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Biomedical subjects

B G Williams

Publications and source records attributed to B G Williams.

At least 55 records · Page 3Linked to original sources
PubMed1993

Deletion of WT1 and WIT1 genes and loss of heterozygosity on chromosome 11p in Wilms tumors in Japan.

Six of 39 sporadic Wilms tumors had gross homozygous or hemizygous WT1 and WIT1 deletions. Two Wilms tumor-aniridia-genitourinary abnormalities-mental retardation syndrome patients had total hemizygous WT1 and WIT1 deletions in both constitutional and nonsporadic type tumor cells. Four of the 8 tumors with WT1 and WIT1 deletions showed loss of constitutional heterozygosity (LOH) for markers limited to the 11p13 region. Seven of 19 Wilms tumors with neither WT1 nor WIT1 deletions also had LOH on 11p; 4 in the 11p15-11p13 region, one in the 11p15 and possibly also 11p13 regions, and two solely in the 11p15 region. Thus, 15 of the 41 Wilms tumors (37%) had WT1 and WIT1 deletions or LOH on 11p, and only 2 of the 27 tumors whose nonneoplastic normal tissues were available for study showed LOH limited to the 11p15 region. None of the 7 non-Wilms childhood renal tumors showed WT1 or WIT1 deletions, or LOH on 11p. These data suggest that Japanese Wilms tumors may be characterized by a higher incidence of the gross WT1 deletion and a lower incidence of LOH limited to the 11p15 region than the Caucasian counterparts. These molecular-genetic features may be contributing to the lower incidence of Wilms tumors in Japanese children than in Caucasian ones.

Blotting, Southern↗
PubMed1992

Modelling the effect of feeding-related mortality on the feeding strategy of tsetse (Diptera: Glossinidae).

Free-living haematophagous insects risk death through host grooming responses or through increased susceptibility to predation whenever they take a bloodmeal. In this paper we investigate the effects of these risks on the feeding strategy of tsetse. A model is presented that allows for death of tsetse by starvation if they do not succeed in feeding within a fixed time (set at 6 days in the first instance) and for mortality specifically associated with feeding. In addition there is background mortality that applies to all flies at all times. The model is used to compute the individual life-time fertility (number of female puparia per female) as a function of the probability of obtaining a meal (indicated by field data to be very high, usually > 0.85 per day) and the day on which flies start to search for a meal. We suggest that the feeding strategy that would be selected for is that which allows the maximum reproductive output. The model shows that this strategy involves making no attempts to feed for 3-4 days after the previous meal and then attempting to feed with the greatest possible probability until a meal is obtained. The predicted feeding interval, obtained independently of any trapping data, agrees closely with all previous estimates from field studies using a variety of methods. Preliminary results from a laboratory experiment reveal an increased risk of predation of recently fed as compared with hungry tsetse. The lower the actual feeding mortality the more frequently will flies be able to feed should conditions so demand. It is adaptive, however, for tsetse to delay attempting to feed for as long as they can, which is made possible by the near certainty of locating and feeding on a host within 1 day, using their sophisticated sensory systems.

Animals↗
PubMed1991

Control of tsetse flies and trypanosomiasis: Myth or reality?

The African trypanosomiasis are among Africa's most devastating diseases. The human disease, sleeping sickness, and the animal disease, nagana, are caused by trypanosomes, protozoan parasites transmitted by tsetse flies, Glossina spp. Attempts have been made to control tsetse and trypanosomiasis for over 70 years, supported by ever-increasing amounts of foreign aid. Although progress has been made in the control of sleeping sickness, this disease still persists in many countries. Nogono excludes cattle from many of the potentially most productive areas of Africa and is a major constraint on economic development. In this paper, Robert Dransfield, Brian Williams and Robert Brightwell review the control of tsetse and trypanosomiasis in the light of recent progress in our understanding of tsetse population dynamics, with special reference to the experience gained in tsetse control on a Maasai ranch at Ngurumon in the Rift Valley of Kenya, and make suggestions for the management and funding of future control programmes in relation to rural development.

Journal Article↗
PubMed1991

Quantitative assessment of HIV-1 DNA load by coamplification of HIV-1 gag and HLA-DQ-alpha genes.

We developed an assay for simultaneous amplification, detection and quantitation of HIV-1 gag gene and the DQ-alpha locus of the histocompatibility (HLA) region of the human genome by polymerase chain reaction (PCR). Crude cell lysates from control cell lines and peripheral blood mononuclear cells (PBMC) from HIV-1-infected and control individuals were coamplified using optimized concentrations of primers directed at both loci, followed by simultaneous hybridization with radioactively labeled HIV-1-gag and HLA-DQ-alpha probes. Simultaneous quantitation of the 242-base-pair HLA and 115-base-pair HIV products was accomplished by both end-point dilution analysis and image analysis of autoradiographs relative to standard curves derived from infected cell lines. We observed good agreement between input cell counts on fresh samples and the HLA-DQ-alpha target copy number values determined by both end-point dilution analysis and comparison of band intensities with standard curves. HIV-1 proviral load in symptomatic patients ranged from 200 to 4000 HIV-PCR-units per 1 x 10(6) PBMC (mean of 1245 copies), whereas asymptomatic patients had levels ranging from two to 1000 HIV-PCR-units per 1 x 10(6) PBMC (mean of 213 copies). This HIV/HLA coamplification approach should be particularly useful for analysis of frozen repository samples from natural history studies, and may facilitate wider application of quantitative PCR analysis.

Base Sequence↗
PubMed1991

An unusual cutaneous lymphoma with B and T cell characteristics showing gallium-67 positive benign thymic hyperplasia following intensive chemotherapy.

This case illustrates two interesting features. Firstly it describes an unusual cutaneous lymphoma in an adolescent girl. This lymphoma showed features of B and T cell lineages with rearrangements of both immunoglobulin heavy chain and T cell beta chain genes. Secondly it describes the development of gallium-67 citrate (67Ga) scan positive benign thymic hyperplasia, 15 months after diagnosis and three months after cessation of intensive chemotherapy.

Adolescent↗
PubMed1990

Molecular and hematologic characterization of Scottish-Irish type (epsilon gamma delta beta)zero thalassemia.

The DNA deletion associated with an example of (epsilon gamma delta beta)zero thalassemia (Scottish-Irish type) was characterized. The deletion is approximately 205 kb in length and involves the epsilon, G gamma, A gamma, delta, and beta globin genes. The breakpoint is located 263 bp 3' to exon 3 of the beta globin gene. An LI (KpnI) repeat element approximately 320 bp in size is found at the 3' end of the novel DNA sequence. Different clinical phenotypes for three heterozygous neonates suggest that the deletion alone does not predict severity of (epsilon gamma delta beta)zero thalassemia at this age.

Adolescent↗
PubMed1987

cDNA cloning and in vitro synthesis of the Dolichos biflorus seed lectin.

The Dolichos biflorus seed lectin contains two structurally related subunits. A cDNA library was constructed using RNA isolated from D. biflorus seeds actively synthesizing the seed lectin. The library was expressed in Escherichia coli using a lambda Charon 16 vector, and lectin-specific antiserum was used to isolate a seed lectin cDNA. Hybridization of the D. biflorus seed lectin cDNA to RNA isolated from seeds actively producing both lectin subunits identifies a single-size RNA of 1100 bases. An oligodeoxyribonucleotide probe, constructed from an amino acid sequence common to both lectin subunits, detects the same size RNA. Translation of seed mRNA in vitro and immunoprecipitation of translation products using a lectin-specific antiserum yields a single polypeptide of slightly higher molecular mass than the largest seed lectin subunit. This seed lectin precursor is indistinguishable from a polypeptide synthesized from mRNA hybrid selected by the seed lectin cDNA. These data support the existence of a single polypeptide precursor for both subunit types of the D. biflorus seed lectin and suggest that differences between the subunit types arise by posttranslational processing.

Amino Acid Sequence↗
PubMed1987

DNA changes during blastic transformation in chronic granulocytic leukemia.

Immunoglobulin and T cell receptor gene mapping were undertaken in 10 patients during both chronic and blastic phases of chronic granulocytic leukemia. Twenty percent were shown to undergo lymphoblastic transformation. DNA changes did not predict blastic transformation or those who would respond favourably to treatment with vincristine and prednisone.

Adolescent↗
PubMed1986

Accumulation of non-protein metal-binding polypeptides (gamma-glutamyl-cysteinyl)n-glycine in selected cadmium-resistant tomato cells.

Tomato cell suspensions have been selected for sustained growth on normally lethal concentrations of CdCl2. In cadmium-resistant (CdR) cells, Cd2+ is found complexed with non-protein, cysteine-rich polypeptides which accumulate in high amounts when cells are grown in the presence of Cd2+. Sequence and linkage analysis of these peptides by triple quadrupole mass spectrometry establishes structures of (gamma-Glu-Cys)3-Gly and (gamma-Glu-Cys)4-Gly. Necessity of these peptides for the CdR phenotype is demonstrated by inhibition of their accumulation by buthionine sulfoximine, a specific inhibitor of gamma-glutamylcysteine synthetase. Treatment of CdR cells with a concentration of buthionine sulfoximine below that inhibiting growth in the absence of Cd2+ renders CdR cells sensitive to Cd2+ ion.

Amino Acid Sequence↗
PubMed1985

Effect of Chilling Temperatures upon Cell Cultures of Tomato.

The effect of chilling temperatures upon cell cultures of tomato (Lycopersicon esculentum Mill cv ;VF36,' and cv ;VFNT Cherry,' and L. hirsutum Humb. & Bonpl.) was tested. Doubling times for L. esculentum were 2 to 3 days at 28 degrees C, and 3 to 8 days at 12 degrees C. No growth was observed at 8 degrees C, indicating an abrupt limit to growth between 8 and 12 degrees C. Fluorescein diacetate staining indicated that 80 to 90% of the cells were alive when cells were maintained at 8 degrees C for up to 2 weeks. When cultures kept at 8 degrees C for up to 30 days were transferred to 28 degrees C, growth resumed quickly, and at a rate virtually identical to that for unchilled cells. Similar results were found for cells maintained at 0 degrees C, and for cells of ;VFNT Cherry' and of L. hirsutum. Under certain conditions, cultures slowly doubled in fresh weight and cell volume at 8 or 9 degrees C but additional growth at 8 degrees C did not occur, nor could growth be maintained by subculture at 8 or 9 degrees C. The results are contrary to reports that cell cultures of tomato die when exposed to temperatures below 10 degrees C for 1 or 2 weeks. Our observations indicate that chilling temperatures quickly inhibit growth of tomato cells, but do not kill them.

Journal Article↗
PubMed1984

Natural and induced immunity to hepatitis B virus among the staff of a pediatric oncology center.

All employees of St. Jude Children's Research Hospital who were at risk for occupational exposure to hepatitis B virus were considered appropriate candidates for immunization when the vaccine was licensed in November 1981. Because a high prevalence of hepatitis B immunity was expected among the staff, preimmunization screening was undertaken in the belief that it would be cost effective. Of 315 candidates screened for antibody to the hepatitis B surface antigen (anti-HBs), 79 (25%) had detectable levels and 48 (15%) had titers of greater than or equal to 10 ratio units (RU). The highest rates of anti-HBs positivity were found among housekeepers (40%), nursing assistants (35%), physicians (31%), clinical laboratory workers (29%), and ward clerks (27%); nurses had the lowest rate (16%). An evaluation of potential risk factors implicated age greater than 30 years as having greatest importance. Serum samples were collected from 221 employees 3 months after their third dose of vaccine and tested for anti-HBs; 218 (98.6%) were seropositive. Eighteen employees who had detectable anti-HBs in the range of 2.1 to 9.9 RU before immunization responded well to the vaccine; the titers rose from an average of 4 RU before vaccination to an average of 313 RU 3 months after the third dose. The findings indicate that preimmunization screening of all health care workers identified as candidates for vaccination may not be necessary or economically feasible. If a screening program is undertaken, however, anti-HBs testing of only those persons greater than 30 years of age would increase the program's cost effectiveness.

Adult↗
PubMed1984

A simplified and efficient vector-primer cDNA cloning system.

A simplified, efficient, and versatile vector-primer cDNA cloning system is presented. The dimer-primer system is a modification of the method of Okayama and Berg (1982) with the following features: (i) the vector-primer molecules are more rapidly and reliably prepared by virtue of the elimination of an endonuclease digestion and the agarose gel purification step from the original method, and (ii) the final cDNA products contain polylinkers at both cDNA-vector junctions, simplifying the size analysis, subcloning, and sequencing of inserts. The system is highly efficient, yielding greater than 10(5) transformants using 1 microgram mRNA and 1 pmol of vector-primer ends, with 75% or more of the transformants having inserts. The ability of the system to produce clones of full-length or near full-length is demonstrated by the analysis of 32 ribulose-1,5-bisphosphate carboxylase small subunit cDNA clones from tomato.

Animals↗
PubMed1983

Oral drug reaction to methyldopa. Report of a case.

This case report presents and follows a rare oral drug reaction linked to the administration of methyldopa (Aldomet). The clinical appearance of oral ulcerations coincides with increased dosage of the drug. Withdrawal of methyldopa leads to gradual healing of these lesions.

Aged↗
PubMed1980

Restriction maps for twenty-one Charon vector phages.

The mapping of the sites of cleavage of nine restriction endonucleases (EcoRI, HindIII, BamHI, SalI, KpnI, SstI, BglII, XhoI, and XbaI) on 21 Charon phage vectors is described. Maps of individual subsections were obtained and then combined to assemble the complete vector maps. Calculations of maximum and minimum sizes of inserts which may be carried by the vectors using different restriction endonucleases or pairs of restriction endonucleases are presented. The regions mapped include several parts of phi 80 that had not been mapped previously.

Bacteriophage lambda↗