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Biomedical subjects

V Smith

Publications and source records attributed to V Smith.

At least 109 records · Page 6Linked to original sources
PubMed1990

Semiautomated preparation of DNA templates for large-scale sequencing projects.

The rate limiting step in a large-scale sequencing project is the generation of single-stranded DNA templates. We describe a fast, semiautomated procedure, using 96-well microtitre plates, in which 192 templates can be readily prepared in 1 day. The technique can be carried out manually or can be semiautomated using a robot pipetting device. We also provide evidence for the reliability and applicability of this method to a large-scale sequencing project.

Bacteriophages↗
PubMed1989

Histocompatibility determinants in childhood postinfectious encephalomyelitis.

Postinfectious encephalomyelitis and multiple sclerosis have clinical, immunologic, and neuroradiographic similarities. We studied HLA determinants in six white children consecutively diagnosed with postinfectious encephalomyelitis. Each of the children had HLA determinants which have been associated with multiple sclerosis. Relative risk (RR) calculations demonstrated that these antigens and genotypes occurred significantly more often in patients with postinfectious encephalomyelitis than in the control population (A3, RR 6.14; B7, RR 6.14; DR2, RR 4.51; A3B7, RR 9.36; A3DR2, RR 5.83; B7DR2, RR 6.13; A3B7DR2, RR 10.90). These data suggest that children with postinfectious encephalomyelitis are genetically predisposed to this demyelinating disease. Although the same HLA determinants were found in these patients as in those with multiple sclerosis, studies of a larger number of postinfectious encephalomyelitis patients will be needed before it can be concluded that the two diseases share a common genetic propensity.

Child↗
PubMed1987

Thyroid hormone modulation of thyrotrophin-releasing hormone (TRH) and TRH-Gly levels in the male rat reproductive system.

Thyrotrophin-releasing hormone (TRH) occurs in high concentrations in the rat ventral prostate and its concentrations is regulated in a positive dose-response manner by testosterone in castrated rats. alpha-Amidation of the tetrapeptide precursor, TRH-Gly, is a rate-limiting step in TRH biosynthesis. To investigate further the hormonal regulation of TRH biosynthesis in prostatic tissue, Sprague-Dawley rats of approximately 250 g were injected s.c. with either physiological saline or 3 mg propylthiouracil (PTU) daily for 5 days. The reproductive tissues were boiled in acetic acid (l mol/l), dried and extracted with methanol. The methanol extracts were measured for TRH immunoreactivity (TRH-IR) and TRH-Gly-IR by radioimmunoassay. Hypothyroidism induced by PTU significantly increased TRH-IR and TRH-Gly-IR levels in prostate and testis and reduced these levels in epididymis but did not affect the serum concentrations of testosterone compared with those of controls. Corresponding changes in TRH and TRH-Gly in the rat prostate were established by high-pressure liquid chromatography. To control for possible pharmacological effects of PTU on TRH biosynthesis, additional experiments were carried out on castrated rats receiving testosterone replacement and treatment with PTU plus methimazole. Treatment with thyroxine (T4) significantly reduced the increase in prostatic TRH levels due to hypothyroidism, despite the drug-induced blockade of the conversion of T4 to tri-iodothyronine. These effects parallel similar observations made in rat spinal cord and pancreas. This study demonstrates that in the male rat reproductive system the levels of TRH and its immediate biosynthetic precursor, TRH-Gly, are regulated by thyroid hormones.

Animals↗
PubMed1986

A simple method for cloning leishmanial promastigotes.

A method of cloning leishmanial promastigotes is described in which mid-exponential phase cultures are diluted to contain approximately 3 X 10(3) promastigotes per ml. Hanging-drop preparations made from 0.2-0.4 microliter volumes of the diluted culture seen to contain a single promastigote are picked-up in glass capillary tubes. Additional culture medium is taken into the capillaries which are then heat-sealed and incubated at 22 degrees C. Growth of leishmanial promastigotes inside the sealed capillary tubes is followed by direct microscopic observation through the walls of the tubes. When active promastigotes are seen the contents of the tubes are inoculated into small volumes of culture medium. The method is extremely easy to use, requires no specialised apparatus, and has been successfully used with different strains and species of Leishmania, with up to 100 percent of the cloned organisms growing.

Animals↗
PubMed1986

Interstitial microwave hyperthermia in a canine brain model.

A dual frequency microwave system was constructed for interstitial heating of brain tissue. Single-junction dipole antennas were tested in a phantom model and in normal dog brain to determine how variations in physical factors affected temperature distributions. Non-survival studies were performed at both 915 and 2450 MHz to determine heating patterns that could be achieved within normal brain using this system. Chronic survival studies were performed using a single dipole antenna inserted laterally into one hemisphere of brain and driven at 2450 MHz. Temperatures of 43 or 44 degrees C for 30 min at a reference point 0.5 cm from the antenna junction were used to induce a thermal lesion of approximately 1 cm diameter in the right cerebral hemisphere of dogs. Neurologic and physical changes in dogs were monitored daily for up to 16 weeks after induction of cerebral lesions. The extent and development of thermal lesions was monitored with weekly computed tomographic (CT) examinations and, after death, at histopathologic examination. Results of the phantom studies showed that the longitudinal heating pattern was bell-shaped at both frequencies used and that there was some variation in heating length that depended on insertion depth. Acute studies in dog brain showed that 915 MHz antennas implanted less than 6.5 cm deep produced erratic heating patterns that usually included excessive heating of the surface of the brain. Conversely, 2 cm-long antennas driven at 2450 MHz gave reproducible temperature distributions both longitudinally along and radially away from the antenna. The steepest gradients--about 1 degree C/mm--occurred in the radial direction away from the antenna junction. A single 30 min heat treatment produced a large focal lesion that consisted of central coagulation necrosis surrounded by a sharply demarcated hypervascular zone. Edematous changes were minimal and were observed only during the first week after treatment. As assessed by serial CT scans, thermal lesions reached a maximum size by the first week after treatment and were essentially resolved by 16 weeks after treatment.

Animals↗
PubMed1986

Effectiveness of foaming antacid in relieving induced heartburn.

A double-blind, placebo-controlled, randomized crossover study was made of 60 patients with chronic heartburn to test the efficacy of foaming antacid in promoting symptom relief. Heartburn was induced by a meal consisting of chili, black coffee, and a spicy tomato drink mix. Of the 60 patients, 40 (67%) had relief within 15 minutes after taking foaming antacid tablets as compared to only 17 (28%) after taking a placebo. The difference in response was significant (P less than .05). Foaming antacid appears to be an effective therapy for acute postprandial heartburn.

Adolescent↗
PubMed1985

Leishmania infecting man and wild animals in Saudi Arabia. 1. General survey.

Using up to 13 enzymes, biochemical characterization of 75 isolates of Leishmania made from man, wild animals and sandflies from a wide variety of localities in the Kingdom of Saudi Arabia has revealed the presence of L. major (two similar zymodemes), L. tropica (two zymodemes) and a parasite of the L. donovani-L. infantum complex. Zymodeme LON-4 of L. major has been found in 52 of 53 isolates so far characterized from man, from one specimen of Phlebotomus papatasi, from 15 Psammomys obesus, from one Meriones libycus and from one dog. One isolate from man has been identified as a new variant of L. major. This variant, zymodeme LON-65, varies from zymodeme LON-4 in a single enzyme. While this is the only example of zymodeme LON-65 identified so far, zymodeme LON-4 has also been obtained from Kuwait and Iraq. These are the first reports of L. major in Meriones libycus from Saudi Arabia and the first proven isolate from the dog in any country. L. tropica was identified from only two foci, whereas L. major appears to be widely distributed in the Kingdom. Two infants with kala-azar were found to be infected with a parasite apparently identical to zymodeme LON-42 of L. donovani (sensu lato) which also occurs in the highlands of Ethiopia.

Animals↗
PubMed1985

alpha-Fetoprotein elevation and proteinuric pre-eclampsia.

In a retrospective study of pregnancy complicated by unexplained elevation of maternal serum alpha-fetoprotein (AFP), 60 patients were compared with 120 control subjects. Proteinuric pre-eclampsia occurred in 13% of the study patients compared with 1% of the control subjects. Primiparity, previous mid-trimester abortion and recurrent abortions were also significantly more common in the study group. It is proposed that an abnormality of the placenta predisposes to complications and that this abnormality is expressed early in pregnancy when the AFP level is first measured. This group of women is at high risk of adverse pregnancy outcome and requires careful monitoring.

Abortion, Spontaneous↗
PubMed1984

Selenium availability in Texas: possible clinical significance.

In light of recent reports that have indicated that selenium is an essential micronutrient and possible natural cancer inhibitor, data on the geographic distributions of selenium in Texas were gathered and compared with the distribution of age-adjusted cancer mortality rates. We considered concentrations of selenium measured in ground and surface water to be indicators of its presence in rocks, soil, and locally grown crops. Texas water sources were found to be poor in selenium, except for the Panhandle and the West Texas regions, where soil consists of erosion products from the selenium-rich Rocky Mountains. In general, lower cancer mortality was observed for the selenium-rich regions of Texas compared with cancer mortality for the selenium-poor regions. Even though the risks from cancer-provoking factors also differed geographically, the observed pattern was sufficiently suggestive to warrant further attention to selenium.

Female↗
PubMed1983

Randomised controlled comparative study of methyldopa and oxprenolol in treatment of hypertension in pregnancy.

One hundred pregnant women with hypertension (defined as diastolic blood pressure at or above 95 mm Hg) were allocated at random to treatment with methyldopa or oxprenolol and were compared with nonhypertensive controls matched according to parity and gestation at delivery. The patients were also stratified into those entering the study early (before 32 weeks' gestation) and those entering late (after 32 weeks' gestation). Although there were no differences in diastolic blood pressure between the hypertensive groups before or during treatment, in the early entry group the systolic blood pressure at entry of those allocated to oxprenolol was significantly higher than that of those receiving methyldopa; this difference remained throughout the treatment period. Also in the early entry group further increments of drug treatment were required to control blood pressure of patients receiving oxprenolol than in those receiving methyldopa. The eventual fetal outcome for all patients treated with methyldopa was the same as that for those treated with oxprenolol; birth weight, placental weight, head circumference, and Apgar score were not significantly different and there were no stillbirths in either group.

Adult↗
PubMed1983

Micro-counterimmunoelectrophoresis: a rapid screening technique for trypanosomiasis.

A rapid and economical micro-counterimmunoelectrophoresis (MCIE) test, for antibody to trypanosome antigens, has been developed which may prove useful in trypanosomiasis surveillance. MCIE was more sensitive and more rapid than immunodiffusion (ID). Serum samples from trypanosome-infected rabbits and cattle (Nigerian and Gambian), from Kuwaiti dogs and camels, from Ivory Coast sleeping sickness patients, from Brazilian patients with Chagas's disease, plus mouse-anti-malaria sera have been tested by MCIE with Trypanosoma brucei, T. vivax, T. congolense and T. cruzi antigens. A few of the rabbit and the mice sera were also tested against Trichomonas vaginalis, Entamoeba histolytica, Plasmodium berghei or P. chabaudi antigens. Whenever possible the MCIE results were compared with parasitological or other serological tests (ID; indirect fluorescent antibody test, IFAT; enzyme-linked immunosorbent assay, ELISA; complement fixation test, CFT or indirect haemagglutination test, IHAT). The MCIE test was not species specific but the homologous species reactions were more often positive than heterologous ones. Homologous species reactions, with rabbit sera, detected antibodies as early as 10 days after infection and developed more precipitin lines as the infection progressed. Trypanosomal antigens and antisera cross-reacted with those of other protozoa (E. histolytica, Tr. vaginalis, P. chabaudi, P. berghei, and Babesia sp. and Leishmania sp.) but such reactions required an antigen concentration 4 to 16 times greater than that required for homologous trypanosome reactions (a factor which might be exploited for identification of different species of trypanosome).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

The polypeptide profiles of strains of the Trypanosoma subgenera Schizotrypanum and Trypanozoon: peptideme characterization.

Examination, by SDS-PAGE, of the polypeptide profiles of 36 Brazilian strains of Trypanosoma (Schizotrypanum) cruzi has revealed five peptidemes (subpopulations having similar polypeptide profiles) recognizing differences not apparent from zymodeme analysis. T. cruzi zymodeme (Z)1 has been subdivided into peptidemes 3, 4 and 5 (one example of Z2 was included in peptideme 5). Peptideme 1 consisted mostly of Z2 strains except for one example each of Z1 and Z3. One strain of Z2 (Tc 003) was sufficiently dissimilar to merit separation into peptideme 2. Peptideme characterization was not possible with the Trypanozoon trypanosomes since there were no significant differences in the polypeptide profiles of 56 strains from Africa and South America; their profiles could only be compared in the molecular weight ranges 94,000 to 70,000 and below 36,000 because of distortion resulting from the variant specific surface glycoproteins. It was possible to differentiate between eight VATs of T. (Trypanozoon) brucei (BruTat 2 to 9) by isoelectric focusing of their soluble proteins.

Animals↗