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Biomedical subjects

R L Thomas

Publications and source records attributed to R L Thomas.

At least 19 recordsLinked to original sources
PubMed1992

Vertebral hypersegmentation in a case of the VATER association.

Associations are statistical clusterings of malformations not known to be polytopic field defects, sequences, or syndromes. The VATER association is a nonrandom association of malformations including vertebral, anal, cardiovascular, tracheoesophageal, genitourinary, and limb defects. The caudal "dysplasia" sequence of lumbosacral vertebral defects, genitourinary abnormalities, and imperforate anus overlaps the VATER association. The cloacal membrane agenesis sequence is a pattern of malformations resulting in the absence of anal, genital, and urinary orifices with associated malformations in surrounding structures. We report on a 37-week gestation liveborn male with oligohydramnios deformations, tetralogy of Fallot, "H-type" tracheoesophageal fistula, duodenal atresia, imperforate anus, urethral atresia, undescended testes, absent right kidney with a small dysplastic left kidney, a "cloacal-like" abnormality of the bladder and distal bowel, and thoracic and lumbar vertebral hypersegmentation. This patient has manifestations of the VATER association, the caudal dysplasia sequence, and the cloacal membrane agenesis sequence. We propose that some of his defects may represent a malformation sequence secondary to excessive embryonic flexion resulting from vertebral hypersegmentation.

Abnormalities, Multiple↗
PubMed1992

Determination of profiles of non-collagenous proteins from rat bones by sodium dodecyl sulfate high-performance liquid chromatography.

Sodium dodecyl sulfate-high-performance liquid chromatographic (SDS-HPLC) techniques for screening profiles of bone non-collagenous proteins (NCP) are described and compared with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) techniques. NCPs were obtained from long bones of neonatal and mature rats by sequential extraction with 4 M guanidine hydrochloride (GdnHCl) and 0.25 M EDTA followed by desalting. Desalted extracts were subjected to SDS-PAGE and SDS-HPLC. The results of the two analyses were comparable. There were differences in NCP profiles between mature rats and pups and between the GdnHCl and EDTA extracts. The methods described can be used for qualitative comparison of treatments and as a basis for further study.

Animals↗
PubMed1992

Prenatal diagnosis of giant cystic hygroma: prognosis, counselling, and management; case presentation and review of the recent literature.

Cystic hygromas have historically been associated with a grim prognosis when discovered during prenatal sonographic study of the fetus. This same grim prognosis is not observed by the paediatric surgeon who evaluates the neonate or paediatric patient. We present a fetal patient with a massive anterior cystic hygroma discovered in the third trimester prior to 30 weeks. This case and a review of the literature suggest tailoring the prognosis by category when counselling patients: (1) first trimester, normal karyotype--good; (2) first trimester, abnormal karyotype--poor; (3) second trimester and early third--poor to guarded; and (4) mid to late third trimester--good.

Adult↗
PubMed1992

Patterns of alcohol consumption in white collar-workers--a cross-sectional and longitudinal study.

A 6-year follow-up of a cohort of male and female white collar workers in whom there was baseline information on alcohol consumption and access to data on sickness absence, promotion and labour turnover, revealed that even moderate alcohol and consumption in this population was associated with social costs for the employer and the employee, particularly in terms of sickness absence. The longitudinal examination of consumption in this study suggests that early intervention in a drinking career may reduce alcohol consumption and consequently avoid years of morbidity and sickness absence, as well as having a favourable influence on promotion prospects and labour turnover.

Adult↗
PubMed1992

A six year longitudinal study of the occupational consequences of drinking over "safe limits" of alcohol.

Although much research has focused on the psychological, social, and economic consequences of heavy problem drinking, there has been far less attention paid to the consequences of "moderate" drinking. This study used a unique opportunity to carry out a six year follow up of a cohort of male and female white collar workers in whom there was baseline information on alcohol consumption and access to details on sickness absence, labour turnover, and promotion. It has provided evidence that even moderate alcohol consumption in the working population is associated with social costs for the employer and the employee, including substantial sickness absence, and lack of promotion in men, although the increase in labour turnover was not statistically significant. The longitudinal examination of consumption in this study suggests that early intervention in a drinking career may reduce alcohol consumption and consequently avoid years of morbidity and sickness absence, as well as having a favourable influence on performance and labour turnover.

Absenteeism↗
PubMed1992

Pregnancy complicated by Goodpasture syndrome.

Goodpasture syndrome is characterized by pulmonary hemorrhage, glomerulonephritis, and an autoantibody to glomerular basement membrane antigens. Current management of this potentially lethal disease consists of glucocorticoids to control pulmonary hemorrhage, cytotoxic drugs to inhibit further renal damage, and plasma exchange to clear circulating anti-basement membrane antibodies. These treatment modalities pose difficult management issues during pregnancy. We describe a successful pregnancy outcome in a parturient with Goodpasture syndrome. Antepartum care included serial pulmonary and renal evaluations. In patients without disease progression, a favorable outcome may be possible.

Adult↗
PubMed1991

Detoxification of pentachlorophenol and creosote contaminated groundwater by physical extraction: chemical and biological assessment.

Chemical analyses revealed that polycyclic aromatic hydrocarbons (PAHs) and other organic compounds were present in a perennial freshwater stream that flowed through the abandoned American Creosote Works and into Pensacola Bay, Florida. Moreover, groundwater pumped from a well depth of 21 m at a location adjacent to the site was heavily contaminated with PAHs and other organics. A study was conducted to determine the efficacy of ultrafiltration for removal of organics from groundwater at this U.S. Environmental Protection Agency, Super Fund site. Ultrafiltration reduced the concentration of total identified organics from 210.0 mg/L in groundwater to 1.5 mg/L in the post-filtration permeate. Tests for toxicity/teratogenicity in embryonic inland silversides, Menidia beryllina; and Microtox 15 min EC50's were conducted with: 1) streamwater, 2) untreated groundwater, 3) feedwater used in the ultrafiltration system and 4) permeate water that passed through the ultrafiltration system. A concentration of 100% streamwater caused significant (alpha less than or equal to 0.05) teratogenic responses in fish embryos and larvae; the Microtox EC50 was 3.7% streamwater. Groundwater and feedwater caused significant embryo toxic or teratogenic responses at concentrations of 100, 10, and 1%; the Microtox EC50's were 0.85 and 0.48%, respectively. In contrast, only 100% permeate water caused significant increases in terata, compared to the control response; at 10 and 1% concentrations greater than 90% of hatched larvae appeared normal. The Microtox EC50 was 30% permeate water.

Animals↗
PubMed1991

Precision of umbilical artery Doppler studies. Intraobserver, interobserver, and biologic variability of fetal Doppler velocimetry.

The use of Doppler ultrasound to study fetal blood flow has become commonplace, despite the lack of detailed evaluation of the testing tool for precision. In evaluation of 25 patients, no significant intraobserver differences were found between readings on an individual waveform, nor were there significant differences between different observers on individual waveforms. Temporally separated waveforms within a 30-minute window gave the greatest variation. A multi-way analysis of variance noted significant differences in this category only. This study confirmed the precision of measurements by a single observer and between observers. Only biological alterations over time displayed significant variability.

Analysis of Variance↗
PubMed1991

The relative value studies: fixed conversion vs. customary fees.1966.

Health care legislation, technological advances, increases in biological knowledge, better health and increasing longevity of people, changing patterns of professional activity, and changes in the structure and function of medical institutions are among the factors involved in the changes occurring in the character of the practice of medicine.

Delivery of Health Care↗
PubMed1991

Cervical pregnancy. A report of two cases.

Cervical pregnancy is a rarely occurring form of ectopic pregnancy. Given its rarity, the identification of risk factors is based on anecdotal case reports and occasional summarizing reviews. We managed two additional cases with a new, conservative approach. The trend is away from radical therapy and toward conservation of reproductive function.

Adult↗
PubMed1991

Aerobic and anaerobic microbiologic factors and recovery of beta-lactamase producing bacteria from obstetric and gynecologic infection.

Specimens obtained from 736 patients with obstetric and gynecologic infections were studied for aerobic and anaerobic bacteria. Bacterial growth was present in 714 specimens. These included 53 specimens of infected fallopian tubes, 470 of infected endometrium, 94 of infected amniotic fluid, 57 of aspirates of cul-de-sacs in instances of pelvic inflammatory disease, 14 labial and vaginal abscesses and 26 of Bartholyn's cyst abscess. A total of 2,052 isolates (2.9 per specimen), 1,139 anaerobes (1.6 per specimen) and 913 aerobic or facultative (1.3 per specimen) were recovered. The most commonly isolated anaerobic bacteria was Bacteroides species (566 isolates), which included Bacteroides bivius (151), Bacteroides fragilis group (130), Bacteroides melaninogenicus group (110) and Bacteroides ureolyticus (47). Others included an anaerobic gram-positive cocci (391), Clostridium species (48) and Fusobacterium species (36). The most frequently recovered aerobic and facultative bacteria were Lactobacillus species (169), Escherichia coli (85), Neisseria gonorrhoeae (62), Staphylococcus aureus (59) and Group B streptococcus (55). Three hundred and sixty-five (18 per cent) of the isolates recovered from 276 (39 per cent) patients were beta-lactamase producing organisms (BLPO); 222 (61 per cent) anaerobes and 143 (39 per cent) aerobes or facultatives. The most common BLPO were B. fragilis group, B. bivius, B. melaninogenicus, B. disiens, Enterobacteriaceae and S. aureus. These data illustrate the polymicrobial nature and important role of BLPO in obstetric and gynecologic infection.

Abscess↗
PubMed1990

Chorioangioma: a new inclusion in the prospective and retrospective evaluation of elevated maternal serum alpha-fetoprotein.

Two cases are presented which illustrate the association of elevated maternal serum alpha fetoprotein (MSAFP) levels and chorioangiomas. These cases emphasize the importance of ultrasound study of the placenta in MSAFP elevation evaluation. In addition, placentas from pregnancies with otherwise unexplained MSAFP elevations should be submitted for pathologic study. A definitive retrospective diagnosis may thus be provided.

Adult↗
PubMed1990

Penbutolol: a new beta-adrenergic blocking agent.

Penbutolol is a new beta-adrenergic blocking drug approved for the treatment of hypertension. It is a noncardioselective beta-blocker and has intrinsic sympathomimetic activity. The drug is approximately four times as potent as propranolol when taken orally. After oral administration, it is almost completely absorbed and peak plasma concentrations are achieved within 1.0 to 2.25 hours. Penbutolol is extensively metabolized in the liver by hydroxylation and glucuronidation. Active metabolites have not been identified. Only four to six percent of the parent drug is eliminated in the urine unchanged and dosage adjustment in renal insufficiency does not appear to be necessary. The mean terminal half-life of penbutolol is 17.6 to 26.5 hours. The duration of the hypotensive effect is approximately 24 hours. Current dosing guidelines recommend initiating therapy with 20 mg/d administered once a day. Optimum hypotensive effect occurs at dosages of 20-40 mg/d with little additional benefit observed above this range. Penbutolol appears to be well tolerated. The adverse effect profile is similar to other beta-blockers.

Animals↗
PubMed1990

Evaluation of elevations in maternal serum alpha-fetoprotein: a review.

Maternal serum AFP screening has had significant clinical impact on reducing unrecognized anencephaly and open neural tube defects at delivery. In addition, a growing number of other associations with maternal serum AFP elevations have become apparent since antepartum screening has become commonplace. We present in this review a clinically oriented approach to understanding the physiologic basis of maternal serum AFP elevations, both true- and false-positives. Compartmentalization of etiology, fetal and maternal, and routes of communication, amniotic fluid and placenta, allows a more logical approach to developing a differential diagnosis in this group of patients. In evaluating an elevation in maternal serum AFP, it is first necessary to consider the amount of fetal production by confirming the gestational age of the fetus and the number of fetuses present. Adjustments for maternal factors (weight, race, diabetes) must also be made. Fetal developmental defects which may lead primarily to leakage of the fetal proteins into the surrounding amniotic fluid with secondary elevations of maternal serum AFP enter into the differential diagnosis. The placenta itself is probably not a production source of AFP, but when the placenta is abnormal, a greater amount of AFP may be transported to the maternal circulation. Although our thoughts frequently do turn first to an increased maternal serum AFP reflecting an increased AFP concentration in the amniotic cavity with greater transference "across the membranes," in fact a far more common etiology is an increased transfer from the fetal circulation to the maternal via the fetal-maternal interface within the placenta. This is supported by the simple fact that the vast majority of maternal serum AFP elevations are not associated with amniotic fluid AFP elevations; the amniotic fluid AFP concentrations are usually normal. Thus, in circumstances where the fetal anatomy is grossly normal and there is not another explanation for elevations in maternal serum AFP, the placenta, either secondary to providing increased areas of transport or in providing an abnormal endothelial barrier, allows for greater transfer of fetal serum, and thus AFP, into the maternal compartment. An abnormal placenta is also a likely explanation for the increased risk of adverse pregnancy outcome that is associated with increased maternal serum AFP elevations for which no obvious etiology is found. The case herein reported suggests that an abnormal placenta which provides an altered interface for AFP flow between the fetal and maternal circulations may in fact be the etiology of the significant elevations of maternal serum AFP seen in cases of triploidy.(ABSTRACT TRUNCATED AT 400 WORDS)

Abnormalities, Multiple↗
PubMed1989

Separation by liquid chromatography (under elevated pressure) of benzyl and nitrophenyl glycosides of oligosaccharides.

Liquid chromatography under elevated pressure (l.c.) was employed for the separation of some benzyl and nitrophenyl glycosides of a variety of mono-, di-, tri-, and tetra-saccharides. The separation was conducted on a Waters Carbohydrate Analysis column by use of a mixture of acetonitrile-water as the mobile phase. In general, monosaccharides emerged first from the column, followed sequentially by di-, tri-, and tetra-saccharides. It was observed that the pattern of substitution imparts a noticeable effect on the elution profiles of isomeric oligosaccharides. Also, substitution of a hydroxyl group with a methyl group, or its replacement with a fluorine atom, led to a substantial decrease in retention times of some oligosaccharides. Moreover, resolution was clearly enhanced, and retention times were congruently increased by decreasing the water content of the mobile phase.

Benzyl Compounds↗
PubMed1989

Synthetic mucin fragments. Benzyl O-beta-D-galactopyranosyl-(1----3)-O-(2-acetamido-2-deoxy-beta-D- glucopyranosyl)-(1----6)-2-acetamido-2-deoxy-alpha-D-galactopyranoside and O-alpha-L-fucopyranosyl-(1----3)-O-(2-acetamido-2-deoxy-beta-D- glucopyranosyl)-(1----6)-2-acetamido-2-deoxy-D-galactopyranose.

Benzyl 2-acetamido-6-O-(2-acetamido-2-deoxy-4,6-O-isopropylidene-beta-D- glucopyranosyl)-2-deoxy-3,4-O-isopropylidene-alpha-D-galactopyranoside (2) was obtained by acetalation of its parent disaccharide with 2,2-dimethoxypropane in hot N,N-dimethylformamide and in the presence of 4-toluenesulfonic acid. Glycosylation of 2 with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide (catalyzed by mercuric cyanide), followed by removal of the protecting groups afforded the title trisaccharide 7. A second product was also isolated, which was identified as a derivative of 7 having a 2-cyanopropyl group. Glycosylation of diacetal 2 with 2,3,4-tri-O-benzyl-alpha-L-fucopyranosyl bromide (under catalysis by bromide ion), followed by systematic removal of the protecting groups furnished the title trisaccharide 13. The structures of both 7 and 13 were established by 13C-n.m.r. spectroscopy.

Magnetic Resonance Spectroscopy↗
PubMed1989

Triploid fetus: an important consideration in the evaluation of very high maternal serum alpha-fetoprotein.

Two patients referred for evaluation of very high maternal serum alpha-fetoprotein (10-20 multiples of the median) were carrying triploid fetuses with placentas showing features of partial hydatidiform mole. The diagnosis of fetal triploidy should be considered when there is a very high maternal serum alpha-fetoprotein and no ultrasound evidence of open neural tube defect, ventral wall defect, or any other explanation. Therefore, chromosomal analysis of amniotic fluid cells in such cases is essential.

Amniotic Fluid↗