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Biomedical subjects

S Kaiser

Publications and source records attributed to S Kaiser.

At least 91 records · Page 5Linked to original sources
PubMed1990

Carotenoids, tocopherols and thiols as biological singlet molecular oxygen quenchers.

Singlet molecular oxygen (1O2) has been shown to be generated in biological systems and is capable of damaging proteins, lipids and DNA. The ability of some biological antioxidants to quench 1O2 was studied by using singlet oxygen generated by the thermodissociation of the endoperoxide of 3,3'-(1,4-naphthylidene) dipropionate (NDPO2). The carotenoid lycopene was the most efficient 1O2 quencher (kq + kr = 31 x 10(9) M-1 s-1). Tocopherols and thiols were less effective. The singlet oxygen quenching ability decreased in the following order: lycopene, gamma-carotene, astaxanthin, canthaxanthin, alpha-carotene, beta-carotene, bixin, zeaxanthin, lutein, bilirubin, biliverdin, tocopherols and thiols. However, the compounds with low quenching rate constants occur at higher levels in biological tissues. Thus, carotenoids and tocopherols may contribute almost equally to the protection of tissues against the deleterious effects of 1O2. The quenching abilities of carotenoids and tocopherols were mainly due to physical quenching. In case of some thiols chemical quenching also plays a significant role. Carotenoids and tocopherols have been reported to exert a protective action against some types of cancer.

Animals↗
PubMed1990

Genetic and molecular analysis of six tumor suppressor genes in Drosophila melanogaster.

Six Drosophila melanogaster tumor suppressor genes causing malignant or benign tumors in specific cell types are described. The wild-type alleles of these genes are instrumental in the differentiation of particular cell types. In the homozygous state, recessive mutations in the genes interrupt the differentiation of the cells and thus cause their uncontrolled, autonomous, lethal proliferation. The tumors show all major characteristics of malignant and benign neoplastic growth. Genomic sequences of four of the genes have been identified and are currently being characterized.

Animals↗
PubMed1989

Lycopene as the most efficient biological carotenoid singlet oxygen quencher.

Lycopene, a biologically occurring carotenoid, exhibits the highest physical quenching rate constant with singlet oxygen (kq = 31 X 10(9) M-1 s-1), and its plasma level is slightly higher than that of beta-carotene (kq = 14 X 10(9) M-1 s-1). This is of considerable general interest, since nutritional carotenoids, particularly beta-carotene, and other antioxidants such as alpha-tocopherol (kq = 0.3 X 10(9) M-1 s-1) have been implicated in the defense against prooxidant states; epidemiological evidence reveals that such compounds exert a protective action against certain types of cancer. Also, albumin-bound bilirubin is a known singlet oxygen quencher (kq = 3.2 X 10(9) M-1 s-1). Interestingly, those compounds with low kq values occur at higher plasma levels. When these differences are taken into account, the singlet oxygen quenching capacities of lycopene (0.7 microM in plasma), beta-carotene (0.5 microM in plasma), albumin-bound bilirubin (15 microM in plasma), and alpha-tocopherol (22 microM in plasma) are of comparable magnitude.

Bile Pigments↗
PubMed1989

Frequency measurements in real-time US equipment: variations from expected values.

The frequency responses of nine real-time mechanical probes and two pulsed Doppler probes from four manufacturers were measured. The reflected frequency was measured in a clinical environment by evaluating the pulser, transducer assembly, and receiver as a system. Two independent systems were used for these measurements: a spectrum analyzer and a data acquisition system that computed the fast Fourier transform of the reflected waveform. Results showed that probe frequency (calibrated by the manufacturer in the transmit mode with a hydrophone) was as much as 30% higher than that found by means of frequency measurement procedures with the probe attached to the ultrasound system and evaluated in the receive mode. Such large discrepancies indicate that if acceptance testing of the frequency spectrum is not performed at a clinical facility, prolonged clinical evaluation of new equipment should be arranged.

Ultrasonics↗
PubMed1988

Remote intramuscular injection of immobilising drugs into fish using a laser-aimed underwater dart gun.

Sixty coldwater and warmwater fish ranging in weight from 2 to 35 kg were injected intramuscularly with the hypnotics alphaxalone-alphadolone and metomidate hydrochloride and the non-depolarising muscle relaxant gallamine triethiodide using a laser-aimed underwater dart gun. Alphaxalone-alphadolone produced sufficient sedation for easy netting within five to 20 minutes at doses between 0.3 and 0.5 ml/kg, with induction being somewhat faster in warmwater species. The pattern of induction was similar with metomidate but required doses of 40 to 60 mg/kg. The muscle relaxant gallamine triethiodide showed promise as a practical agent for the capture and handling of large fish by virtue of its smooth induction of paralysis at doses between 1 and 3 mg/kg and its reversible supplementation with orally administered metomidate hydrochloride.

Anesthetics↗
PubMed1988

Ammonia and glutamine metabolism in human liver slices: new aspects on the pathogenesis of hyperammonaemia in chronic liver disease.

Ammonia and glutamine metabolism was studied in slices from normal, fatty and cirrhotic human livers. The liver disease was evaluated by histological examination. With respect to ammonia removal, urea and glutamine synthesis in human liver represent low and high affinity systems with k0.5(NH4+) values of 3.6 and 0.11 mM, respectively. Compared with normal control livers, cirrhotic livers showed a decreased glutamine synthesis from NH4Cl by about 80%. The same was true for urea synthesis. Conversely, flux through hepatic glutaminase was increased in cirrhosis 4-6-fold. These changes in hepatic glutamine and ammonia metabolism were observed regardless of whether reference was made to liver wet weight, DNA or protein content. Acetazolamide inhibited urea synthesis in cirrhotic liver slices by about 50%, indicating that mitochondrial carbonic anhydrase is required for urea synthesis also in cirrhosis. There was a significant correlation between the in-vitro determined capacity for urea synthesis from NH4Cl and the in-vivo determined plasma bicarbonate concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetazolamide↗
PubMed1987

Test-retest reliability of a standardized psychiatric interview (DIS/CIDI).

The reliability of DSM-III diagnoses using an expanded version of the Diagnostic Interview Schedule (DIS), called the Composite International Diagnostic Interview (CIDI), was evaluated by examining 60 psychiatric inpatients on a test-retest basis. Acceptable agreement coefficients of (kappa) 0.5 or above were found for all but two disorders: dysthymic disorder and generalized anxiety disorder. The subclassification of DSM-III affective disorders also revealed some discrepancies between the test and the retest interviews. When compared with results from earlier versions of the DIS, diagnostic reliability was found to have improved for the DSM-III anxiety disorders in particular. These improvements can possibly be attributed to some changes in the wording of the respective items of this section. Several reasons for lowered test-retest reliability are discussed.

Adult↗
PubMed1986

Liver carbonic anhydrase and urea synthesis. The effect of diuretics.

In isolated perfused rat liver, urea synthesis is rapid and reversibly inhibited not only by the well-known carbonic anhydrase inhibitors acetazolamide, methazolamide and ethoxzolamide, but also by diuretics, like xipamide, mefruside, chlortalidone, and chlorothiazide. Furosemide was without effect. Similar to findings with isolated perfused rat liver, acetazolamide inhibits urea synthesis from ammonium ions in normal and cirrhotic human liver slices. Inhibition of urea synthesis by xipamide and acetazolamide is accompanied by a 70% decrease of the cellular citrulline content and the tissue levels of 2-oxoglutarate and citrate, suggesting a block of urea synthesis at a step prior to citrulline formation. At a constant extracellular pH (7.4), inhibition of urea synthesis by xipamide, mefruside and acetazolamide was overcome by increasing the extracellular concentrations of HCO3- and CO2 to above twice the normal values. This shows that inhibition of urea synthesis by these diuretics is not due to an unspecific inhibition of one of the urea cycle enzymes but is due to an inhibition of mitochondrial carbonic anhydrase and therefore due to an impaired HCO3- provision for mitochondrial carbamoylphosphate synthesis. It is concluded that the activity of mitochondrial carbonic anhydrase is required for urea synthesis also in human liver and that several diuretics impair urea synthesis by inhibition of mitochondrial carbonic anhydrase. The pathophysiological significance of these data is discussed with respect to the development of diuretics-induced hyperammonemia and alkalosis in liver disease.

Acetazolamide↗
PubMed1985

Effect of dimethyl sulfoxide and glycerol on acute bowel ischemia in the rat.

After a 30 minute period of superior mesenteric artery occlusion in adult rats, there was a significant decrease in peritoneal inflammatory reaction, ileus, peritoneal adhesion formation, and histologically proved bowel wall necrosis in animals given intravenous dimethyl sulfoxide at the end of the ischemic period. In contrast, control rats given normal saline solution intravenously demonstrated severe inflammatory reaction, ileus, hemorrhagic peritoneal fluid, extensive adhesion formation, and areas of bowel wall necrosis. Intravenous glycerol did not have the beneficial effect seen with dimethyl sulfoxide. Neither compound was effective when given intraperitoneally. We conclude that intravenous dimethyl sulfoxide has a significant protective effect in rats with acute intestinal ischemia due to the superior mesenteric artery occlusion in the rat.

Animals↗
PubMed1983

Biochemical studies on structural and nonstructural proteins of the African green monkey B-lymphotropic papovavirus (LPV).

African green monkey (AGM) B-lymphotropic papovavirus (LPV) particles were separated from infected B-lymphoma BJA-B cells by neuraminidase and deoxycholate treatment and were further purified twice by CsCl density centrifugation. The SDS-PAGE analysis of virus particles banding at a density of 1.3510 g/ml and radioactively labeled by 125I revealed a major polypeptide of 40,000 and two minor polypeptides of 42,000 and 29,000. In addition, in infected BJA-B cells, all three viral structural polypeptides could be identified by immunoprecipitation. A nonstructural phosphopolypeptide of approximately 90,000 MW could be detected when sera against SDS-denatured SV40 T antigen or an AGM serum pool were used for immunoprecipitation. It is suggested that the 90K polypeptide of LPV represents an equivalent to T antigens of other papovaviruses.

Animals↗
PubMed1981

Infestivity of Psoroptes cuniculi in rabbits.

Starving Psoroptes cuniculi were found to survive off the host for 4 to 21 days at relative humidities between 20% and 99% and temperatures between 5 and 30 C. Within these extremes, survival was greatest at low temperature and high relative humidity (RH). Mites were infestive for at least 50% of their survival times and may have infested new hosts in contaminated facilities. A temperature of 40 C and 20% RH maintained for 24 hours caused 100% mortality in test mites. Other selected combinations of temperature above 40 C and RH less than or equal to 75% also caused 100% mortality in 2 days or less. These conditions could be used to control these mites in vacated contaminated premises.

Animals↗
PubMedDate not supplied

Effects of ACTH applications during pregnancy on the female offsprings' endocrine status and behavior in guinea pigs.

The present study was conducted to elucidate the effects of ACTH application during pregnancy on the female offsprings' endocrine status and behavior in a precocial animal, the guinea pig. We, therefore, studied daughters whose mothers were treated three times with either ACTH-depot or placebo during the sensitive phase of central nervous sexual differentiation of the foetus. From their 41st through their 80th day of age the spontaneous behavior of the daughters was recorded in their home cages, and concentrations of serum cortisol were determined from the 20th through the 90th day of age every 14 days. Daughters whose mothers had received ACTH displayed significantly lower amounts of a defensive aggressive behavior pattern, the urine spray, and they had higher cortisol concentrations than daughters whose mothers had received placebo. Thus, the number of species that shows consequences of an ACTH treatment during pregnancy for the offsprings' endocrine status and behavior is extended to include a precocial animal, the guinea pig.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Magnetic resonance measurements of the deviation of the angle of force generated by contraction of the quadriceps muscle in dogs with congenital patellar luxation.

OBJECTIVE: To measure the quadriceps angle (Q-angle) in dogs with congenital patellar luxation using magnetic resonance (MR) methods. STUDY DESIGN: Prospective clinical study. ANIMALS: Thirty-eight client-owned dogs. METHODS: Thirty-eight dogs were examined and placed into the following groups based on the degree of patellar instability: normal, grade I, grade II, and grade III. MR images of 37 pelvic limbs without patellar instability, 33 pelvic limbs with patellar luxation, and 6 limbs with cranial cruciate ligament (CrCL) rupture were made. The Q-angle was calculated using trigonometric methods based on MR images. Limbs with patellar luxation were compared with normal stifles and stifle with other disorders. RESULTS: The average Q-angle of the normal group was 10.5 degrees (24.9 degrees to -2.0 degrees ). The grade I group had an average Q-angle of 12.2 degrees (28.8 degrees to 2 degrees ), the grade II group 24.3 degrees (44.6 degrees to 7.7 degrees ), and the grade III group 36.6 degrees (51.4 degrees to 15.6 degrees ). The average Q-angle of limbs with an isolated CrCL rupture was 19.3 degrees (34.7 degrees to 3.9 degrees ). CONCLUSION: MR images can be used to make exact calculations of the Q-angle. CLINICAL RELEVANCE: MR images can be used to quantify the degree of patellar luxation.

Animals↗