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Biomedical subjects

R Thomas

Publications and source records attributed to R Thomas.

At least 757 records · Page 42Linked to original sources
PubMedDate not supplied

[Water intoxication in psychiatric patients. 13 cases of severe hyponatremia].

Water intoxication mostly occurs in psychiatric patients. We observed 13 episodes of severe hyponatremia (less than 120 mmol/l) following a period of increased water consumption in 10 psychiatric patients (5 men, 5 women, mean age 48.8 years) treated with neuroleptics and/or benzodiazepines. Other causes of hyponatremia were excluded. The initial clinical signs were associated with severe gastrointestinal and neurological disorders requiring intensive care. In every case a gradual return to normal of natremia was obtained by creating a negative water balance while compensating for the sodium loss. From a study of urine and plasma osmolality ratio (U/P osm) on admission, several physiopathological mechanisms could be envisaged. A U/P osm ratio lower than 1 (6 cases) suggested a water intake exceeding the maximum dilution capacity of the kidneys (20-25 1), or a lesser water intake with little or no osmolal intake, or again an intrarenal disorder of urine dilution. When the U/P osm ratio was higher than 1 (7 cases), reflecting inappropriate secretion of the antidiuretic hormone, the hyponatremia could be explained by the psychosis itself, the treatment taken by the patients, a disorder of thirst regulation and/or a non-osmotic stimulation of vasopressin. This population, therefore, was heterogeneous: the mechanisms which contribute to this pathology are not fully elucidated, and they probably involve several factors.

Adult↗
PubMedDate not supplied

Ibuprofen use to reduce the incidence and severity of bronchopulmonary dysplasia: a pilot study.

OBJECTIVE: To assess the safety and efficacy of ibuprofen in reducing the incidence and severity of bronchopulmonary dysplasia (BPD) in preterm infants. METHODS: A total of 18 premature infants between 23 and 28 weeks' gestation were studied. Ibuprofen (10 mg/kg of loading dose followed by 5 mg/kg every 12 hours) was administered intravenously or orally to nine infants on respiratory support at > or = 7 days of age and was continued until 28 days of life or until the infants were spontaneously breathing room air, whichever occurred earlier. Ibuprofen levels in plasma were measured in five of these infants. The outcome variables (BPD, ventilatory parameters, and complications) in the study group were compared with those in nine matched controls treated conventionally. RESULTS: The incidence of BPD at 36 weeks postconceptional age was similar in both groups (eight of nine in each group). The percentage of oxygen requirement, the ventilatory efficiency index, and steroid use were also similar in both groups. One infant in the study group, who was also receiving steroids and aminophylline, developed gastrointestinal hemorrhage. Reversible renal failure in one infant and necrotizing enterocolitis in another infant were seen at 4 and 21 days, respectively, after the last dose of ibuprofen. There was no difference in the incidence of intraventricular hemorrhage between the two groups. Plasma levels of ibuprofen at 3 hours after the first dose ranged from 10.3 to 36 mg/liter. Study infants tolerated the feeds better and achieved the full enteral goal earlier than controls (p = 0.04). CONCLUSION: Although a trend toward less ventilator and hospital days in the ibuprofen group was observed in this pilot study, the differences were not statistically significant. The incidence of BPD was similar in both groups. In the study group, two infants developed gastrointestinal complications and a third infant experienced reversible renal failure. The plasma ibuprofen levels were low. Further studies are needed to assess the use of ibuprofen for the prevention and/or treatment of BPD in preterm infants.

Administration, Oral↗
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FISH mapping and identification of canine chromosomes.

The karyotype of the domestic dog (Canis familiaris) is widely accepted as one of the most difficult mammalian karyotypes to work with. The dog has a total of 78 chromosomes; all 76 autosomes are acrocentric in morphology and show only a gradual decrease in length. Standardization of the canine karyotype has been performed in two stages. The first stage dealt only with chromosomes 1-21 which can be readily identified by conventional G-banding techniques. The remaining 17 autosomal pairs have proven to be very difficult to reliably identify by banding alone. To facilitate the identification of all canine chromosomes, chromosome-specific paint probes have been produced by DOP-PCR from flow-sorted dog chromosomes. Each paint probe has been used for FISH to identify the corresponding chromosome(s), allowing precise identification of all 78 canine chromosomes. The identification of the undesignated 17 autosomal pairs has been agreed upon by the standardization committee during the second stage of their role. Cosmid clones containing microsatellite markers may now be conclusively assigned to their chromosomal origin by simultaneous dual-color FISH with the corresponding paint probe. In this way a collection of chromosome-specific cosmid clones is being constructed, comprising at least one marker per chromosome, which will allow anchoring of existing and future linkage groups to the physical map.

Animals↗
PubMedDate not supplied

Use of cosmid-derived and chromosome-specific canine microsatellites.

The majority of microsatellite markers being used to generate the emerging genetic linkage maps of the dog are derived from small-insert, random clones. While such markers are easy to generate, they have the disadvantage that they cannot easily be physically mapped by fluorescence in situ hybridization (FISH), making it difficult to assess the extent of genome coverage represented by such maps. In contrast, microsatellite markers from large-insert libraries enable the linkage groups within which they fall to be physically anchored to specific chromosomes. One aim of our work is to identify at least one microsatellite-containing cosmid clone for each canine chromosome, to ensure that linkage groups exist for all chromosomes. This is particularly important for a species with as complex a karyotype as the dog. Locating two cosmids on each chromosome would allow the orientation of the linkage groups to be established. Chromosomal locations of cosmid clones containing microsatellites have been determined by FISH and confirmed using canine chromosome-specific paints. Microsatellite sequences have been genotyped on the DogMap reference family. Microsatellites derived from flow-sorted, chromosome-specific libraries represent another source of useful markers. Initial studies have been carried out on the canine X chromosome, on which markers were underrepresented in our initial studies.

Animals↗
PubMedDate not supplied

Effect of verapamil on regional myocardial contraction during graded ischemia in the dog.

Verapamil benefits patients with angina pectoris during exercise. The mechanism underlying this effect is controversial. A direct oxygen-sparing effect on ischemic myocardium has been proposed, but previous studies seeking to demonstrate this effect have been inconclusive because of inadequate control of systemic hemodynamics. This study has assessed the direct effects of verapamil on regional myocardial contraction during graded coronary flow reductions while blood pressure and heart rate were held constant. Verapamil caused a decrease in regional contraction at normal levels of coronary flow, a finding consistent with a negative inotropic effect. At lower coronary flows, however, ischemic dysfunction was similar in the presence and absence of verapamil. These findings fail to support the concept that verapamil either selectively depresses ischemic myocardium or enhances myocardial function during ischemia. Thus, these direct mechanisms would seem unlikely causes of the observed beneficial effect during exercise in patients with coronary artery disease.

Angina Pectoris↗
PubMedDate not supplied

Orthopaedic aspects of prune belly syndrome.

Prune belly syndrome is a relatively uncommon disorder that is characterized by intrauterine urinary obstruction associated with cryptorchisdism, oligohydramnios, and orthopaedic deformations. The oligohydramnios is believed to produce limited intrauterine space, which in turn leads to fetal compression and the resultant deformities. The deformities observed in our patients were developmental dislocation of the hip (DDH), clubfeet, metatarsus adductus, vertical talus, and congenital muscular torticollis. These deformations should be treated aggressively because children with prune belly syndrome may be expected to have a relatively normal life if their renal function is good. The one exception is that as infants these children are very susceptible to pulmonary infections because of their inability to cough. Therefore, treatment of the hip and other deformations should be delayed until the children are old enough to be able to clear pulmonary secretions easily.

Adolescent↗
PubMedDate not supplied

Phaeohyphomycosis of the eye caused by Exserohilum rostratum in India.

A 40-year-old woman developed a corneal ulcer with hypopyon following a traumatic episode. In a KOH mount dematiaceous, septate, branched hyphae were demonstrated, and heavy growth of Exserohilum rostratum was obtained in culture. No bacterial pathogens were isolated. The patient was treated with natamycin and subsequently with ketoconazole. In spite of antimycotic therapy a descemetocele of the eye remained. This observation represents the first documented case of an Exserohilum infection in India.

Adult↗
PubMedDate not supplied

Long-acting versus short-acting cephalosporins for preoperative prophylaxis in breast surgery: A randomized double-blind trial involving 1,766 patients.

Postoperative infectious complications after breast surgery may result in significant morbidity, psychological trauma, and additional costs. We assessed the efficacy of preoperative antibiotic prophylaxis for surgery in a randomized, double-blind trial of 1,766 patients undergoing breast surgery. From January 1, 1996 to August 31, 1997, all eligible patients were assigned randomly to receive a single dose of ceftriaxone (2 g) or ceftazidime (2 g) given intravenously at the induction of anesthesia, with no further doses. The groups were similar with respect to age, operative procedure, operative time and time to discharge after operation. The patients who received ceftriaxone prophylaxis had 54. 4% fewer overall infections than those who received ceftazidime prophylaxis. Wound infection occurred in 0.45% of the ceftriaxone recipients (2 of 883) and 0.91% of the ceftazidime recipients (8 of 883). This prospective randomized double-blind study showed that the long-acting regimen containing ceftriaxone is more cost-effective than the short-acting ceftazidime in preventing postoperative infections in patients subjected to breast surgery.

Adult↗
PubMedDate not supplied

Development and evaluation of an in vivo mouse model for studying myocutaneous flap microcirculation and viability before and after suturing or stapling.

A model was developed in albino hairless mice to study microcirculation and viability of dorsal distally based myocutaneous flaps. The efficacy of this model was tested in 120 mice by evaluating the effects of excessive crimping and tension attributed to Proximate or Signet staples or to simple or mattress nylon sutures. Microhemodynamics were assessed using computer-assisted intravital videomicroscopic and electro-optical methods. Volumetric rates of blood flow were calculated within terminal arterioles from measurements of internal diameter and mean centerline cellular velocity. The viability was determined on day 5 by measuring the areas of necrosis (mm2) along the cut edges of these flaps. In 80 mice, flaps were elevated and examined at 0 h and then again at 24 or 48 h. There were 40 mice in each of these disturbed groups. In a third group of 40 mice, flaps were raised at 0 h without videomicroscopic examination at 0, 24, or 48 h (undisturbed group). All flaps were stapled or sutured to the original donor site with one of the four methods of closure. The results of this study indicate that sutures produce the highest incidence of necrosis at 5 days when compared to staples in the undisturbed groups of mice. However, no significant differences in necrosis were observed when flaps were disturbed at 48 h despite videomicroscopic evidence of depressed blood flow along their cut edges. In contrast, results at 24 h were equivocal and statistically not significant. These data suggest that the phenomenon of delay and/or flap recirculation following removal and reapproximation of sutures or staples drastically improves perfusion and viability of disturbed flaps.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

The use of two-stage Molteno implants in developmental glaucoma.

Developmental glaucoma, which cannot be controlled by conventional techniques, poses a difficult problem. Twenty-three eyes of 18 patients with developmental glaucoma underwent a two-stage implantation of the double template Molteno valve with follow-up between 12 and 84 months. The final pressure with medication was less than 21 mm Hg in 78% of the cases. These results were obtained in four out of four eyes with primary congenital glaucoma, six out of eight eyes with secondary congenital glaucoma, and eight of 11 eyes in which glaucoma followed surgery for congenital cataract. We feel that two-stage implantation of Molteno valves has a place in the management of difficult developmental glaucomas and is a reasonable early option when glaucoma occurs following surgery for congenital cataract.

Child↗
PubMedDate not supplied

Outcome of laser peripheral iridotomy in chronic primary angle closure glaucoma.

BACKGROUND AND OBJECTIVES: To report the effect of laser peripheral iridotomy on the angles of eyes with chronic angle closure glaucoma. PATIENTS AND METHODS: The hospital records of 171 consecutive patients with chronic primary angle closure glaucoma (CPACG) seen between October 1994 and March 1997 were analyzed to study the gonioscopic outcome of laser peripheral iridotomy (LPI). Success was defined as open angles (with or without medications for intraocular pressure (IOP) control) following LPI at the 1 month follow-up. RESULTS: Forty-seven eyes of 34 patients had chronic appositional angle closure glaucoma (CAACG), and 186 eyes of 124 patients had chronic synechial angle closure glaucoma (CSACG). Seventy eyes of 57 patients that underwent primary trabeculectomy for advanced disease were excluded from the study. Two hundred thirty-three eyes of 158 patients underwent LPI; the angles could be opened in 171 eyes (73.4%; confidence interval 67.7% to 79.1%) of 117 patients. Medications to control the IOP were required in 25 eyes (10.7%) of 19 patients. Fifty-four eyes of 34 patients that did not respond to LPI underwent argon laser gonioplasty. Gonioplasty was successful in opening at least 180 degrees of the angle in all eyes. There was no significant difference in success between CAACG (74.5%) and CSACG (73.1%). Age, IOP, and field loss were not predictors of outcome. There was perfect concordance of results between the 2 eyes of patients who had bilateral LPI. CONCLUSIONS: In this series, laser iridotomy was successful in opening the angle in 73.4% of eyes. Gonioplasty opened the angle in all eyes that underwent this procedure. The effect of iridotomy on one eye was predictive of the effect on the fellow eye.

Chronic Disease↗
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Immunohistochemical reactivity of anti-melanoma monoclonal antibody 225.28S in human breast cancer biopsies.

The high molecular weight melanoma-associated antigen, defined by murine monoclonal antibody (IgG1) 225.28S is largely expressed by melanoma cells and weakly expressed by other human tumors originating from neural crest. In this study, we analyzed the immunohistochemical reactivity of MoAb 225.28S in human breast cancer biopsies. A total of 92 breast cancer biopsies (66 infiltrating lobular and 26 infiltrating ductal carcinomas) were initially tested along with 26 melanomas (positive controls), 23 gastric/colonic adenocarcinomas and 13 neuroendocrine tumors. Forty-four out of 66 lobular breast carcinomas showed positive immunostaining with 225.28S MoAb as well as only 6 out of 26 infiltrating ductal histotype and 12 out of 26 melanomas. Conversely, gastric and colonic adenocarcinomas and neuroendocrine tumors were completely negative. The pattern of positivity in breast carcinomas was associated with malignant cells, rather than with the stroma or histiocytes infiltrating the lesions. Nonspecific cross-reactivity of 225.28S with breast carcinomas was excluded using a similar murine antithyreoglobulin MoAb, which gave negative staining in all biopsies. These results indicated that HMW-MAA or a similar sequence recognized by 225.28S MoAb is often expressed by lobular breast carcinomas but rarely by ductal adenocarcinomas. This seems to suggest that lobular breast carcinoma has common "ancestor" antigens with melanoma.

Antibodies, Monoclonal↗
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Immediate breast reconstruction with the transverse rectus abdominis musculocutaneous flap after skin-sparing mastectomy.

Immediate breast reconstruction with the transverse rectus abdominis musculocutaneous (TRAM) flap after skin-sparing mastectomy is becoming an increasingly performed procedure in patients with ductal carcinoma in situ, early invasive breast cancer, and prophylactic mastectomy. Through a periareolar approach, it is possible to remove the breast parenchyma along with the nipple areola complex, preserving almost all the original skin envelope and the inframmamary fold. The TRAM flap is used to recreate the volume and shape of the original breast. This technique has higher quality and easier reconstruction. The major disadvantages, extensive scar and donor site skin color mismatch, are reduced to a minimum level because the former is limited at the natural border of the nipple areola and the latter can be effectively concealed with proper nipple reconstruction. Thirty-one patients with a mean age of 39 years (range, 26-50 years) who had undergone unilateral or bilateral mastectomy for early breast cancer and immediate breast reconstruction with the pedicled TRAM flap were retrospectively reviewed. Requirements for the skin-sparing mastectomy technique include suitability of donor site tissue for autologous tissue, early breast cancer or ductal carcinoma in situ, and adequate size and shape matching of the contralateral breast. There was no observed local recur- rence during the follow-up period (mean, 20 months; range, 11-30 months). Complications at the recipient site include mastectomy skin flap partial necrosis in 2 patients and cellulitis of the transferred flap in 1 patient. No total or partial flap necrosis was observed. One patient developed abdominal bulging 1 month after the operation, during the administration of chemotherapy. All reconstruction was considered very satisfactory from an aesthetic perspective by the surgeon and the patient. The nicer aesthetic result with oncological safety is achieved with immediate breast reconstruction with the TRAM flap after skin-sparing mastectomy. The risk of local recurrence is not higher compared with more radical surgical techniques.

Adult↗