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Biomedical subjects

G Wilson

Publications and source records attributed to G Wilson.

At least 37 records · Page 2Linked to original sources
PubMed1997

Clonal stability in late-relapsing childhood lymphoblastic leukaemia.

We report stability of a clonal immunoglobulin heavy chain (IgH) gene rearrangement in a case of childhood acute lymphoblastic leukaemia (ALL) relapsing 17 years after completion of first-line therapy. Clonal stability was shown by polymerase chain reaction amplification of the hypervariable CDRIII region of IgH gene. Identically sized products from the original diagnostic and the second presentation samples were obtained and direct sequencing confirmed complete sequence homology. Absence of clonal evolution together with recent reports of persistent minimal residual disease in patients in long-term complete remission, suggests that 'cure' of childhood ALL may be critically dependent on effective immune surveillance to keep such disease below clinically significant levels.

Adult↗
PubMed1997

Mechanisms of action of anti-GM1 and anti-GQ1b ganglioside antibodies in Guillain-Barré syndrome.

Anti-GM1 and anti-GQ1b ganglioside antibodies are found in association with acute and chronic peripheral neuropathies, including Guillain-Barré syndrome. They are believed to arise as a result of molecular mimicry with immunogenic microbial polysaccharides. Although anti-ganglioside antibodies are suspected to play a causal role in neuropathy pathogenesis, the details of this have yet to be proven. The approach in this laboratory to solving this issue has been to generate anti-GM1 and anti-GQ1b monoclonal antibodies from peripheral blood lymphocytes of affected patients and to study their immunolocalization in peripheral nerve and their electrophysiologic effects in animal models in which peripheral nerve sites are exposed to anti-ganglioside antibodies. These data show that anti-ganglioside antibody-reactive epitopes are widely distributed in peripheral nerve and can cause electrophysiologic abnormalities in a variety of model systems; thus, these data support the view that anti-ganglioside antibody-reactive epitopes may directly contribute to neuropathy pathogenesis.

Animals↗
PubMed1997

Size of cells collected from normal human subjects using contact lens cytology.

This paper describes how a soft contact lens can be used to harvest cells from the surface of the corneal epithelium. The procedure is called contact lens cytology (CLC). Cells were removed from a soft contact lens by irrigation and stained with acridine orange. Two methods for the measurement of cell size are described. First, cell size was measured using a computer-assisted technique, which calculated the area of the cell from its outline. The second method was simpler in that it required only a single measurement of the longest dimension of the cell (the cell length). To test the validity of this simpler method, cell area was compared with cell length in 185 cells. The resulting correlation (r = 0.92) suggests that the size of shed cells can be described adequately using cell length in place of the more time-consuming measurement of cell area. A mathematical relation can be used to convert cell length to cell area so that results from experimenters using different measures of size can be compared. When a large pool of cells collected by CLC was divided into four aliquots and cell length measured by two observers on two different days, there were no significant differences between observers or days. Thus, the technique does not depend on one observer, and it is unaffected by a 24-h delay in measurement. Cells were harvested from the corneal epithelium of normal human subjects. The number of cells collected from any single removal of the contact lens had a range of 10 to 175 cells, and a mean of 66.8 +/- 40.4 (N = 46). Cell length was measured and plotted as frequency histograms for both eyes of each subject. The range in cell length was from 10 to 80 microns. The mean cell length for individual subjects had a low of 26.5 +/- 9.0 microns and a high of 44.2 +/- 10.2 microns, with a grand mean for all right eyes of 36.0 +/- 5.1 microns, and a grand mean for all left eyes of 34.6 +/- 5.2 microns. The mean for all eyes was 35.3 +/- 5.1 microns. Composite histograms were created with the combined data from the 23 right eyes (N = 1310 cells), and the 23 left eyes (N = 1765 cells). Individual histograms and the composite histograms were not normally distributed. Peaks in the distributions suggest the presence of different subpopulations of cells, lending support to the hypothesis that there is more than one mechanism for cell shedding.

Adult↗
PubMed1997

The effect of a shear force on the cell shedding rate of the corneal epithelium.

PURPOSE: During blinking the lids apply a shear force to the corneal epithelium. The aim of this study was to determine if a shear force applied to the epithelial surface increases the rate at which cells shed. METHODS: The shedding rate was studied in perfused whole rabbit eyes, and the effect of a shear force examined by exposing the corneas to a stirred solution. Control corneas were exposed to a static solution. The shedding rate and size of shed cells were measured, and the number of terminally differentiated cells on the corneal surface determined after 6 h of perfusion using ethidium bromide. RESULTS: Compared with controls, the shear force increased the cell shedding rate from the corneal surface significantly (p < 0.01, paired t-test). The increase was due to small cells with a longest dimension less than 25 microm. The number of terminally differentiated cells on the epithelial surface did not increase. CONCLUSION: Because of the decrease in size, and the change in appearance of shedding cells, it is proposed that the increase in cell shedding rate was due to an increase in the number of apoptotic cells, and not to an increase in terminally differentiated cells. It is suggested that in the human eye, under adverse conditions, shear forces due to blinking may play a role in creating apoptotic cells.

Animals↗
PubMed1997

Rapid recovery of spermatogenesis after mitoxantrone, vincristine, vinblastine, and prednisone chemotherapy for Hodgkin's disease.

PURPOSE: Because the effects of mitoxantrone on human male fertility were unknown, we determined prospectively the effects of three courses of mitoxantrone (Novantrone), vincristine (Oncovin), vinblastine, prednisone (NOVP) chemotherapy on the potential for fertility of men with Hodgkin's disease (HD). PATIENTS AND METHODS: Semen analyses were performed on 58 patients with stages I-III HD before, during, and after chemotherapy and after the sperm count recovered from the effects of abdominal radiotherapy that was given after chemotherapy. RESULTS: Before the initiation of treatment, 84% of the patients were normospermic. Sperm counts declined significantly within 1 month after the start of NOVP chemotherapy. In the month after chemotherapy, 38% of patients were azoospermic, 52% had counts < 1 million/ mL, and 10% had counts between 1 and 3 million/mL. Between 2.6 and 4.5 months after the completion of chemotherapy, sperm counts recovered rapidly to normospermic levels in 63% of patients. In the remaining patients who were followed up for at least 1 year after standard upper abdominal radiotherapy, counts also recovered to normospermic levels. CONCLUSION: NOVP chemotherapy, like most other regimens, produced marked temporary effects or spermatogenesis. However, sperm production recovered very rapidly, within 3 to 4 months after the end of NOVP chemotherapy. This pattern was caused by killing differentiating spermatogenic cells, but there was little cytotoxicity or inhibition of stem cells from mitoxantrone or the other drugs. After the combination of NOVP plus abdominal radiotherapy, sperm counts and motility were restored in most patients to pretreatment levels, which were compatible with normal fertility.

Adult↗
PubMed1997

Radiation-induced cell death in the mouse testis: relationship to apoptosis.

The killing of male germ cells by radiation and other toxicants has recently been attributed to apoptosis, but a critical evaluation of the presence of the different features of apoptosis has not been performed. In this study, mouse testes exposed to radiation were examined by light microscopy, electron microscopy and terminal transferase-mediated end labeling (TUNEL) to determine whether the cells were apoptotic according to several criteria. Testes were irradiated with single doses of gamma rays of up to 5 Gy. Although the maximum response was produced by 5 Gy, even 0.5 Gy induced marked changes. The numbers of abnormal spermatogonia reached a peak 12 h after irradiation and then declined, and the total number of spermatogonia began to decline at 12 h. These changes were most prominent among the B spermatogonia and early preleptotene spermatocytes. When examined by both light and electron microscopy, the majority of the abnormal spermatogonia showed condensation of nuclear chromatin and some showed features similar to necrosis, but the typical morphological characteristics of apoptosis, margination of chromatin and nuclear fragmentation, were rare. Many of the abnormal spermatogonia were TUNEL-positive, with the maximum number occurring at 12 h after irradiation. Although the morphological features of radiation-induced spermatogonial degeneration were not typical of apoptosis, the TUNEL staining, the rapid onset of degeneration and the sensitivity to low doses suggest that the mechanism of radiation-induced spermatogonial degeneration is closely related to apoptosis.

Animals↗
PubMed1997

[A dilemma--public health care].

The financing of personal health care services has become the crucible to test elected governments in the 21st century. Governments are caught between slow economic growth, lower personal income for most workers, and the clamour of health care for more money. The Western world with an aging population, marginal employment and rising unemployment, does not appear to have the capacity to pay for all that science and technology can produce and the public wants. Neither private nor public financing seem to have developed the machinery to identify need, and to balance demand with national economic output. I wish to suggest, that although the countries in the industrialised world have travelled different routes we have arrived at the same place. The art and science of medicine coupled with the human quest for health may simply exceed our productive capacity. The organisation and financing of twenty-First Century science and technology is nearly dysfunctional, bound by Nineteenth Century values, traditions and custom, as we face the next century. This may be the question.

Cost Control↗
PubMed1997

Surgery for lung cancer: age alone is not a contraindication.

A retrospective analysis of the clinical features, operative procedures, postoperative complications and subsequent survival of 70 (50 male) elderly patients undergoing surgery for lung cancer compared with 74 (53 male) younger patients treated at the same hospital during the same period was performed, to determine if elderly people with lung cancer are less likely to benefit from and/or tolerate surgery. The elderly group had to wait longer for operation (p = 0.001) and were more likely to have pre-existing disease (p = 0.019). In contrast, they had fewer recognised postoperative complications (p = 0.032) and there was no difference between the two groups in perioperative mortality and subsequent survival. Surgical treatment of localised lung cancer represents the best chance for cure and this study suggests that age should not be a consideration in the decision to operate or not. The patient's general state of health should be assessed and management decisions based on individual status rather than on age.

Adult↗
PubMed1996

Regulation of the initiation of coronavirus JHM infection in primary oligodendrocytes and L-2 fibroblasts.

Upon maturation, primary rat oligodendrocytes become resistant to coronavirus JHM (JHMV) infection at an early stage. Involvement of cAMP-dependent protein kinase (PK) in the regulation of oligodendrocyte differentiation has been established (S. Beushausen et al. (1987). J. Virol. 61, 3795-3803). An inducer which accelerates maturation, dibutyryl cyclic AMP (dbcAMP) also upregulates the expression of the regulatory subunit, R1 of PK1. Since (i) early block preventing infection of mature oligodendrocytes can be bypassed when transfection with genomic RNA is used and (ii) inhibitors of PKs counteract the dbcAMP effect, so as to alleviate the inhibition of JHMV, enhanced expression of R1 appeared to be connected with virus restriction. This idea was confirmed following upregulation of the R1 gene in fully permissive L-2 cells. There was a connection between an effect due to R1 and dephosphorylation of the nucleocapsid protein N by an endosomal phosphoprotein phosphatase (PPPase) having the properties of types 1 or 2A enzyme which occurs during penetration of inoculum virions. An inhibition in vitro (cell free) of N dephosphorylation by R1 together with evidence that in vivo (cell culture) overexpression of R1 inhibited the endosomal PPPase as well as replication of JHMV supports the hypothesis that uncoating of the JHMV inoculum occurs after dephosphorylation, a step obligatory for dissociation of the N protein from the genome. Thus inhibition by R prevents uncoating and thereby interferes with the commencement of replication. These observations intimate the existence of a novel mechanism controlling a virus infection of specific cell target(s) undergoing a process of differentiation and maturation in the central nervous system.

Animals↗
PubMed1996

Residual structure in unfolded proteins revealed by Raman optical activity.

Because of its ability to probe directly the chiral elements of the peptide backbone, together with the very short time scale of the scattering process, vibrational Raman optical activity (ROA) can provide new information on structure in non-native states of proteins. Here we report ROA studies of hen egg white lysozyme and bovine ribonuclease A in unfolded denatured states, prepared by reducing all the disulfide bonds. ROA spectra of unfolded lysozyme at 45, 20, and 2 degrees C, and of unfolded ribonuclease A at 35 and 20 degrees C, are presented and discussed. At 45 and 20 degrees C, unfolded lysozyme appears to contain very little extended secondary structure, but at 2 degrees C there could be roughly 20% of the native amount of alpha-helix present but little beta-sheet. Unfolded ribonuclease A, on the other hand, appears to contain roughly 50% of its native-like secondary structure, including both alpha-helix and beta-sheet, at 20 degrees C; similar secondary structure persists at 35 degrees C, but the amount is reduced. The most striking result is the observation of three sharp ROA bands in the extended amide III region, originating in coupled C alpha-H and N-H deformations, which might monitor directly the dominant intrinsic propensities for residues to adopt particular phi, psi angles, averaged over the different amino acids in the mobile heteropolypeptide. Specifically, positive bands at approximately 1300 and 1314 cm-1 appear to monitor propensities for alpha-helix and beta-structure, respectively, and a negative band at approximately 1237 cm-1 appears to monitor that for the poly(L-proline) II helix. These signals are generated by individual residues clustering in the most favorable regions of the Ramachandran plot and are present even in the absence of signals from the corresponding extended secondary structures. At 45 degrees C, the 1300 and 1314 cm-1 ROA bands of unfolded lysozyme coalesce into a single sharp band from which an analysis similar to that used for exchange effects in NMR suggests a rate of approximately 2.6 x 10(12) s-1 for interconversion between the individual residue conformations at this temperature.

Animals↗
PubMed1996

The native-like tertiary fold in molten globule alpha-lactalbumin appears to be controlled by a continuous phase transition.

On account of its ability to discriminate between secondary, loop and sidegroup structure and its special sensitivity to conformational mobility, vibrational Raman optical activity (ROA) has provided new insights into the complexity of order within the molten globule state from measurements on alpha-lactalbumin at pH 2.0 over the temperature range 2 to 45 degrees C. Thus while much of the secondary structure present in the native protein persists with only a small gradual decrease with increasing temperature, the tertiary backbone fold changes dramatically, being almost complete and native-like at 2 degrees C and almost completely disordered at 35 degrees C. The change of the tertiary fold with temperature is cooperative but has no latent heat, and so has the approximate characteristics of a continuous phase transition, being of the order-disorder type since it involves the interconversion of rigid, locally-ordered loop structure with disordered mobile backbone structure. This has implications for protein folding because the long-range correlations that exist in the critical region of a continuous (but not in a first-order) phase transition could resolve, in principle, the problem of how the protein finds its native-like folding pattern at the molten globule stage.

Lactalbumin↗
PubMed1996

Potential doubling time and clinical outcome in head and neck squamous cell carcinoma treated with 70 GY in 7 weeks.

PURPOSE: To study the predictive value of pretreatment potential doubling time and labeling index, as measured by flow cytometry in patients with head and neck squamous cell carcinoma treated with conventional radiotherapy. METHODS AND MATERIALS: 70 patients with a squamous cell carcinoma of the oropharynx and 4 patients with another involved head and neck site were entered in this prospective study. The duration of the S phase (TS), the labeling index (LI), and the potential doubling time (Tpot) were obtained by flow cytometry measurements of a tumor biopsy obtained after i.v. injection of 200 mg bromodeoxyuridine to the patient. The treatment consisted of 70 Gy in 7 weeks, 2 Gy per fraction and five fractions per week. RESULTS: The mean and median LI were 7.7% (standard deviation, SD: 5.0) and 6.3%, respectively. The mean and median TS were 9.3 h (SD: 3.6) and 8.3 h, respectively. The mean and median Tpot were 5.6 days (SD: 5.4) and 4.6 days, respectively. No significant relationship was found between the Tpot or LI and the tumor stage (T), nodal status (N), histological grade, and the site of the primary within the oropharynx. The only parameter significantly associated with an increased risk of local relapse was the tumor stage (p < 0.001). The mean Tpot for the group of tumors that relapsed locally was 5.3 days (SD: 3.3), compared to 6.1 days (SD: 4.08) for those who did not relapse locally (NS). Two parameters were significantly associated with a decrease in disease-free (DFS) and overall survival, namely the tumor stage (p < 0.005, and p < 0.001, respectively, for DFS and overall survival) and nodal involvement (p = 0.02 and (p < 0.005, respectively, for DFS and overall survival). The TS, LI, DNA index, and Tpot were not significantly associated with local relapse, DFS, and survival, either in the univariate or in the multivariate analysis. CONCLUSIONS: The method used to evaluate tumor cell kinetics did not provide clinically relevant kinetic parameters for this type of cancer. The classic prognostic factors (tumor stage and nodal status) were strongly associated with clinical outcome.

Bromodeoxyuridine↗
PubMed1996

A somatically mutated human antiganglioside IgM antibody that induces experimental neuropathy in mice is encoded by the variable region heavy chain gene, V1-18.

IgM paraproteins associated with autoimmune peripheral neuropathy and anti-Pr cold agglutinins react with sialic acid epitopes present on disialylated gangliosides including GD1b, GT1b, GQ1b, and GD3. A causal relationship between the paraprotein and the neuropathy has never been proven experimentally. From peripheral blood B cells of an affected patient, we have cloned a human hybridoma secreting an antidisialosyl IgM mAb, termed Ha1, that shows identical structural and functional characteristics to its serum counterpart. Variable region analysis shows Ha1 is encoded by the same VH1 family heavy chain gene, V1-18, as the only other known anti-Pr antibody sequence and is somatically mutated, suggesting that it [correction of is] arose in vivo in response to antigenic stimulation. In the rodent peripheral nervous system, Ha1 immunolocalizes to dorsal root ganglia, motor nerve terminals, muscle spindles, myelinated axons, and nodes of Ranvier. After intraperitoneal injection of affinity-purified antibody into mice for 10 d, electrophysiological recordings from the phrenic nerve-hemidiaphragm preparation demonstrated impairment of nerve excitability and a reduction in quantal release of neurotransmitter. These data unequivocally establish that an antidisialosyl antibody can exert pathophysiological effects on the peripheral nervous system and strongly support the view that the antibody contributes to the associated human disease.

Amino Acid Sequence↗
PubMed1996

Expression of prokaryotic HhaI DNA methyltransferase is transforming and lethal to NIH 3T3 cells.

In neoplastic cells, levels of DNA methyltransferase activity are often increased, and evidence is accruing to suggest an important role for this event in tumorigenesis. To evaluate this possibility further, and to investigate the contribution of increasing de novo, as opposed to maintenance, DNA methylation in mammalian cells, we expressed the bacterial HhaI methyltransferase in cultured murine fibroblasts. This enzyme is a pure de novo DNA methyltransferase that methylates the internal C in the sequence GCGC. We find that both constitutive and induced expression of the wild-type HhaI results, primarily, in lethality to the cells. However, surviving cell clones that express low levels of M. HhaI demonstrate increased tumorigenicity as assessed by soft agar cloning efficiency (8.6% for sense HhaI-transduced PA 317 cells versus 0.4% for antisense controls; 1.7% for sense HhaI-transfected NIH 3T3 cells versus 0% for a mutant HhaI control) and tumorigenicity in nude mouse heterotransplants (75% for sense HhaI-transduced PA 317 cells versus 18.5% for antisense controls). DNA isolated from the clonogenic sense HhaI clones, versus clones expressing the mutant HhaI gene, has no increase in overall CpG methylation but an average of 27% (range, 16.7-38.9) increase in methylcytosine content at GCGC sites. These findings suggest that eukaryotic cells tolerate a narrow window of increase de novo DNA methylating capacity, above which cell death occurs and within cell transformation results. Our results further emphasize the potential role of increased DNA methyltransferase activity in the evolution of cancer.

3T3 Cells↗
PubMed1996

Time-domain reflectometry studies on Halobacterium halobium and Halobacterium marismortui.

The dielectric properties of Halobacterium halobium and Halobacterium marismortui measured over the frequency range 1 MHz to 1 GHz are compared with a single-shell model for interfacial polarization. In the case of Halobacterium halobium, the model shows excellent agreement with the experimental data for reasonable values of membrane and cytoplasmic conductivity and permittivity. For Halobacterium marismortui however, an acceptable fit to the data can only be achieved by invoking a plasma membrane conductivity some three orders of magnitude larger than that of Halobacterium halobium and adding a second high-frequency dielectric dispersion. These observations confirm the findings of a previous study and are consistent with a scheme for Halobacterium marismortui involving thermodynamic compartmentalization of Na and K ions and the existence of a conductive plasma membrane.

Cell Membrane↗