBM and that, in the steady state, creatinine production is equal to the sum of creatinine excretion (urinary and dialytic) and metabolic degradation. This technique was applied to 17 normal subjects, 26 stable, chronic hemodialysis (HD) patients, and 71 stable, chronic peritoneal dialysis (PD) patients. In the HD group, LBM was also determined by bioimpedance in 11 patients and calculated from total body water, measured as the volume of urea distribution of a sterile urea infusion, in 15 patients. In normal subjects and in the PD group, LBM was assessed by creatinine kinetics as well as by bioimpedance, near infrared, and anthropometric techniques. In the HD patients, LBM by creatinine kinetics correlated significantly with LBM from total body water and the bioimpedance technique. There was no statistical difference between the total body water and creatinine kinetics techniques, but the bioimpedance values were systematically higher than those obtained by the kinetic technique. In the PD group and in normal volunteers, LBM values by creatinine kinetics correlated significantly with the other methods but were lower. Forty-seven percent of the HD patients and 66% of the PD patients had significantly lower LBM by creatinine kinetics than expected for their sex and age. Estimation of LBM by creatinine kinetics is proposed as a simple and convenient technique for the routine nutritional assessment of dialysis patients.

Anthropometry↗

PubMed1994

Arthroscopic excision of symptomatic medial plica. A study of 118 knees with 1-4 year follow-up.

We retrospectively reviewed 93 patients (118 knees) treated by arthroscopic excision of painful medial plica. A scoring scale 0-100 was used to evaluate the symptoms. After an average of 2 (1-4) years, 109 of 118 knees had little, if any, pain and the average improvement in the score was 41 points. Thus arthroscopic excision of a painful medial plica can provide lasting and satisfactory relief of symptoms.

Adolescent↗

PubMed1994

[Atlanto-axial Pott's disease. Apropos of a case with review of the literature].

INTRODUCTION: A new case of sub-occipital Potts disease is reported. CASE REPORT: A 26 years old female from Senegal was admitted for cervical pain of three months duration, neck stiffness and left nasal obstruction with Arnold neuralgia. Radiological studies found a C1-C2 rotatory subluxation with an osteolytic erosion of the lateral mass of the atlas and destruction of the left atlanto-axial joint. CT scan and magnetic resonance imaging provided important diagnostic clues. Culture of sinus biopsies showed a mycobacterium tuberculosis. Progressive reduction of the dislocation and immobilization by minerva jacket for six months with prolonged antituberculous chemotherapy provided successful end result. DISCUSSION: A review of the literature found 95 cases reported since the beginning of this century. The mean age was 20-30 years old. A finding of acid resistant bacilli is necessary for diagnosis and requires culture of gastric secretion, expectoration, retro pharyngeal mass puncture and other upper respiratory tract foci. Radiological signs are discussed. Chemotherapy is the mainstay of treatment with immobilization following reduction of the dislocation when present. The removal of abscess is discussed as well as bone grafting by an anterior or more commonly by posterior approach in case of instability.

Adult↗

PubMed1994

The effects of total intravenous anesthesia using propofol, ketamine, and vecuronium on cardiovascular response and wake up time.

Total intravenous anesthesia (TIVA) can be an effective alternative to inhalational anesthesia. Various techniques of TIVA have been associated with significant cardiovascular alterations and prolonged wake up times. The purpose of this study was to determine if TIVA utilizing propofol, ketamine, and vecuronium would provide stable hemodynamics in normotensive ASA physical status I and II patients and allow rapid awakening upon completion of surgery. Anesthesia was induced with propofol 1.0 mg/kg intravenously (IV), followed immediately by ketamine 1.0 mg/kg IV and vecuronium 0.1 mg/kg IV. Anesthesia was maintained by constant infusion of propofol 100-200 micrograms/kg/min and ketamine 17-34 micrograms/kg/min. This combination maintained hemodynamic stability and provided a rapid wake up time in 80% of the 40 subjects. The remaining 20% experienced significant tachycardia and hypertension or premature ventricular contractions. The mean wake up time was 9.7 minutes from time of neuromuscular blocking reversal to time of extubation. TIVA can be accomplished with propofol, ketamine, and vecuronium; however, 20% of patients experienced side effects, which make this method less attractive compared to alternative anesthetic techniques.

Adolescent↗

PubMed1994

Integrated hepatitis B virus X and 3' truncated preS/S sequences derived from human hepatomas encode functionally active transactivators.

The hepatitis B virus (HBV) frequently integrates into hepatocellular genomic DNA during viral infection. Transcriptional transactivators encoded by integrated HBV X and 3' truncated preS/S sequences are known to stimulate gene expression from homologous and heterologous promoters. Here we demonstrate that 21 of 26 (81%) hepatocellular carcinoma tissues/cell lines contain coding sequences for at least one of the two known transactivators. Four integrated X and three preS/S transactivator sequences contained in five isolates from three hepatoma primary tissues or cell lines were used as examples to prove functionality of the encoded transactivators. In one case, where both X and preS/S sequences were present, dissection of X and preS/S transactivator sequences showed independent functionality. The investigation of X- and preS/S-specific RNA and protein expression revealed the existence of carboxyterminally truncated viral-cellular fusion proteins that were able to stimulate gene expression from the c-fos proto-oncogene promoter five- to ten-fold. These results demonstrate that structurally intact HBV transactivator sequences are integrated in the majority of HBV-associated HCCs/hepatoma cell lines. In all tested examples integrated DNAs had retained functionality as transactivators. This data thereby support indirectly the hypothesis of a possible involvement of HBV transactivators in liver cell proliferation and hepatocarcinogenesis.

Base Sequence↗

PubMed1994

Adjustment of cardiac output to step exercise in heart transplant recipients.

The maximal rate of O2 uptake (max VO2) during constant-load exercise is markedly reduced (about 30-50%) in heart transplant recipients (HTX) compared to peak aerobic performance of healthy sedentary controls (CTL). In order to evaluate the role of central and peripheral factors for O2 transport and utilization, breath-by-breath measurements of oxygen consumption (VO2) carbon dioxide output (VCO2), and beat-by-beat determination of cardiac output (Q) by transthoracic impedance cardiography were performed during upright submaximal square-wave cycloergometric exercise (50 W, 5 min) in a group of 21 HTX (age: 44 +/- 8 years; 23 +/- 29 months after transplantation, range 1.3-137 months) and 10 CTL (age: 37 +/- 10 years). The steady-state values (+/- SD) at 50 W for HTX and CTL, respectively, were: (VO2) 1.01 L/min +/- 0.10 and 0.98 L/min +/- 0.05 (NS); (VCO2) 1.07 L/min +/- 0.14 and 0.84 L/min +/- 0.06 (P < 0.01); (Q) 15.6 L/min +/- 5.3 and 12.8 L/min +/- 3.6 (NS). Heart rate (HR) in HTX, after an initial 60-90 s delay, increased linearly with time of exercise up to 122/min +/- 11. The half-time of the readjustment of Q at the onset of exercise was, in HTX and CTL respectively: 52 s +/- 16 and 40 s +/- 17 (NS). In spite of the time lag in the readjustment of HR, the Q on-response in HTX is only moderately delayed, indicating that the increase of stroke volume by augmented preload and the Frank-Starling mechanism at the onset of exercise compensates for the lack of autonomic control of the denervated allograft.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

The accessory bacteriochlorophyll: a real electron carrier in primary photosynthesis.

The primary electron transfer in reaction centers of Rhodobacter sphaeroides is studied by subpicosecond absorption spectroscopy with polarized light in the spectral range of 920-1040 nm. Here the bacteriochlorophyll anion radical has an absorption band while the other pigments of the reaction center have vanishing ground-state absorption. The transient absorption data exhibit a pronounced 0.9-ps kinetic component which shows a strong dichroism. Evaluation of the data yields an angle between the transition moments of the special pair and the species related with the 0.9-ps kinetic component of 26 +/- 8 degrees. This angle compares favorably with the value of 29 degrees expected for the reduced accessory bacteriochlorophyll. Extensive transient absorbance data are fully consistent with a stepwise electron transfer via the accessory bacteriochlorophyll.

Journal Article↗

PubMed1993