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Biomedical subjects

S Thomas

Publications and source records attributed to S Thomas.

At least 595 records · Page 33Linked to original sources
PubMed1990

Superselective embolization using a coaxial catheter technique.

A method of superselective embolization of 0.64 mm or 0.89 mm coils using a coaxial catheter system is described. The normally functioning parts of an organ can be easily preserved. A number of clinical cases are briefly described which illustrate the application of this method. It is particularly suited to the control of bleeding points in diseased organs or precious organs such as transplants where embolization of a larger volume of tissue would have serious consequences.

Arteriovenous Fistula↗
PubMed1990

Miniplate osteosynthesis in cranial skeletal fixation.

The use of miniplate osteosynthesis provides a three-dimensionally stable form of fixation for cranial skeletal defects secondary to trauma or surgery. They are easily contoured and are thus able to support the bone fragments in the correct anatomical position. Miniplates of 0.9 mm thickness are sufficient to provide stable fixation without causing significant displacement of the overlying soft tissues. Plating thus provides excellent stability and cosmesis.

Adolescent↗
PubMed1990

[Laser lithotripsy with automatic shut-off on tissue contact].

A group of 88 patients with 89 ureteral calculi were treated with the pulsed dye-laser. Visual control was carried out through 8.5-F or 9.5-F ureteroscopes. The laser has automatic shut-off via spectrum analysis of back-scatter laser light. Effective laser pulses can therefore only be induced in the case of contact with the stone. Of the 89 stones 58 (65.2%) were completely fragmented by laser lithotripsy, 15 (16.8%) by laser lithotripsy in combination with ESWL and 9 (10.1%) by other ureteroscopic techniques. Ureterolithotomy was necessary only in 1 case (1%). There were 5 calculi (5.6%) that were too hard for fragmentation. The pulsed dye-laser is a safe and effective treatment modality for ureteral calculi that are not accessible for ESWL or in which ESWL has been unsuccessful. Further experimental and clinical trials will have to show whether miniature probes for electrohydraulic lithotripsy, dye-laser with automatic shut-off, or alexandrite laser will be the method of choice for lithotripsy of ureteral calculi.

Endoscopes↗
PubMed1990

Intestinal calcium transport in systemic disease. Studies with brush-border membrane vesicles.

Recent experiments utilizing brush-border membrane vesicles (BBMV) from small intestine to examine calcium uptake processes by the enterocyte are reviewed. Results demonstrate that (a) uptake must be examined in the time frame approaching initial rate, and (b) kinetics of saturable and nonsaturable processes be defined. Saturable uptake of calcium is carrier mediated, since it is inhibited competitively by strontium and noncompetitively by magnesium. Intravesicular strontium (but not magnesium), doubles Vmax for saturable uptake of calcium from the medium (countertransport), consistent with a mobile carrier. Since membrane lipid composition is expected to be an important determinant of function of a mobile carrier in a lipid bilayer, BBMV were treated with liposomes to change phospholipid and cholesterol content. Any change from native lipid composition decreased Vmax, but in treated BBMV, Vmax correlated with BBMV cholesterol content and fluidity. Since nonsaturable calcium uptake is extensively inhibited by both strontium and magnesium, electrostatic binding of calcium to the membrane is a major component of nonsaturable uptake. The remaining uninhibitable component of nonsaturable uptake is diffusion down the calcium concentration gradient. These concepts are applied to considering calcium uptake in disease and to the relationship of uptake to transenterocyte calcium movement.

Animals↗
PubMed1990

The bisphosphonate 2-PEBP inhibits cyclosporin A induced high-turnover osteopenia in the rat.

A bisphosphonate, 2-PEBP (2-(2-pyridinyl) ethylidene bisphosphonate), was administered to animals receiving cyclosporin A (CsA) in an attempt to modify the high-turnover osteopenia associated with CsA therapy. Four groups of female Sprague-Dawley rats were administered either vehicle or CsA (15 mg/kg per day) by gavage for 28 days, together with either normal saline solution or 2-PEBP (1.72 mg/kg per day) given by intraperitoneal injection on days 0,1, and 2. The groups thus comprised Group A, vehicle/normal saline; group B, vehicle/2-PEBP; group C, CsA/normal saline solution; group D, CsA/2-PEBP. All rats received tetracycline hydrochloride by intraperitoneal injection for histomorphometric labeling. Blood was sampled on days 0, 7, 14, 21, and 28 for ionized calcium, serum phosphate, parathyroid hormone (PTH), 1,25-dihydroxyvitamin D (1,25(OH)2D), blood urea nitrogen (BUN), creatinine, magnesium, and bone gla protein (BGP). Rats were killed on day 28 for tibial bone histomorphometry. All results were compared with group A. There were no significant differences in weight, ionized calcium, PTH, and serum phosphate between groups. Weight increased significantly by day 28 in all groups. Groups C and D revealed significantly higher levels of 1,25(OH)2D, BUN, and creatinine on days 14 and 28. Magnesium was significantly lower in groups C and D on days 14 and 28. BGP increased significantly in group C and decreased significantly in group B during the study. Tibial bone histomorphometry revealed high-turnover osteopenia in group C, significant improvement in both bone formation and resorption parameters in group D and hyperostosis in group B. Serum BGP reflected the histomorphometric indices of bone formation in each group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Serum hormone levels affect sperm function.

If hormone levels affect sperm motility during capacitation, then the serum added to samples prepared for artificial insemination could affect sperm fertilizability. We investigated various sperm functional movement characteristics (percent motile, progressive velocity, linearity, beat cross frequency, lateral head displacement, longevity, and hyperactivation) in specimens incubated with women's sera, as well as exogenous hormone preparations of estradiol (E2) and progesterone (P). Early follicular phase serum (low E2 and low P) maintained motility and longevity. Sperm in E2-treated medium exhibited higher progressive velocity, linear motility, and longevity. In contrast, the percent motility decreased as sperm exhibited hyperactivated motility with P.

Estradiol↗
PubMed1989

Use of silica gel polymer for DNA extraction with organic solvents.

Phenol and chloroform are the standard solvents used for DNA extraction. These solvents aid in the removal of protein and lipid from crude or partially purified cell extracts. Although the procedure is well established, the solvents are noxious, caustic, and unpleasant. We describe in this paper the use of a special blood collection tube to isolate the offensive organic solvents. With the use of silica gel polymer containing tubes, phenol, phenol:chloroform, or chloroform can be separated from the DNA containing aqueous phase in a rapid and safe manner. The method permits higher yields of DNA since the DNA is poured from the tube rather than aspirated with pipet.

Chemistry Techniques, Analytical↗
PubMed1989

Replicated item level factor structure of the MMPI: racial and sexual differences.

Item-level factor studies of the MMPI date back to the work of Comrey (1957). Surprisingly, there are no extant studies of the items that clinicians use most in the course of daily MMPI interpretive reporting, namely, the 399 x 399 matrix that represents all of the items that comprise the traditional clinical and validity scales. Furthermore, there are no prior studies with adequate Ns that have examined the replicability of MMPI factor structure via available factor comparison techniques (Harman, 1976). In this study, 20,000 MMPIs were factored by the principal components method, followed by Varimax rotations of 6 through 25 factors. The coefficient of congruence was used to compare the factor structures of randomly divided subsamples, as well as males vs. females and Blacks vs. Whites. Differences in factor structure were found, and suggestions are made with regard to the significance of these findings in clinical and applied settings.

Adult↗
PubMed1989

Cyclosporin A in the oophorectomized rat: unexpected severe bone resorption.

Local factors, such as interleukin-1, may mediate the accelerated bone remodeling in the acute estrogen-deficient rat. Cyclosporin A (CsA), which in vitro inhibits some of these local factors, was administered to oophorectomized (OX) rats in an attempt to modify this high turnover state. Three groups of 15 rats were studied. Group A was sham operated, group B was OX, and group C was OX and received CsA (15 mg/kg per day) by gavage commencing 4 days postoophorectomy for 28 days. Estradiol levels were determined to confirm oophorectomy. Blood was sampled on days -7, 0, 7, 14, 21, and 28 for ionized calcium (Ca2+), 1,25-(OH)2-vitamin D, PTH, and bone gla protein (BGP). Rats received tetracycline hydrochloride for bone histomorphometric labeling. All results were compared to group A. Body weight was increased in group B (p less than 0.003) but not in group C. There was no difference in Ca2+ or PTH between the groups. BGP levels were higher in group B by day 28 (p less than 0.005); BGP levels were increased in group C from days 7-28 (p less than 0.002). 1,25-(OH)2-vitamin D was significantly increased in group C (p less than 0.0001) but not in group B. Tibial bone histomorphometry revealed increased measurements of bone formation and osteoclast number without a loss of bone volume (BV/TV) in group B. Group C showed a dramatic increase in bone turnover with significant loss of BV/TV (p less than 0.001). In conclusion, CsA in the OX rat resulted in unexpected enhanced bone remodeling with high BGP levels and severe bone resorption.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Percutaneous transhepatic laser lithotripsy of gallstones--results of animal experiments].

Since laserinduced shock wave lithotripsy of gallstones is possible for treatment of common bile duct stones, the percutaneous transhepatic laserlithotripsy of stones in the gallbladder is examined in an animal study. In 8 animal experiments it could be shown that puncture of the gallbladder, dilatation of the working channel, (laserinduced) shock wave lithotripsy, removal of the fragments and the instruments are possible in one session. Neither when performing simple closure of the wound by suture nor by fibrinsealing severe side-effects could be recognized. After laserlithotripsy ablation of epithelium and hematomas can be observed, which are restituted within one month. The experiments show that in organ-saving shockwave lithotripsy there is no need for waiting for the development of a fistula and the percutaneous approach can be simplified.

Animals↗
PubMed1989

The c-myc oncogene is regulated independently of differentiation in myeloid cell lines.

Human myeloid leukaemia (U-937 and HL-60) cells when incubated at low cell densities with human recombinant gamma-interferon underwent functional maturation without any loss of proliferative potential relative to uninduced cells. In addition, the proportion of cells in S,G2/M and levels of c-myc oncogene (mRNA and protein) were maintained at the same level as those of untreated control cells. However, cells grown under similar conditions but with retinoic acid matured to the same extent but became growth inhibited with concomitant reductions in the proportion of cells in S,G2/M and levels of c-myc mRNA and protein. These studies indicate firstly that c-myc levels are regulated independently from differentiation in myeloid (non lymphoid) cells, secondly that gamma-interferon can induce differentiation without growth arrest under conditions of low cell density and thirdly emphasise the close association of c-myc expression with proliferative capacity.

Cell Cycle↗
PubMed1989

Angiosarcoma of the nasal cavity and maxillary antrum.

Angiosarcoma (malignant haemangioendothelioma) of the nasal cavity and paranasal sinuses is extremely rare. Only a few cases have been reported in literature. A case of angiosarcoma of the nasal cavity and maxillary antrum in a 38-year-old male patient is reported. He was treated with pre-operative external radiotherapy followed by wide excision of the tumour. He currently remains free of the disease 10 months after diagnosis (and seven months after completing therapy).

Adult↗
PubMed1989

Percutaneous transhepatic cholecysto-lithotripsy (PTCL).

Percutaneous transhepatic cholecystolithotripsy (PTCL) by laser or ultrasound is a minimally invasive form of treatment for gallstones. All the steps of the procedure can be performed in a single session. In clinical use severe side effects have not been observed.

Cholelithiasis↗