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Biomedical subjects

K Thomas

Publications and source records attributed to K Thomas.

At least 109 records · Page 6Linked to original sources
PubMed1999

Changing trend in susceptibility pattern of Streptococcus pneumoniae to penicillin in India.

Prior to 1995 all strains of Streptococcus pneumoniae isolated at a tertiary care hospital in south India were uniformly susceptible to penicillin. However, since late 1995 strains of S. pneumoniae with intermediate resistance to penicillin have been observed. Altogether there were 25 such isolates, 9 from invasive (5 from CSF as well as blood, 1 from pleural fluid and 3 from CSF alone) and 16 from noninvasive sites (6 from throat, 6 from sputum, 3 from eye and 1 from ear) respectively, thus 4.6 per cent of S. pneumoniae showed intermediate resistance of a total of 535 strains studied so far. The minimum inhibitory concentration (MIC) values of penicillin, erythromycin, chloramphenicol and cefotaxime were determined by agar dilution method and for confirmation, E test was carried out for penicillin alone. The MIC range obtained for penicillin was between 0.125-1.0 microgram/ml. Kirby-Bauer disc diffusion method was adopted for testing of erythromycin, chloramphenicol, co-trimoxazole, cefotaxime, tetracycline and vancomycin. We observed that none of the strains with intermediate resistance to penicillin were multidrug resistant. These strains belonged predominantly to serotype 14 (n = 10), 7B (n = 9), 19A (n = 3), 7F (n = 2) and 23F (n = 1). Clonality was not observed in the 5 representative strains subjected to Box A finger printing method.

Anti-Bacterial Agents↗
PubMed1998

Role of EP2 receptors and cAMP in prostaglandin E2 regulated expression of type I collagen alpha1, lysyl oxidase, and cyclooxygenase-1 genes in human embryo lung fibroblasts.

In a recent communication, we demonstrated that prostaglandin E2 (PGE2) lowers basal while it ablates interleukin-1beta((IL-1beta) and transforming growth factor-beta (TGFbeta) upregulated lysyl oxidase (LO) mRNA levels. Correspondingly, PGE2 increases cyclooxygenase-1 (COX1) mRNA in diploid, human embryo lung fibroblasts (IMR90) [Roy et al., 19961. We now report that these actions by PGE2 are routed through cAMP via the PGE2, EP2 receptor. Among the PGE2 receptor types, the IMR90 predominantly express the EP2 mRNA. These cells also express EP3 and EP4 mRNA at comparatively low levels. Northern blot analyses show that 11-deoxy PGE1, an EP2/EP4 agonist, emulates the action of PGE2. In a similar manner to PGE2, 11-deoxy PGE1 decreases basal and TGF-beta induced type I collagen alpha1 (COL) mRNA, basal and IL-1beta induced LO mRNA while it increases COX1 mRNA. Sulprostone, an EP3/EP1 agonist, has no effect on the expression of these three genes. Forskolin, an adenylate cyclase activator, acts in a very similar manner to PGE2 or 11-deoxy PGE1. It suppresses both basal and TGF-beta induced COL mRNA levels. Both PGE2 and 11-deoxy PGE1 increase cAMP to a level comparable with forskolin. The role of the EP2 receptor in controlling collagen production is further underscored in the immortalized Rat-1 fibroblasts, derived from Fischer rat embryos, which do not express detectable EP2 mRNA. In these cells, PGE2 has little effect on COL mRNA level, whereas forskolin increases it. Furthermore, forskolin increases cAMP level in Rat-1 cells, whereas PGE2 does not. Overall, these results illustrate that much of the PGE2 action on the expression of COL, LO, and COX1 genes is mediated through the EP2 receptor and a subsequent increase in intracellular cAMP.

Alprostadil↗
PubMed1998

Oxygen induces fatty acid (n-6)-desaturation independently of temperature in Acanthamoeba castellanii.

Induction of a microsomal oleate delta12 (n-6) desaturase which is mainly responsible for an increase in membrane lipid unsaturation at low temperature has been observed in the free-living amoeba Acanthamoeba castellanii. In this study we show that the enzyme can also be regulated by oxygen independently of temperature in batch cultures grown to O2-limitation. Raising the oxygen concentration from below the lower limit of detection (< 0.1 microM) to approximately air-saturation (230 microM), whilst maintaining the growth temperature constant (30 degrees C), increased lipid unsaturation and elevated n-6-desaturase activity 2.3-fold. Addition of the protein synthesis inhibitor, anisomycin, showed that increased desaturase activity was due to new protein synthesis rather than activation of pre-existing enzyme. These observations are important for future studies of the mechanism of temperature adaptation in poikilotherms.

Acanthamoeba↗
PubMed1998

Analysis of domoic acid in shellfish by thin-layer chromatography.

A thin-layer chromatography (TLC) method has been developed for the semi-quantitative analysis of domoic acid (DA) in shellfish tissues. Tissues were extracted in a single-step homogenization of tissue with 50 % aqueous methanol and then taken through a selective strong anion exchange cleanup. Cleaned extracts were applied directly to silica gel TLC plates and developed with a butanol-acetic acid-water mixture (3:1:1, Rf = 0.45 for DA). As little as 10 microg DA per gram of tissue could be detected after chromatography using a hand-held short-wave UV lamp to detect fluorescence quenching. Confirmation was provided by spraying the plate with ninhydrin, which reacts with the secondary amine of DA to give a distinctive yellow colored product. The extraction, cleanup and TLC procedures are fast and simple, and do not require the use of expensive equipment. This method should prove useful for the routine screening of shellfish tissues in those laboratories not equipped with an LC system. It should also be useful as a chemical confirmation method for DA in samples tested positive by assay methods such as immunoassay.

Animals↗
PubMed1998

Uniform discrimination of pattern orientation by honeybees.

To explore how honeybees, Apis cerana, discriminate the orientation of patterns, we trained workers to discriminate between a black stripe of a certain orientation on a white disc and a pure white disc. We tested trained bees for their ability to discriminate between the trained orientation and deviations from it. This was done either in a dual choice situation where the bees had to choose between the trained orientation and one deviation from it at a time, or in a multiple choice situation where bees had to choose simultaneously between the trained orientation and 11 successive deviations from it. In the dual choice situation, bees did not discriminate behaviourally between the trained orientation and deviations up to 25 degrees, whereas in a multiple choice situation, they discriminated between the trained orientation and a deviation of 15 degrees or more. Thus, orientation can be analysed more precisely in multiple choice experiments. The response of the bees was independent of the orientation of the trained orientation; the 12 different trained orientations all yielded identical results. This finding, considered together with a model that we present for orientation discrimination, suggests that at least three orientation-sensitive channels (a neuron or a set of neurons that respond maximally to a particular orientation) participate in the analysis of pattern orientation. (c) 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Renal cell carcinoma containing fat mimicking angiomyolipoma: demonstration with CT scan and histopathology.

We report a case of a large renal tumour containing small amounts of fat and some calcification that proved to be a renal cell carcinoma. The CT appearance of the tumour was suggestive of an angiomyolipoma. Although the overwhelming majority of renal masses containing fat are angiomyolipomas, in the presence of calcification the diagnosis of renal cell carcinoma should be entertained.

Adipose Tissue↗
PubMed1998

Advance in the study of inhibin, activin and follistatin production in pregnant women.

This review summarizes the new information on the studies of inhibin, activin, and follistatin production in the placenta during human pregnancy. Inhibin and activin exert suppressive and stimulatory effects, respectively, on the release of FSH in the pituitary. Follistatin is bound to inhibin and activin and indirectly modulates the FSH release. The placenta produces these three proteins. The serum levels of inhibin, activin, and follistatin are elevated in pregnant women and decrease after delivery. The trophoblast cells from term placenta secrete inhibin and activin in the primary cultures. The production and mRNA expression of inhibin and activin are regulated by several stimulatory and suppressive hormones and growth factors in placental tissues. cAMP, Ca2+, and protein kinase-C may be involved in intracellular signal transduction in trophoblasts. Activin receptors are present on placental cells. Follistatin inhibits the binding of activin to ActRII receptor. Abnormal levels of inhibin and activin in maternal serum are observed in problem pregnancies and gestational diseases. Inhibin, activin, and follistatin may play roles in the regulation of reproductive endocrinology in pregnant women and the embryo/fetal development.

Activin Receptors↗
PubMed1998

Deriving a preference-based single index from the UK SF-36 Health Survey.

This article presents the results of a study to derive a preference-based single index from the SF-36. The study was an attempt to reconcile a profile health status measure, the SF-36, with the "quality adjusted life years" approach. The study undertook a parsimonious restructuring of the SF-36 using explicit criteria to form the SF-6D health state classification. A sample of multidimensional health states defined by this classification were valued by a convenience sample of health professionals, managers, and patients, who responded to a set of visual analogue scale ratings and standard gamble questions, with highly complete and consistent answers. Statistical models were estimated to predict single index scores for all 9000 health states defined by the new classification. The resultant algorithms can be applied to existing SF-36 data sets and used in the assessment of the cost-effectiveness of health technologies. This preliminary work forms the basis of a larger study currently being undertaken in the UK.

Algorithms↗
PubMed1998

Glucose concentration in human subcutaneous adipose tissue: comparison between forearm and abdomen.

There is still controversy about the relation between the glucose concentration in the subcutaneous (sc.) adipose tissue and the blood plasma. Depending on the technique applied, the glucose concentration in sc. tissue varies between 50% and 100% of the plasma glucose concentration. In the present study the sc. glucose concentration of forearm and abdomen in seven healthy volunteers was compared with plasma glucose by applying the microdialysis technique with very low flow rates. A microdialysis probe implanted into the subcutaneous tissue of abdomen and forearm was perfused with a flow rate of 1 microl/4 min. The dialysate was sampled in three 2-h-fractions in the fasting state and in one 2-h-fraction during a hyperglycemic clamp (216.9+/-3.4 mg/dl) (mean +/- SEM). The mean recoveries of the plasma glucose were 91.1+/-4.1% in the forearm and 82.7+/-18.0% in the abdomen. The recoveries in the sc. tissue of abdomen and arm were not significantly different. However, the arm showed significantly (p < 0.014) less interindividual variance (range 73.2- 103.2%) than the abdomen (range 50.6-117.1%) and appears to be the preferable implantation site. The recovery remained constant during the investigation.

Abdomen↗
PubMed1998

Joint stiffness and 'articular gelling': inhibition of the fusion of articular surfaces by surfactant.

It was proposed some years ago that, in osteoarthritis, one source of joint stiffness arises from 'articular gelling', but, if so, why does this not occur in the normal joint? In a preliminary experiment using agar gels, it is shown how such fusion of gel surfaces can be inhibited by surface-active phospholipid (SAPL)--both synthetic and human--as quantified by the shear stress needed to cause cleavage between samples after prolonged contact. On the other hand, normal bovine articular cartilage (BAC) does not fuse to itself, but can be made to do so if rinsed with a powerful lipid solvent known to remove the outermost layer of adsorbed SAPL along with the hydrophobicity so characteristic of the normal 'waxy' surface it imparts. It is then shown how the inhibition of gel fusion can be restored by treating both bovine and human articular surfaces with exogenous SAPL derived from human AC and with synthetic SAPL. Samples of human articular cartilage excised from osteoarthritic hips and knees during total joint replacement showed a 55% greater tendency to fuse together than normal BAC. This was exacerbated by solvent rinsing and can be attributed to a deficiency in the outermost lining of SAPL previously studied as a load-bearing boundary lubricant capable of reducing friction and wear to the remarkably low levels observed physiologically. Hence, joint stiffness can be attributed, in part, to a deficiency in the lubricating layer of SAPL lining the normal articular surface where it can inhibit articular gelling/gel fusion, possibly imparting other desirable physiological functions. The possibility of clinical replenishment of SAPL in the osteoarthritic joint is discussed.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1998

Cerebral fungal infections in the immunocompromised host: a literature review and a new pathogen--Chaetomium atrobrunneum: case report.

OBJECTIVE AND IMPORTANCE: A case of a cerebral abscess, occurring in a patient who had undergone bone marrow transplant, caused by a new pathogen, Chaetomium atrobrunneum, and a review of the literature are presented. Although Aspergillus species are by far the most common fungi found in cerebral abscesses in immunocompromised patients, an increasing number of fungi commonly found in nature but not usually associated with infections in humans have been isolated from cerebral abscesses in these patients. CLINICAL PRESENTATION: A 31-year-old male patient, who had undergone a recent bone marrow transplantation for multiple myeloma, presented 3 months after transplantation with right-sided hemiplegia caused by a left parietal hemorrhagic lesion. INTERVENTION: A biopsy guided by computed tomography showed that the abscess contained the fungus C. atrobrunneum. The final identification of the organism was based on cultures, scanning electron microscopic studies, and consultation with the Fungus Testing Laboratory at the University of Texas Health Science Center, San Antonio, TX. The patient was treated with several antifungal medications but developed uncontrolled cerebral edema, which led to further neurological deterioration and eventual death. CONCLUSION: Cerebral abscesses in the immunocompromised patient may no longer be assumed to be caused solely by Aspergillus species. The literature reveals several rare cases of uncommon fungi found in these abscesses. Only four cases of cerebral infections caused by the genus Chaetomium have been reported. The case presented represents the first time a patient who had undergone a bone marrow transplant with a cerebral abscess was found to be caused by the pathogen C. atrobrunneum.

Adult↗
PubMed1998

Correlation of gallbladder ejection fraction with pathologic grade for chronic inflammation.

BACKGROUND: The purpose of this study is to define the sensitivity and specificity of the gallbladder ejection fraction (GBEF) for identifying patients with various grades of histologically proven chronic cholecystitis. METHODS: Of 693 consecutive patients who had a scintigraphic GBEF determination at Baptist Medical Center of Oklahoma, 161 subsequently had a cholecystectomy at the same institution. Pathologic material was reassessed by one outside blinded reviewer, who graded the intensity of the inflammation present on a 0 (absent) to 3 (most severe) scale. RESULTS: The least square mean maximum GBEF was 23.7% for those with grade 0, 9.6% for those with grade 3, and 13.9% for those with cholesterolosis. If a normal value for GBEF is set at > 30%, the sensitivity for detecting grade 1, 2, or 3 disease was 84%, and the specificity was 26%. For grade 3 disease alone, the sensitivity was 100%, and the specificity was 26%. CONCLUSIONS: The GBEF is sensitive but not specific for chronic inflammation of the gallbladder. The GBEF appears to be useful as a screening examination in the appropriate clinical setting.

Cholecystitis↗
PubMed1998

PCR-Enzyme immunoassay for detection of Streptococcus pneumoniae DNA in cerebrospinal fluid samples from patients with culture-negative meningitis.

A PCR-based assay was developed to amplify a conserved region of the pneumococcal autolysin gene. The amplified product was labelled with digoxigenin-labelled dUTP and was detected with a biotin-labelled probe in an enzyme immunoassay (EIA). The assay was initially tested with suspensions of various serotypes of Streptococcus pneumoniae and other gram-positive and gram-negative bacteria and was then applied to cerebrospinal fluid (CSF) specimens from patients with meningitis and those with other neurological disorders. The assay detected all the serotypes of S. pneumoniae tested, whereas all the other bacterial strains tested were negative. Seven of the 8 CSF specimens positive for pneumococcus by culture or latex agglutination (LA) were positive by PCR-EIA, whereas all 10 specimens positive for other organisms were negative. Among 11 patients with clinically diagnosed meningitis but with negative culture and LA results, 5 were positive by PCR-EIA. The assay was negative for all but one patient without meningitis; it was positive with the CSF from a child with immunodeficiency and pneumococcal abscesses on the scalp. PCR-EIA is a useful tool for the diagnosis of meningitis, especially when culture and LA are negative because of prior antibiotic treatment.

Child↗
PubMed1998

Hybrid capture II, a new sensitive test for human papillomavirus detection. Comparison with hybrid capture I and PCR results in cervical lesions.

AIM: To test a new assay for the detection of human papillomavirus (HPV) DNA, hybrid capture II (HC II), compared with the previous commercialized hybrid capture I (HC I) and polymerase chain reaction (PCR) results on cervical scrapes from fresh cone excision biopsy samples. METHODS: The three methods were used on cervical scrapes from 42 fresh cone excision biopsy samples. There were nine metaplastic and inflammatory lesions, five low grade lesions, and 28 high grade lesions. PCR was performed using the general primers GP5+/GP6+. The viral load of high risk HPV DNA was estimated by the ratio of relative light units to positive control values in the samples. RESULTS: The sensitivity of HC I for the detection of high grade lesions was 71.4%, while it was 92.8% for HC II and 96.4% for the PCR. Considering only the absence of detectable cervical in situ neoplasia, the specificity was 88.9% for HC I, 66.7% for HC II, and 66.7% for PCR. With HC II, for a ratio of cervical sample to normal control of > 200, the sensitivity for the detection of high grade lesion was only 34.6% with a specificity of 66.7%. CONCLUSIONS: HPV detection with the HC II assay is more sensitive than the previous HC I and represents a more convenient and easier test than PCR for routine use. Nevertheless the viral load estimated with this test cannot be a reliable predictive indicator of high grade lesions.

Cervix Uteri↗