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Biomedical subjects

M Gomez

Publications and source records attributed to M Gomez.

At least 19 recordsLinked to original sources
PubMed1992

Occupational risk factors for multiple myeloma among Danish men.

A large population-based case-control study evaluated occupational exposures in 1,098 Danish males diagnosed with multiple myeloma from 1970 to 1984 and in 4,169 age- and gender-matched controls alive at the time of case-diagnosis. Industrial histories were obtained from the Supplementary Pension Fund which, since 1964, has recorded employments of adult Danes; occupation came from subjects' most recent tax records. Four industrial hygienists created a job-exposure matrix for 47 substances based on 15,000 unique industry/occupation combinations in subjects' histories. Risk of myeloma was significantly elevated among road and railroad workers, precision metalworkers, and workers in the transportation and communication industries. Risk increased significantly with duration of employment in: production of synthetic yarns, plastic packaging, and miscellaneous chemical compounds; fabricating structural metal and stationary tanks; body factories; electrical plants; and retail sale of paint and wallpaper. Risks of myeloma were elevated, though statistically nonsignificantly, in all categories of exposure to gasoline and engine exhausts. Risks rose with likelihood and duration of exposure to phthalates, and were statistically significant and nearly fivefold with probable exposure to vinyl chloride for five or more years. After adjusting for multiple exposures and disregarding exposures within 10 years of diagnosis (or selection as a control), probable exposure to vinyl chloride was associated with increased risk of myeloma, which rose to fivefold with longer exposure. Associations with gasoline, engine exhausts, and phthalates persisted, but were inconsistent with duration and probability of exposure. Previously reported associations with agriculture were not confirmed by these data.

Age Factors↗
PubMed1992

Changes in the susceptibility of Bacteroides fragilis group organisms to various antimicrobial agents 1979-1989.

The in vitro activity of metronidazole, chloramphenicol, clindamycin and 11 beta-lactam antibiotics against 135 clinical isolates of the Bacteroides fragilis group was compared. In addition, changes in the resistance patterns of members of the Bacteroides fragilis group isolated at the Hospital Universitario San Carlos in Madrid, Spain, between 1979 and 1989 were documented. The most active beta-lactam drugs were imipenem and beta-lactamase inhibitor combinations. In 1989, however, two strains were found to be resistant to imipenem and to all other beta-lactam agents tested. There was no emergence of resistance to metronidazole. Chloramphenicol was very effective: only one resistant strain was detected in 1979 and no chloramphenicol-resistant isolates were found during the rest of the study period. An outbreak of clindamycin resistance was noted in 1982, and the first cefoxitin resistant strains were recovered in 1985. The changing patterns of susceptibility of anaerobic bacteria to antimicrobial agents and the emergence of Bacteroides fragilis strains resistant to new beta-lactam agents suggest that periodic antimicrobial susceptibility tests should be performed in order to guide the selection of antimicrobial agents for therapy.

Anti-Bacterial Agents↗
PubMed1992

Tiron administration minimizes the toxicity of vanadate but not its insulin mimetic properties in diabetic rats.

Although it has been reported that vanadate is effective in diminishing the expression of diabetes in the rat, the severe toxic side effects noted in the vanadate-treated animals suggest that chronic oral administration of vanadate argues against its use in human diabetes. The present study was conducted to evaluate the effects of the chelator Tiron on the mobilization of vanadium after administration of sodium metavanadate in the drinking water (0.20 mg/ml) of streptozotocin-induced diabetic rats for 35 days. Intraperitoneal treatment with Tiron (300 or 600 mg/kg) was initiated after three weeks of vanadate administration and continued for two weeks. The ameliorative effects of vanadium with respect to diabetes were not diminished by the administration of Tiron, but the accumulation of vanadium in kidney and bone was significantly decreased in the Tiron-treated groups and diabetes associated increases in serum GOT, GPT and cholesterol were diminished with Tiron treatment. It is concluded that the coadministration of metavanadate and Tiron may be of potential value for treatment of diabetes mellitus.

1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗
PubMed1992

Electrophysiological recordings in solitary photoreceptors from the retina of squid, Loligo pealei.

A protocol was developed to isolate enzymatically photoreceptors from the retina of the squid, Loligo pealei. The procedure routinely results in a high yield of intact cells. Examination of solitary photoreceptors under Nomarski optics revealed that the fine morphological features described in anatomical studies of retinal sections are retained. The distal segment is up to 250 microns long, 4-7 microns wide, covered in part by short microvilli; the inner segment and the cell body, with the initial portion of the axon, are also clearly discernible in solitary cells. Suction electrode measurements performed from the cell body confirmed that responsiveness to light survived cell isolation. Macroscopic membrane currents were measured using the whole-cell tight-seal technique, and the perforated-patch method. Step depolarizations of membrane voltage administered in the dark elicited a slowly activating, sustained outward current. Light stimulation evoked an inward current graded with stimulus intensity; the peak current could amply exceed 1000 pA. Intense photostimulation gave rise to a prolonged inward aftercurrent that lasted for tens of seconds. On-cell patch recording along the intermediate segment and most of the smooth areas of the distal segment showed a large incidence of silent patches, with the occasional presence of voltage-dependent channels. On the other hand, channel activity could be recorded more frequently from electrode placements near the apical tip of the cell, where the presence of microvilli could be confirmed visually. Some patches were unresponsive to voltage stimulation applied in the dark but produced distinct bursts of channel openings after illumination. The feasibility of single-cell electrophysiology in isolated photoreceptors, together with the growing body of biochemical information on cephalopod preparations, makes squid an attractive model system to investigate the visual process in invertebrates using multiple experimental approaches.

Animals↗
PubMed1992

Expression of syndecan in transformed mouse keratinocytes.

BACKGROUND: Malignant transformation is frequently associated with altered behavior of cells, a phenomenon that also suggests changes in cell-matrix interactions. We have studied expression of syndecan, a cell surface proteoglycan that binds extracellular matrix components and growth factors, in various chemically transformed mouse keratinocyte cell lines that differ in their morphology and tumorigenicity. EXPERIMENTAL DESIGN: A monoclonal antibody, specific for mouse syndecan, and a cDNA clone for mouse syndecan, were used to detect syndecan in seven different keratinocyte cell lines. The glycosaminoglycan composition of syndecan was studied using differential digestions of heparan sulfate and chondroitin sulfate chains. RESULTS: In general, the tumorigenic cells were found to express lower amounts of syndecan, both at protein and mRNA levels, than the nontumorigenic cells. The most tumorigenic cell line CarC revealed barely detectable syndecan expression. Also, molecular polymorphism of syndecan was observed, as three forms of syndecan with different molecular weights appeared on the surfaces of different keratinocytes. The highly tumorigenic cells, that expressed low amounts of syndecan, expressed syndecan with the largest molecular weight. The different molecular weights were shown to reflect an increased amount of both heparan and chondroitin sulfate chains attached to the core protein. An increased shedding of syndecan ectodomain from the membrane-associated domain was observed in cells that express high amounts of mutated Ha-ras p21. CONCLUSIONS: The results suggest, that transformed epithelial cells can modulate the appearance of syndecan on the cell-surface by at least two ways: (a) by altering its glycosylation or (b) by increasing its shedding from the cell surface. These modulations, together with overall suppression of syndecan expression, could be associated with malignant transformation of keratinocytes.

Animals↗
PubMed1992

Administration of vanadyl sulfate by gavage does not normalize blood glucose levels in streptozotocin-induced diabetic rats.

Vanadyl sulfate trihydrate was given by gavage to streptozotocin-induced diabetic rats for 21 days at doses of 0, 25, 50, or 75 mg/kg/day. In marked contrast to the reduction in plasma glucose observed in diabetic animals given vanadyl sulfate via drinking water, diabetic rats given vanadyl by gavage were not characterized by normoglycemia. Similarly, in contrast to the normalizing effect of vanadyl in drinking water, vanadyl by gavage had only a minimal influence on diabetes associated hyperphagia and polydipsia. Despite the lack of marked effect of vanadyl by gavage on the above parameters, tissue vanadium accumulation in the gavaged rats was similar to that reported for rats given vanadium by drinking water. The present results (taken together with previous data) show that the administration of vanadium by gavage is not a viable alternative to the use of insulin in diabetes treatment.

Animals↗
PubMed1992

Evaluation of ground ambulance, rotor-wing, and fixed-wing aircraft services.

It is hoped that this article has offered insightful suggestions and criteria in choosing the most appropriate method to transport patients. Ground ambulances, rotor-wing, and fixed-wing aircraft each have advantages and disadvantages in particular circumstances. The advantages and disadvantages of any mode of transport must be considered to best meet the needs of the patient. In the twentieth century alone, great strides have been made in the field of emergency stabilization and transport. An efficient, well-trained ground ambulance program remains the backbone of prehospital and interhospital transport systems. Helicopters and fixed-wing transports must be integrated into the EMS system. One advantage of the helicopter and fixed-wing aircraft is rapid travel times when time is critical. As Hicks et al said, "early resuscitation and timely transfer of selected patients are critical factors in reducing morbidity and mortality." The future holds many possibilities for enhanced patient transport. Hospitals may be able to use tilt-rotor, vertical landing, fixed-wing aircraft to combine the advantages of helicopter and fixed-wing aircraft. After all, our primary goal is to get the right patient, with the right personnel, to the right place in the right amount of time.

Aircraft↗
PubMed1991

Oral vanadium administration to streptozotocin-diabetic rats has marked negative side-effects which are independent of the form of vanadium used.

In the present investigation, the effects of oral administration of sodium metavanadate, sodium orthovanadate and vanadyl sulphate to alleviate some signs of diabetes in streptozotocin-treated rats have been evaluated. Streptozotocin-induced diabetic rats drank aqueous solutions (NaCl, 80 mM) containing sodium metavanadate (0.15 mg/ml), sodium orthovanadate (0.23 mg/ml), or vanadyl sulphate pentahydrate (0.31 mg/ml) for 28 days. The vanadium-treated animals were compared to controls, either diabetic or nondiabetic, receiving drinking water containing NaCl (80 mM) only. Daily food and fluid intake were significantly decreased in the vanadium-treated animals relative to diabetic controls. Also, vanadium treatment reduced the level of hyperglycemia in diabetic rats, with sodium metavanadate being the most effective of the vanadium compounds tested. However, daily vanadium intake was significantly lower in the animals receiving sodium metavanadate. Signs of toxicity were observed in all vanadium-treated animals as evidenced by some deaths, decreased weight gain, and increased serum concentrations of urea and creatinine. Moreover, vanadium was detected in all tissues analyzed. Although some signs of diabetes were improved by vanadium treatment, because of the severe toxic side effects noted in all of the vanadium-treated animals, it seems evident that oral vanadium administration is not a suitable therapy of diabetes mellitus in streptozotocin-diabetic rats.

Administration, Oral↗
PubMed1991

Evaluation of the efficacy of various chelating agents on urinary excretion and tissue distribution of vanadium in rats.

The effect of repeated intraperitoneal administration of Tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid), ascorbic acid, deferoxamine (DFOA) or 2-mercaptosuccinic acid on urinary excretion and tissue distribution of vanadium was assessed in rats which had previously received 12 intraperitoneal injections of sodium metavanadate (1.84 mg/kg per injection) or vanadyl sulphate trihydrate (6.35 mg/kg per injection) during a 4-week period. Chelating agents were administered daily for 5 days at doses equal to one-eighth of their respective LDSO. Only Tiron significantly decreased the tissue concentration of vanadium, whereas DFOA and Tiron significantly enhanced the urinary excretion of vanadium after repeated parenteral administration of sodium metavanadate. Again, only Tiron significantly increased the urinary elimination of vanadium following vanadyl sulphate administration. The results of this study show that Tiron has potential beneficial effects in the treatment of repeated intraperitoneal vanadium poisoning, while the effectiveness of DFOA is very uncertain. 2-Mercaptosuccinic and ascorbic acids were not effective as antidotes for parenteral vanadium intoxication.

Animals↗
PubMed1991

Influence of some dietary constituents on aluminum absorption and retention in rats.

Eight groups of female Sprague-Dawley rats were treated with 281 mg Al(OH)3/kg/day by gastric intubation five times a week for five weeks. Concurrently, animals in seven groups received ascorbic acid (56.3 mg/kg/day), citric acid (62 mg/kg/day), gluconic acid (62.7 mg/kg/day), lactic acid (28.8 mg/kg/day), malic acid (42.9 mg/kg/day), oxalic acid (28.8 mg/kg/day), and tartaric acid (48 mg/kg/day) in the drinking water. The eighth group did not receive any dietary constituent in the water and was designated as the control group. Animals were placed in plastic metabolic cages and urine was collected during the treatment period. The liver, spleen, kidney, brain and bone aluminum levels of each rat were measured, as well as the total amount of aluminum excreted into urine. All the dietary constituents significantly increased the aluminum concentrations in most of the tissues, with ascorbic and citric acids showing the highest rate of aluminum accumulation. In contrast, no significant differences between control and treated rats were observed in the concentrations of aluminum excreted into urine. In view of these results, we suggest that the effects of the simultaneous ingestion of aluminum hydroxide and those dietary constituents in uremic animals should be evaluated. Meanwhile, the diet of uremic patients should be carefully monitored.

Acids↗
PubMed1990

Chelating agents in the treatment of acute vanadyl sulphate intoxication in mice.

Eighteen chelating or reducing agents were tested to determine their relative efficacy as antagonists in acute intramuscular vanadyl sulphate intoxication in mice. The chelating or reducing agents were administered intraperitoneally to male Swiss mice at doses equal to one-fourth of their respective LD50. Therapeutic effectiveness (TEF) was calculated. In a subsequent experiment, the effect of EDTA, glutathione, DFOA, ascorbic acid, succinic acid, monosodium phosphate, Tiron, DTPA, and 2-mercaptosuccinic acid on the excretion, and distribution of vanadium was determined. Of the compounds examined, Tiron followed by ascorbic acid, and 2-mercaptosuccinic acid were effective in increasing the urinary excretion of vanadium. Tiron, and 2-mercaptosuccinic acid were also effective in reducing the concentration of vanadium found in kidney, the main target organ of vanadium accumulation. Tiron appears to be the most effective agent of those tested in the prevention of acute vanadium (IV) intoxication in mice.

Animals↗
PubMed1990

Occupation and risk for testicular cancer: a case-control study.

A case-control study of 271 testicular cancer cases aged 18-42, including 60 seminomas and 206 other germinal cell tumours, and 259 controls was carried out to study the association between occupation and testicular cancer risk. Study subjects were identified at three medical centres, two of which treat military personnel. Controls were men diagnosed with a cancer other than of the genital tract. Associations were identified between professional employment (administrators, teachers and other professionals) and risk for testicular seminoma, OR = 2.8 (95% Cl: 1.4-5.4) and between employment in production work and risk for other germinal cell tumours, OR = 1.8 (95% Cl: 1.1-2.7). No specific occupations within these broad groups were responsible for observed increases. Self-reported exposure to microwave and other radio waves was associated with an excess risk for both seminomas and other germinal cell tumours. However, an assessment of radio wave exposure based on job title did not support this finding. Although testicular cancer has been increasing in recent decades among young males, occupational factors did not appear to account for a substantial proportion of testicular cancer occurrence in the population studied.

Adolescent↗
PubMed1990

Comparative study of 5% permethrin cream and 1% lindane lotion for the treatment of scabies.

A multicenter, randomized, investigator-blind controlled trial was conducted to compare the safety and efficacy of a single, whole-body application of 5% permethrin cream with that of 1% lindane lotion for the treatment of scabies in 467 patients. At 14 +/- 3 days after treatment, the mean active lesion count decreased from pretreatment levels of 85 (range, 4 to 600) in both treatment groups to 14 (range, 0 to 133) in the permethrin group and to 15 lesions (range, 0 to 500) in the lindane group. At 28 +/- 7 days after treatment, complete resolution had occurred in 181 (91%) of 199 patients treated with permethrin and in 176 (86%) of 205 patients given lindane. Pruritus due to scabies persisted at 28 +/- 7 days in 14% of the permethrin group and in 25% of the lindane group. The most frequent adverse effects were new or increased pruritus and mild, transient burning or stinging; the latter was slightly more frequent following permethrin treatment and appeared to be related to severity of infestation. Because of a lower potential for neurologic toxicity, permethrin may be preferable to lindane for the treatment of scabies particularly in children.

Adolescent↗
PubMed1990

Benign osteoblastoma of vertebral column and skull. Report of two cases.

Osteoblastoma of the spine is a rare but important cause of back pain and the sciatica syndrome in young adults. Osteoblastoma of the skull is rare and the involvement of the orbital roof is very unusual. Clinical complaints and physical examination are not specific enough to provide a lead to the diagnosis. Bone scans and computerized tomography scans should be performed in all cases, to show the extent of vertebrae or calvarium infiltration by the tumor. To prevent recurrence and malignant transformation, the tumor should be completely removed whenever possible. If tumor excision is incomplete, a continuous follow-up is necessary to detect any recurrence or malignant transformation, which normally appears 5-10 years after the first operation (in one of our cases 7 years later).

Adult↗
PubMed1990

Vaginal gamete intrafallopian transfer. Experience with 14 cases.

A procedure utilizing transvaginal aspiration of stimulated gametes followed by transcervical, ultrasound-guided catheterization of the tubal ostia was performed as a modification of the standardized gamete intrafallopian transfer (GIFT) technique. Among 14 patients with 16 cycles there were four normal, intrauterine pregnancies and one ectopic pregnancy. In two patients the beta-human gonadotropin level rose significantly and then started to fall; the patients aborted spontaneously. The procedure can be performed with a higher degree of patient acceptance than can traditional GIFT, and the success rate in this small series was promising.

Adult↗