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Biomedical subjects

A Katz

Publications and source records attributed to A Katz.

At least 379 records · Page 21Linked to original sources
PubMed1987

Computed tomographic findings of brain and skull in myotonic dystrophy.

Twenty-four patients with myotonic dystrophy underwent computed tomographic examination of the skull and brain. The results were compared with those of 20 normal subjects of similar age and sex distribution. Microcephaly and thickening of the calvarium were frequently observed. Some cases showed basal ganglia calcification. Our findings confirm that cranial hyperostosis and brain pathology is a common manifestation of this systemic disease.

Adult↗
PubMed1987

ST elevation in leads V1 to V4 caused by isolated right ventricular ischemia and infarction.

A patient with isolated right ventricular ischemia and infarction is presented. ST elevation in leads V1 to V4 mimicking anteroseptal myocardial infarction was recorded at admission and during episodes of chest pain later on. Noninvasive and invasive workup suggested isolated right ventricular infarction and ischemia due to an occluded small and nondominant right coronary artery.

Arterial Occlusive Diseases↗
PubMed1987

Role of qualitative choriogonadotropin assays in diagnosis of ectopic pregnancy.

We compared the clinical sensitivity and cost-effectiveness of a qualitative assay for choriogonadotropin in human urine ("Icon" hCG) with a quantitative assay of serum from 142 women with pathologically-diagnosed ectopic pregnancy. Results show that although the qualitative assay had a clinical sensitivity for pregnancy of 98.6%, as compared to 100% for the quantitative assay, it was more economical to use, and had a significantly shorter turnaround time. We conclude that qualitative hCG assay of either urine or serum is a good screening method for detecting pregnancy, and can replace the stat quantitative assay in women with suspected ectopic pregnancy. We present a diagnostic algorithm to illustrate the role of qualitative and quantitative hCG assays in conjunction with ultrasonography, culdocentesis, and laparoscopy for diagnosis of ectopic pregnancy.

Algorithms↗
PubMed1987

Quinidine-induced lupus erythematosus-like syndrome: three case reports and a review of the literature.

Three patients with an LE-like syndrome secondary to quinidine are described. Twenty-two similar cases are reviewed. The clinical picture is characterized mainly by polyarthritis, pleuritis, fever and dermatitis. The common laboratory findings are positive antinuclear antibodies, absence of anti-DNA antibodies, thrombocytopenia, leukopenia and abnormal liver function tests. This LE-like syndrome may appear within days or up to several years after the start of quinidine treatment and disappears completely a few weeks after discontinuation of the drug.

Aged↗
PubMed1987

The effect of sodium phenytoin on central nervous system oxygen toxicity.

The effect of sodium phenytoin on hyperbaric oxygen (HBO) induced central nervous system (CNS) toxicity was studied in rats. The latency of the epileptic electroencephalographic discharges was measured in 20 phenytoin-treated rats exposed to 6 ATA of 100% oxygen, and compared with that of 20 saline-injected rats exposed to the same pressure of pure oxygen. No statistically significant difference was found in the latency between the two groups. In addition, phenytoin failed to suppress or to modify the clinical seizures. Sodium phenytoin failed to suppress or to modify the clinical seizures. Sodium phenytoin blood levels were determined in the rats, and were found to be within the therapeutic range. We conclude that sodium phenytoin is ineffective in suppressing HBO induced CNS oxygen toxicity.

Animals↗
PubMed1987

The immediate effect of burn wound excision on pulmonary function in sheep: the role of prostanoids, oxygen radicals, and chemoattractants.

Pulmonary dysfunction is a well-recognized complication of burn wound excision. It remains unclear whether this is caused by bacteria or inflammatory mediators released during excision of the wound. We produced a 15% full-thickness burn in 18 sheep, and between days 5 and 7 completely excised the wound under general anesthesia. Pulmonary parameters of static and dynamic lung compliance (CSTAT and CDYN), PaO2/FiO2, and pulmonary artery pressure (Ppa) were measured, as well as burn lymph, venous and aortic thromboxane B2 (TxB2), chemotactic index (chemotaxis/chemikinesis), and oxygen radical activity reflected in the level of lipid peroxidation in lung tissue. We noted a transient increase in burn lymph and venous TxB2 during excision, increasing from a preburn value of 200 and 220 +/- 50 pg/ml to 950 +/- 210 and 980 +/- 280 pg/ml, respectively. In 13 of 18 sheep, chemotactic activity and lung tissue lipid peroxidation, measured as malondialdehyde (MDA) content, were not increased. In this group only a very transient decrease in CDYN, PaO2/FiO2, and a 3 mm Hg increase in mean Ppa was seen with excision, with these parameters returning rapidly to baseline. Five of the 13 sheep had wound biopsy specimens that were greater than 10(6) organisms/gm tissue. In the remaining five sheep, plasma chemotactic index was also significantly increased with excision, as was lung MDA content, while decreases in CDYN, CSTAT, and PaO2/FiO2 and an increase in Ppa were more protracted. Three of these five sheep had wound biopsy specimens greater than 10(6) organisms/gm. We conclude that a release of thromboxane occurs during excision, which corresponds in time to transient lung dysfunction. If there is also a release of chemotactic factors, a more protracted pulmonary response occurs with evidence of O2 radical-induced lung changes.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

The content of NADH in rat skeletal muscle at rest and after cyanide poisoning.

The concentration of NADH was determined a high-oxidative muscle (soleus) and a high-glycolytic muscle (extensor digitorum longus, EDL) from resting rats. The NADH content of freeze-clamped control muscles was 0.35 +/- 0.04 (mean +/- S.D.) and 0.31 +/- 0.04 mmol/kg dry wt. in EDL and soleus respectively, and increased to peak values of 0.58 +/- 0.05 (EDL) and 0.87 +/- 0.10 (soleus) after 10 min of NaCN treatment. The [lactate]/[pyruvate] ratio, which was not significantly changed in soleus and increased only slightly in EDL after NaCN incubation, shows that only minor changes occurred in the cytosolic NADH concentration. Provided that the major part of muscle NADH is located in the mitochondria it can be calculated that the mitochondrial NADH content in skeletal muscle at rest is about 36 (soleus) and 60% (EDL) of the anoxic value, respectively. These results are in contrast with previous studies with the surface-fluorescence technique, where mitochondrial NAD appeared to be almost completely reduced in resting skeletal muscle.

Animals↗
PubMed1986

Parietal occipital nape of neck flap. A myocutaneous flap for selected head and neck reconstruction.

Reconstruction in head and neck surgery has been greatly advanced with the use of the pectoralis major and trapezius myocutaneous flaps. Most surgical defects can be repaired with one of these flaps alone, or in conjunction with cutaneous flaps. Specific problems, however, occur that cannot be successfully reconstructed by these standard flaps. The traditional scalp flaps are cutaneous flaps. Use of these flaps is limited because of their shortened arc of rotation and accompanying forehead deformity. Three patients underwent reconstruction with a parietal occipital nape of neck myocutaneous flap. Its advantages include the following: large segments of hairless skin from the contralateral side of the neck can be used, an extensive arc of rotation and distance can be achieved with excellent vascularity in the overlying skin, and cosmetic results are superior. Angiographic studies were used to demonstrate the vascular pattern and supply to this flap. Cadaver dissections were performed to determine the pattern of distribution of the perforating vessels to the skin from underlying muscle.

Carcinoma, Squamous Cell↗
PubMed1986

Biochemical investigation of the pathogenesis of Heymann nephritis.

This study describes biochemical comparison of proximal tubule antigens from the brush border membrane (BBM) of dog and rat kidney. The purpose was to determine if a difference in BBM composition could explain the inability to produce either active or passive Heymann Nephritis in the dog. Although the membrane composition as revealed by coomassie blue staining on 4 to 11 per cent polyacrylamide electrophoresis varied considerably between rats and dogs, polyclonal antibodies (rabbit anti-rat, rabbit anti-dog) against purified BBM from both species immunoprecipitated five identical polypeptides. Four bands were visualized between 70 kd and 170 kd; but the major polypeptide had an apparent molecular wt of approximately 460 kd. This high molecular wt constituent and three of the other peptides were bound specifically to lentil lectin column, confirming their glycoprotein nature. Only the 460 kd polypeptide was immunoprecipitated by monoclonal antibody against gp 330. Since both rat and dog BBM contain gp 330, believed to be the sole pathogenic antigen in Heymann Nephritis, we conclude that failure to produce active or passive Heymann Nephritis in the dog using the same protocol that is successful in rats cannot be attributed to differences in antigenic make-up of the brush border membrane.

Animals↗
PubMed1986

Topical ibuprofen decreases thromboxane release from the endotoxin-stimulated burn wound.

A full-thickness burn wound in adult sheep releases prostanoids when they are injected locally with E. coli endotoxin, 2 micrograms/kg, resulting in an increase in pulmonary artery pressure (Ppa) from 20 +/- 3 to 34 +/- 5 mm Hg, and a decrease in mean arterial oxygen tension (PaO2) from 88 +/- 6 to 70 +/- 5 torr; this corresponds to an increase in venous plasma TxB2 content from a baseline of 220 +/- 79 pg/ml to 440 +/- 90 pg/ml. Burn prostanoid production, measured in lymph, increased ten- to fifteen-fold for both thromboxane A2, measured as TxB2, and prostacyclin, 6-keto-PGF1 alpha. The intravenous administration of ibuprofen, 12.5 mg/kg, eliminated both the increase in Ppa and decrease in PaO2 as well as the increase in burn lymph prostanoids. However, plasma prostanoids were also decreased below baseline, a potentially deleterious effect. A topical ibuprofen cream, 5% ibuprofen in a water-soluble ester, was applied to the burn hide every 6 hrs x 4 after which endotoxin was again injected below the hide. The pulmonary dysfunction was prevented as was the increase in plasma TxB2 with the value remaining at baseline. Burn lymph levels were only increased three- to five fold. Ibuprofen levels in burn lymph were maintained at 1-2 mcg/ml. The addition of the cream to the burn, however, did increase the wound bacterial content to 10(5)-10(7) bacteria/gram of tissue compared to 10(2)-10(3) for the dry, untreated burn, probably due to softening of the burn. Topically applied ibuprofen, therefore, can decrease burn wound prostanoid production from local endotoxin, preventing lung dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Muscle ammonia and amino acid metabolism during dynamic exercise in man.

The effect of dynamic exercise on muscle and blood ammonia (NH3) and amino acid contents has been investigated. Eight healthy men cycled at 50% and 97% of maximal oxygen uptake for 10 min and 5.2 min (to fatigue), respectively. Biopsies (quadriceps femoris muscle), arterial and femoral venous blood samples were obtained at rest and during exercise. Muscle NH3 at rest and after submaximal exercise was (means +/- SE) 0.5 +/- 0.1 mmol/kg dry muscle (d.m.) and increased to 4.1 +/- 0.5 mmol/kg d.m. at fatigue (P less than 0.001). The total adenine nucleotide (TAN) pool (TAN = ATP + ADP + AMP) did not change after submaximal exercise but decreased significantly at fatigue (P less than 0.001). The decrease in TAN was similar to the increase in NH3. Muscle lactate was 3 +/- 1 mmol/kg d.m. at rest and increased to 104 +/- 5 mmol/kg d.m. at fatigue. Whole blood and plasma NH3 did not change significantly during submaximal but both increased significantly during maximal exercise (P less than 0.001). During maximal exercise the leg released 7,120 mumol/min of lactate, whereas only 89 mumol/min of NH3 were released. NH3 accumulation in muscle could buffer only 3% of the hydrogen ions released from lactate, and NH3 release could account for only 1% of the net hydrogen ion transport out of the cell. Muscle glutamine was constant throughout the study, whereas glutamate decreased and alanine increased during exercise (P less than 0.001). No significant changes in either arterial whole blood glutamine or glutamate were observed. Arterial plasma glutamine and glutamate concentrations, however, increased and decreased (P less than 0.001), respectively, during exercise. It is concluded that (1) muscle and blood NH3 levels increase only during strenuous exercise and (2) NH3 accumulation is of minor importance for regulating acid-base balance in body fluids during exercise.

Adult↗
PubMed1986

Redox state changes in human skeletal muscle after isometric contraction.

Subjects maintained an isometric contraction of the quadriceps femoris muscle at two-thirds maximal voluntary contraction (m.v.c.) force for 5 s (5.0 +/- 0.3 s; mean +/- S.E. of mean; n = 6) or until fatigue (52 +/- 4 s; n = 13). Muscle biopsies were obtained at rest, immediately after the contractions and also at 1 and 4 min of recovery after contraction to fatigue. In all subjects 5 s isometric contraction resulted in an increase of muscle NADH (0.084 +/- 0.012 at rest to 0.203 +/- 0.041 mmol/kg dry wt.) and a decrease of phosphocreatine (PC; change in concentration = -17.3 +/- 3.8 mmol/kg dry wt.). Glucose-6-phosphate concentration was more than doubled whereas lactate increased in only four of the six subjects. The two subjects who did not show any increase in lactate also had the lowest increase in NADH. At fatigue NADH increased to 0.226 +/- 0.032 mmol/kg dry wt. which was not significantly different from the value after 5 s contraction. Muscle PC was nearly depleted and lactate increased 12-fold above resting levels. The major part (65%) of the NADH increase at fatigue had reverted after 1 min recovery but only a slight further decrease occurred between 1 and 4 min of recovery. In relative terms the time course of the changes in muscle NADH during the first minute of recovery was similar to that of PC resynthesis, suggesting a common regulator such as O2 availability. In contrast to the delayed return of NADH concentration, PC resynthesis continued during the later part of the recovery period and PC concentration was almost fully restored after 4 min of recovery. It is concluded that muscle NADH is already maximally increased in the first seconds of muscle contraction at two-thirds m.v.c. Indirect evidence indicates that this increase reflects a reduction of the mitochondrial NAD-NADH redox couple. The rapid establishment of a reduced mitochondrial redox state at the start of muscle contraction will probably lead to a reduction of the redox state in the cytoplasm also and therefore be important for enhancing lactate formation.

Adult↗
PubMed1986

Muscle ammonia metabolism during isometric contraction in humans.

The changes in ammonia (NH3) and amino acid contents in human skeletal muscle during isometric exercise (2/3 maximal voluntary contraction force) to fatigue have been investigated. Biopsies from musculus quadriceps femoris were obtained at rest, fatigue, and 1 and 4 min recovery. Muscle NH3 (n = 9) increased from 1.3 +/- 0.3 (mean +/- SE) mmol/kg dry muscle (dm) at rest to 3.6 +/- 0.6 at fatigue (P less than 0.01) and remained elevated during recovery, whereas the lactate increase after contraction decreased rapidly during recovery. Total adenine nucleotide (TAN) content decreased from 28.7 +/- 0.5 mmol/kg dm at rest to 25.1 +/- 0.6 at fatigue (P less than 0.001). Muscle glutamine did not change after contraction (P greater than 0.05), whereas glutamate decreased (P less than 0.001), and alanine increased (P less than 0.001). In vivo AMP deaminase activity (measured by the rate of TAN decrease) was positively correlated with the percentage of fast-twitch fibers (r = 0.92; P less than 0.001) and the ATP turnover rate (r = 0.75; P less than 0.001) but was not related to the muscle lactate content (r = 0.27; P greater than 0.05). Phosphocreatine decreased to 6.1 +/- 0.7 mmol/kg dm (range = 1-11) after contraction. It is concluded that during exercise activation of AMP deaminase in vivo occurs when a high ATP turnover rate is coupled with a low phosphocreatine level, muscle pH is of minor importance for direct activation of AMP deaminase in vivo, and increases in NH3 do not have an important influence on glycolysis.

AMP Deaminase↗
PubMed1986

Leg glucose uptake during maximal dynamic exercise in humans.

Leg glucose uptake (LGU) during submaximal (50% maximal O2 uptake) and maximal dynamic exercise (97%) has been quantified from the product of the leg blood flow and the arterial minus femoral venous glucose concentration. Muscle biopsies were also obtained. During 15 min of submaximal exercise the mean LGU values ranged from 1.07 to 1.25 mmol/min, which demonstrates that LGU was stable under this condition. In contrast, during maximal exercise LGU increased continuously, reaching 2.38 +/- 0.22, 2.95 +/- 0.32, and 3.82 +/- 0.34 mmol/min after 2, 4, and 5.2 min (fatigue), respectively. The mean LGU was negatively related to the mean muscle phosphocreatine content (r = -1.00;P less than 0.01). Intracellular glucose-6-phosphate (G-6-P) and glucose were very low at rest and did not change significantly during submaximal exercise (P greater than 0.05). However, at fatigue G-6-P and glucose increased substantially and were both 8.5 mmol/kg dry muscle (P less than 0.001). These findings demonstrate that during heavy exercise glucose accumulates in the cell probably due to hexokinase inhibition by G-6-P, and thus the rate of glucose utilization appears to be lower than the rate of glucose uptake. It is suggested that 1) LGU during short-term exercise is dependent on the energy state of the muscle and 2) LGU is equal to leg glucose utilization during submaximal exercise but is in excess of utilization during heavy exercise.

Adult↗
PubMed1986

Muscle ATP turnover rate during isometric contraction in humans.

ATP turnover and glycolytic rates during isometric contraction in humans have been investigated. Subjects contracted the knee extensor muscles at two-thirds maximal voluntary force to fatigue (mean +/- SE, 53 +/- 4 s). Biopsies were obtained before and after exercise and analyzed for high-energy phosphates and glycogenolytic-glycolytic intermediates. Total ATP turnover was 190 +/- 7 mmol/kg dry muscle, whereas the average turnover rate was 3.7 +/- 0.2 mmol . kg dry muscle-1 . S-1. The average ATP turnover rate was positively correlated with the percentage of fast-twitch fibers in the postexercise biopsy (r = 0.71; P less than 0.05) and negatively correlated with contraction duration to fatigue (r = -0.88; P less than 0.05). At fatigue, phosphocreatine ranged from 1 to 11 mmol/kg dry muscle (86-99% depletion of value at rest), whereas lactate ranged from 59 to 101. The mean glycolytic rate was 0.83 +/- 0.05 mmol . kg dry muscle-1 . S-1 and was positively correlated with the rate of glucose 6-phosphate accumulation (r = 0.83; P less than 0.05). It is concluded that a major determinant of the ATP turnover rate is the muscle fiber composition, which is probably explained by a higher turnover rate in fast-twitch fibers; fatigue is more closely related to a low phosphocreatine content than to a high lactate content; and the increase in prephosphofructokinase intermediates is important for stimulating glycolysis during contraction.

Adenosine Triphosphate↗