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Biomedical subjects

B John

Publications and source records attributed to B John.

At least 19 recordsLinked to original sources
PubMed1991

Mitomycin-C/5-FU and radiation therapy for locally advanced uterine cervical cancer.

To assess the feasibility and effectiveness of combined therapy on locally advanced cervical cancer, we entered 38 patients into a study. The patients were treated with mitomycin-C (10 mg/m2) on Days 1 and 30 and 5-FU (1000 mg/m2) on Days 1 to 4 and Days 30 to 33. In 5 weeks 4500-5000 cGy was given concurrently, followed by radioactive implants. Twenty-six patients had an early-stage disease (IB-IIB) and twelve had a late-stage disease (IIIB-IVA). Eighty-seven percent (33/38) of the patients had a tumor measuring 5 cm or more. The other 5 patients with a tumor size under 5 cm had biopsy-proven positive pelvic nodes; 2 of these 5 patients had a pretherapy hysterectomy. Tumor response, complete (CR) vs partial (PR), was assessed in 36 patients 3 months after completion of therapy. A CR was noted in 80% (29/36) of the patients. The PR status conferred a detrimental effect on the pelvic disease control (PDC), disease-free survival (DFS), and survival (S) while late stage correlated with the development of distant metastases (DM) and a poor DFS. PDC was obtained in 93% (27/29) of the patients who had a CR, as compared to only 43% (3/7) of those with a PR (P = 0.0228). The DFS and S rates were 59 and 77% for patients with a CR and 21 and 19% for those with a PR; respective P values were 0.0340 and 0.0002. Eleven percent (3/26) of the patients with an early stage developed DM, as compared to 50% (6/12) of those with late stage, (P = 0.0016). The DFS rates were 80 and 37% for patients with an early and late stage, respectively (P = 0.0141). Four patients developed transient neutropenia and one had transient thrombocytopenia. The second dose of mitomycin-C was omitted in 4 patients due to persistent neutropenia in 3 and to transfusion-related hepatitis in 1. Two percent (5/21) of the patients who had a staging laparotomy developed wound dehiscence. Three patients developed non-cancer-related small bowel obstruction requiring surgery. We concluded that this combined regimen was well tolerated. Although it was effective in controlling the cancer in the pelvis, this regimen failed to control DM in late-stage patients.

Adult↗
PubMed1988

A diverging gynecological template for radioactive interstitial/intracavitary implants of the cervix.

The Syed-Neblett perineal template has been in use at our institution since 1984. We have occasionally encountered problems in inserting the needles through the peripheral rows of the template and have seen significant convergence of the needles cephalad to the template. To solve these problems we have modified the Syed-Neblett template. In the new design, the entrance holes are closer together than in the original template, but they are angled so as to achieve a more compact design while maintaining a dose distribution close to that of the Syed-Neblett design. We have seen significantly fewer clinical problems with this design. In addition, a smaller number of needles achieve the same dose distribution; this simplifies their visualization on radiographs.

Brachytherapy↗
PubMed1987

Acute functional psychoses: treatment with zuclopenthixol dihydrochloride ('Clopixol') tablets.

An assessment of the efficacy and tolerability of zuclopenthixol dihydrochloride tablets in the treatment of acute psychotic episodes was undertaken in 63 patients in an open multi-centre study. Most patients prior to entering the study had received other neuroleptic drugs, but with inadequate effect. During the 10-week study, the dosage of zuclopenthixol dihydrochloride tablets could be adjusted to obtain optimum clinical benefit. The majority of patients received 20 to 75 mg daily (range 10 to 150 mg daily) at the start of the study and later, for most of those patients successfully treated, the dosage was 20 to 55 mg daily. Assessments before and during treatment utilized the BPRS and CGI rating scales and a check-list of side-effects. A successful response to treatment was achieved in 70% of 50 patients with schizophrenia or schizophreniform psychoses and in 69% of 13 patients with mania or hypomania. Almost half (30) of the patients studied had a successful response within 4 weeks of starting treatment and some after only 1 week of treatment. All patients but 1 had either no side-effects or side-effects not overtly affecting performance.

Acute Disease↗
PubMed1985

Equilocality of heterochromatin distribution and heterochromatin heterogeneity in acridid grasshoppers.

Comparative fluorescence studies on the chromosome of ten species of acridid grasshoppers, with varying amounts and locations of C-band positive heterochromatin, indicate that the only regions to fluoresce differentially are those that C-band. Within a given species there is a marked tendency for groups of chromosomes to accumulate heterochromatin with similar fluorescence behaviour at similar sites. This applies to all three major categories of heterochromatin - centric, interstitial and telomeric. Different sites within the same complement, however, tend to have different fluorescence properties. In particular, centric C-bands within a given species are regularly distinguishable in their behaviour from telomeric C-bands. Different species on the other hand, may show distinct forms of differential fluorescence at equilocal sites. These varying patterns of heterochromatin heterogeneity, both within and between species, indicate that whatever determines the differential response to fluorochromes has tended to operate both on an equilocal basis and in a concerted fashion. This is reinforced by the fact that structural rearrangements that lead to the relocation of centric C-bands, either within or between species, may also be accompanied by a change in fluorescence behaviour.

Animals↗
PubMed1985

[45,X/46,X,del(Yq) sex chromosome mosaicism--analysis of the phenotypic expression].

Three female patients with Turner-syndrome (sexual infantilism, short stature and somatic Turner-stigmata) have been analysed cytogenetically by means of different banding techniques. A deletion of the distal heterochromatic band Yq12 of the Y chromosome was observed in a mosaic with a 45,X-cell line, i.e. the karyotype is 45,X/46,X,del(Y)(q12). In order to get information about the phenotypic expression of the 45,X/46,X,del(Yq) mosaicism all previously published cases have been reviewed. Comparing the phenotypes of all 45,X/46,X,del(Yq) mosaic cases three different phenotype categories of sexual development can be distinguished: female individuals with sexual infantilism and Turner-stigmata, individuals with ambiguous genitals, ranging from clitoris hypertrophy of female genitals to hypospadia of males, male individuals, who are infertile (azoospermic). A comparison of the appearance of external genitals with the status of gonads of all patients revealed an unequivocal relationship between the gonad status and the resulting phenotype category. Furthermore, the role of Y-chromosomal loci determining testicular differentiation (biological function of H-Y antigen) for male development has been emphasized. The effect of the 45,X-cell line on the expression of short stature and somatic Turner-stigmata is independent of sexual development. Considering the great phenotypic variability of the 45,X/46,X,del(Yq) mosaicism it seems impossible to deduce a definitive phenotype. This problem is acute in prenatal diagnosis especially.

Adolescent↗
PubMed1985

[Fertility in the Ullrich-Turner syndrome].

We report on a 29-year old female patient with Turner's syndrome and sex chromosome mosaic 46,XX/45,X. The female patient shows a few somatic Turner-stigmata, short stature and fertility. The possibility of the development of endocrine active ovaries in women with Turner's syndrome and its consequences has been emphasized.

Adult↗
PubMed1979

Heterochromatin and satellite DNA in man: properties and prospects.

In reviewing the properties of heterochromatin and satellite DNA in man, it is clear that the human genome does not readily lend itself to experimental tests of the postulated functions for satellite DNA. Since the spectrum of known structural properties of vertebrate and invertebrate satellite DNAs are broadly overlapping, an alternative avenue is to experimentally manipulate the heterochromatin of an organism, and then evaluate the generality of the results. When this is done in Drosophila melanogaster, the one organism where such an experimental approach is indeed possible, the results provide no support for most of the popular hypotheses concerning satellite DNA function. They do, however, reveal an important effect on the meiotic system, namely that the position of crossover events can be markedly altered in the presence of heterochromatin known to be rich in satellite DNAs. This effect is not peculiar to Drosophila, since supporting data are readily available from natural situations in both mammals and grasshoppers. In all such cases, the effects are most easily discernible where the heterochromatic blocks are substantial in size, and non-centric in location, situations which do not apply in man. The human system, however, offers other potentials. The ubiquity of naturally occurring heterochromatic polymorphisms, coupled with the extreme sensitivity of the human genome to perturbation, offers some scope for assessing the possible somatic effects of alterations in the amount of satellite DNA.

Animals↗
PubMed1977

Cytogenetic components of reproductive isolation in Trimerotropis thalassica and T. occidentalis.

The grasshopper Trimerotropis thalassica (Bruner) has a diploid count of 2n=23 male (XO), 24 female (XX). The two largest autosomes pairs are regularly metacentric, a consequence of fixed pericentric inversions. The X-chromosome is also a fixed metacentric. The remaining nine pairs of autosmes are polymorphic for floating percentric inversions so that the complement consists of a mixture of telocentric and metacentric members. Trimerotropis occidentalis (Bruner) is polymorphic for comparable inversions in only two of its autosome pairs and has a telocentric X. It is however, unique among the species of the genus Trimerotropis in having only 21 chromosomes in its male diploid set in all the populations so far studied. A single male found in a mixed population of these two species at Jasper Ridge, Stanford University, was characterized by the count 2n=22 male. In both this respect of and in its phenotype it was intermediate in character, representing a natural F1 hybrid between the two species. Cytogenetic analysis of this hybrid male indicated that occidentalis is differentiated from thalassica only is respect of a single tandem translocation. This has involved two of the telocentric elements of thalassica which have fused into a single composite telocentric partly homologous with each of the smaller progenitors. Although potentially capable of forming a multiple of three, one or other of the progenitor chromosomes regularly fails to pair with the tandem product in the hybrid so that one or more univalents invariably occur. These, by lagging, prevent cytokinesis and subsequently lead to the formation of macrospermatids which inevitably produce a measure of sterility. It is argued that this sterility provides a basis of reproductive isolation.

Animals↗
PubMed1976

Myths and mechanisms of meiosis.

A comparative analysis of the meiotic secquence in a wide variety of organisms indicates there is no convincing evidence that: (1) Premeiotic pairing plays any role in the synapsis of homologues. (2) Heterochromatic association facilitates homologous pairing. (3) Chiasmata ever form within segments which are positively heteropycnotic at zygotenepachytene. (4) Localisation of chiasmata depends on prior localisation of pairing or on the occurrence of euchromatin-heterochromatin boundaries. (5) Prior association of centromeres plays any role in determing co-orientation. (6) Any form of supra-chromosomal organisation exists involving permanent association between the members of a haploid complement, and (7) Unequal progeny ratios recovered from structurally modified Drosophila complements arise as a consequence of distributive pairing.--On the other hand there is good evidence that: (1) Interlocking of bivalents can occur regularly in species with a chiasma frequency sufficiently high to regularly produce ring bivalents and in which the chiasmata are localised to the ends of the bivalent. (2) Some forms of terminal association cannot represent terminalised chiasmata. (3) U-type exchanges present at diplotene result from errors in crossing over. (4) Pairing and chiasma formation are not necessary for coorientation, and (5) at least some types of elastic constrictions present at first metaphase represent extended nucleolar organisers.

Animals↗
PubMed1976

Case report: lithium in reactive depression.

A 25-year old woman suffering from severe reactive depression was treated with lithium carbonate 1500 mg per day. On this regime she showed a very good improvement, and after 4 weeks of in-patient treatment was free of symptoms. At 6-months' follow-up there was no recurrence of symptoms; her serum lithium levels were within therapeutic range (0.6 to 1.2 mEq/1).

Adjustment Disorders↗
PubMed1975

The cytogenetic structure of Tasmanian populations of Phaulacridium vittatum.

In 8 out of 20 Tasmanian populations of Phaulacridium vittatum from 0.3-11.0 percent of the males carried a single supernumerary chromosome. In such males the X and B univalents are both heteropycnotic at first prophase of male meiosis and associate with another in a non-homolgous manner in about two-thirds of the diplotene cells examined. In all 56 B-containing individuals studied, however, these associations lapse by first metaphase and the X and the B move at random with respect to one another at first anaphase. The supernumerary in this species is stable and only 5 of the 56 individuals with supernumeraries showed evidence of B-chromosome non-disjunction in the pre-meiotic mitoses. Since there was no other evidence for the loss or gain of supernumeraries in the male line it is clear that B-transmission is regular in the males of this species. There were significant differences between population with respect to mean cell chiasma frequency but there was no significant effect of the B-chromosome on this metric. Additionally a comparison of mean cell chiasma frequency in follicles with and without supernumeraries from a mosaic individual shows no significant difference.

Animals↗
PubMed1975

Causes and consequences of Robertsonian exchange.

At least two types of Robertsonian exchange are now known in the acrocentric chromosomes of man. Both types involve breakage in the arms adjacent to the centromere. Evidence is presented for a third type of exchange, one involving breakage within the centromere itself, in the grasshopper Percassa rugifrons. In this species, which is regularly homozygous for a single fusion metacentric, the eighteen rod autosomes have small but pronounced granules at the centric end of the chromosome. When C-banded these granules show differential Giemsa staining and appear to represent centromeric chromomeres; these chromomeres are lacking in the metacentric fusion product. Equivalent fusions may have occurred in some mammal species too and possible examples of this are discussed in sheep and mice. The Percassa fusion has led to a modification in both the frequency and the distribution of chiasmata as judged by a comparison of these properties in the metacentric relative to the two next smallest rod equivalents. Comparable modifications are known to occur in other naturally occurring fusions but these changes are certainly not automatic consequences of fusion since they are not shown in at least some newly produced fusion mutants.

Animals↗