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Biomedical subjects

P J Howard

Publications and source records attributed to P J Howard.

At least 19 recordsLinked to original sources
PubMed2004

DNA sequence and analysis of human chromosome 9.

Chromosome 9 is highly structurally polymorphic. It contains the largest autosomal block of heterochromatin, which is heteromorphic in 6-8% of humans, whereas pericentric inversions occur in more than 1% of the population. The finished euchromatic sequence of chromosome 9 comprises 109,044,351 base pairs and represents >99.6% of the region. Analysis of the sequence reveals many intra- and interchromosomal duplications, including segmental duplications adjacent to both the centromere and the large heterochromatic block. We have annotated 1,149 genes, including genes implicated in male-to-female sex reversal, cancer and neurodegenerative disease, and 426 pseudogenes. The chromosome contains the largest interferon gene cluster in the human genome. There is also a region of exceptionally high gene and G + C content including genes paralogous to those in the major histocompatibility complex. We have also detected recently duplicated genes that exhibit different rates of sequence divergence, presumably reflecting natural selection.

Base Composition↗
PubMed2001

The physical maps for sequencing human chromosomes 1, 6, 9, 10, 13, 20 and X.

We constructed maps for eight chromosomes (1, 6, 9, 10, 13, 20, X and (previously) 22), representing one-third of the genome, by building landmark maps, isolating bacterial clones and assembling contigs. By this approach, we could establish the long-range organization of the maps early in the project, and all contig extension, gap closure and problem-solving was simplified by containment within local regions. The maps currently represent more than 94% of the euchromatic (gene-containing) regions of these chromosomes in 176 contigs, and contain 96% of the chromosome-specific markers in the human gene map. By measuring the remaining gaps, we can assess chromosome length and coverage in sequenced clones.

Chromosomes, Human, Pair 1↗
PubMed2000

Role of mitotic control in spermatogenesis.

OBJECTIVE: To study the correlation between the incidence of sex chromosome aneuploidies in the somatic cells and spermatozoa in karyotypically normal infertile men and fertile donors. DESIGN: A prospective, phase two, controlled study. SETTING: A teaching Hospital Reproductive Medicine and Medical Genetics Units. PATIENT(S): Ten patients with idiopathic oligozoospermia and 10 sperm donors with proven fertility, all with a normal karyotype 46, XY. INTERVENTION(S): Multicolor fluorescence in situ hybridization (FISH) of peripheral blood lymphocytes and spermatozoa using a probe cocktail containing the alpha satellite DXZ1 for the X centromere, DYZ1 for the heterochromatic region of the long arm of the Y, and cosmids D21S259, D21S341, and D21S342 for Down syndrome critical region of chromosome 21. MAIN OUTCOME MEASURE(S): The incidence of chromosome X, Y, and 21 aneuploidies in peripheral lymphocytes and spermatozoa in both groups. RESULT(S): The incidence of aneuploidies related to chromosomes X, Y, and 21 were significantly higher in peripheral lymphocytes and spermatozoa of infertile men compared with donors. There was a positive correlation between the incidence of chromosome aneuploidies in the somatic cells and sperm in all men. CONCLUSION(S): These findings provide suggestive evidence for the importance of mitosis in spermatogenesis and the role of mitotic instability in unexplained oligozoospermia.

Adolescent↗
PubMed2000

Evaluation of the role of mitotic instability in karyotypically normal men with oligozoospermia.

OBJECTIVE: To estimate the incidence of sex chromosome aneuploidies in the somatic cells of karyotypically normal infertile men and fertile donors. DESIGN: A prospective, two-phase, controlled study. SETTING: Reproductive medicine and medical genetics units of a teaching hospital. PATIENT(S): Ten patients with oligozoospermia and 10 sperm donors with proved fertility, all with a normal karyotype 46 XY. INTERVENTION(S): Multicolor fluorescence in situ hybridization (FISH) of peripheral blood lymphocytes using a probe cocktail containing the alpha satellites DXZ1 for the X centromere and DYZ1 for the heterochromatic region of the long arm of the Y and the radiolabeled alpha satellite D18Z1 for chromosome 18. MAIN OUTCOME MEASURE(S): The incidence of sex chromosome aneuploidies in both groups. RESULT(S): A 13-fold increase in sex chromosome aneuploidies was observed in the somatic cells of infertile men with "unexplained" oligozoospermia compared to donors (P=.008). CONCLUSION(S): These findings provide suggestive evidence for the existence of an inherent mitotic instability in men with unexplained oligozoospermia.

Adult↗
PubMed1998

Renal colic during pregnancy: a case for conservative treatment.

PURPOSE: We defined the merits of early evaluation and conservative treatment of pregnant patients admitted with renal colic. MATERIALS AND METHODS: We retrospectively evaluated 72 pregnancies in 70 patients who were hospitalized with the diagnosis of renal colic between 1984 and 1995. Urinalysis was performed in every case. Ultrasound was the primary diagnostic test in 65 patients. The patients were followed for 2 weeks to 3 months after delivery (mean 21 days). RESULTS: Mean patient age at presentation was 27.4 years. The majority of patients were multiparous (47 of 70) and presented in the third trimester (44 of 70). Microscopic urinalysis was not helpful in identifying stone disease in pregnant patients. The sensitivity of ultrasound for the diagnosis of renal calculi was 95.2%. Watchful conservative nonsurgical treatment resulted in spontaneous passage of stones in 64.3% of cases. Of the 19 pregnancies in which intervention was necessary cystoscopy and Double-J* silicone stent placement were done in 15, and ureteroscopy and stone basketing were done in 4. Two patients, who presented with pyelonephritis and premature ruptured membranes had fetal loss. Long-term antibiotic prophylaxis was maintained in all stented and bacteriuric patients. CONCLUSIONS: Renal colic in pregnant patients can be complicated by pyelonephritis and premature labor, especially if misdiagnosed or inadequately treated. Ultrasound is a safe and sensitive diagnostic test. Approximately two-thirds of renal calculi will pass spontaneously. For those who require intervention, placement of a Double-J stent is a safe and effective option.

Adult↗
PubMed1997

Physical localisation of the breakpoints of a constitutional translocation t(5;6)(q21;q21) in a child with bilateral Wilms' tumour.

A 6 month old boy presented with bilateral Wilms' tumour. Cytogenetic analysis of the lymphocytes from the patient showed a de novo balanced translocation t(5;6)(q21;q21), which was also present in the tumour material as the sole cytogenetic abnormality. To facilitate the identification of the translocation breakpoints, we have established a lymphoblastoid cell line (MA214L) from the patient which maintains the translocation in culture. We have used Genethon microsatellite markers as sequence tagged sites (STSs) to isolate yeast artificial chromosome (YAC) clones to 5q and 6q from human genomic libraries. Using fluorescence in situ hybridisation (FISH) on metaphase preparations of MA214L, we have physically defined the translocation breakpoints between YAC clones on each chromosome arm. The genetic distance separating the flanking YACs on 6q21 is 3 cM, while that on 5q21 is 4 cM. To date this is the first report of these chromosomal regions being implicated in Wilms' tumourigenesis.

Chromosome Fragility↗
PubMed1997

Histopathology and molecular cytogenetics of a corneal opacity associated with the trisomy 8 mosaic syndrome (46,XY/47,XY, +8).

The trisomy 8 mosaic syndrome (Tr8MS), karyotype 46,XY/47,XY, +8, is a rare multisystem disorder that may be associated with corneal opacity. We report the case of a dysmorphic infant with multiple congenital abnormalities referred to our unit with a congenital corneal opacity. Subsequent chromosomal analysis of peripheral leucocytes demonstrated constitutional Tr8MS. At 4 years of age, lamellar keratoplasty was performed. Histological examination confirmed the lesion to be consistent with a corneal choristoma. Cytogenetic studies using in situ hybridisation techniques showed the presence of trisomic cells in cell culture derived from the tissue in higher proportion (92%) than in the blood (44%). Amplification of the c-myc oncogene on chromosome-8 could not be detected in cells cultured from the corneal lesion. Although not proof, these findings lend support to the concept of the corneal lesion representing a focus of viable trisomic cells rather than an inflammatory response to a nidus of effete cells.

Abnormalities, Multiple↗
PubMed1992

Multiple cytogenetic aberrations in squamous cell carcinomas of the head and neck.

Chromosomal abnormalities in short term cultures have been investigated in 10 squamous cell carcinomas of the head and neck. Of these tumours, three demonstrated clonal chromosomal abnormalities, two showed random abnormalities and 5 patients' tumours had normal karyotypes. The 5 patients with aberrant karyotypes were all from previously treated tumours, of these, 4 patients had received radiotherapy and 1 surgery. On analysis of the three clonal tumours, two were found to be polyclonal, each with five separate clones. 116 breakpoints were demonstrated from the clonal data of these tumours, and all of the chromosomes were involved, apart from number 18. In this study we found three or more breakpoints at sites 1p36, 9q32 and 11q23. 1 of the patients investigated showed a clonal abnormality involving a breakpoint at the 11q13 site, with a further 2 patients having breakpoints at 1p22--sites previously reported to have marked clustering of cytogenetic abnormalities in oral cancer patients. Only further studies will demonstrate whether the breakpoints found are of clinical significance.

Carcinoma, Squamous Cell↗
PubMed1992

Differentiation of Listeria monocytogenes, Listeria innocua, Listeria ivanovii, and Listeria seeligeri by pulsed-field gel electrophoresis.

Clamped homogeneous electric field analysis of Listeria DNA with ApaI, AscI, SmaI, or NotI revealed species- and serotype-specific differences in genomic fingerprints. Clamped homogeneous electric field analysis may prove useful, therefore, in epidemiologic studies. Also, the summation of individually sized AscI fragments of genomic DNA from L. monocytogenes serotype 4b 101M and Scott A indicated genome lengths of 2,925 and 3,046 kb, respectively.

DNA Fingerprinting↗
PubMed1992

Five year prospective study of the incidence, clinical features, and diagnosis of achalasia in Edinburgh.

With the increasing availability of manometry, patients with achalasia are often referred at an early stage when they lack the classic features of established disease. A prospective five year study of the presenting features of untreated achalasia referred to our department was undertaken. Twenty men and 18 women presented throughout adult life, with a mean age at the time of diagnosis of 44 years (range 17 to 76 years). The presenting symptoms were dysphagia: for solids (100%) and for liquids (97%), chest pain (74%), and weight loss (60%). Endoscopy was reported as normal in 15 patients and achalasia was suggested in only 21 of 33 barium examinations. Fourteen had been treated for gastrooesophageal reflux but none had been misdiagnosed as having cardiac or psychiatric disease. The annual incidence of achalasia in the Lothian region is 0.8/100,000 of population. Persistent dysphagia is the cardinal symptom of achalasia which presents throughout adult life. Nevertheless, recent onset achalasia is often misdiagnosed as gastrooesophageal reflux disease. Because endoscopy is frequently normal and the diagnosis is often not made by radiology, manometric investigation is necessary if the condition is to be recognised and treated at an early stage.

Adolescent↗
PubMed1991

Arterial washin of halothane and isoflurane in young and elderly adult patients.

We have studied the effect of age on washin of isoflurane and halothane by comparing end-tidal (PE') and arterial (Pa) partial pressures of the agents in young (18-32 yr) and elderly (63-82 yr) healthy patients for 20 min after introduction of the agents, before surgery. PE' was measured by infra-red analysis and Pa by gas chromatography. Washin of isoflurane occurred at the same rate in the young and elderly, with no significant difference between young and elderly in PE' or Pa as proportions of the inspired partial pressure (PI). After 20 min of isoflurane administration, mean Pa/PI in the young was 0.57 (95% confidence limit (CL) 0.53-0.62) and 0.55 in the elderly (95% CL 0.51-0.59). Washin of halothane was slower in the elderly than in the young, with Pa/PI significantly less in the elderly from 10 min after introduction of halothane. The difference between age groups, however, was small: mean Pa/PI after 20 min of halothane administration 0.45 (95% CL 0.41-0.49) in the young and 0.38 (95% CL 0.35-0.41) in the elderly. Washin of isoflurane was significantly faster than that of halothane in both young and elderly subjects. For isoflurane, the PE'-Pa gradient was small relative to Pa and did not differ significantly between young and elderly. For halothane, PE'-Pa in the young did not differ significantly from that for isoflurane. In the elderly, PE'-Pa for halothane was significantly greater than in the young and than PE'-Pa for isoflurane.

Adolescent↗
PubMed1991

Systematic comparison of conventional oesophageal manometry with oesophageal motility while eating bread.

Conventional oesophageal manometry is seldom accompanied by symptoms and may indeed be normal in patients with a history of dysphagia. We have recently shown that oesophageal manometry during eating may be helpful in the evaluation of patients with dysphagia but there has been little systematic comparison of fed oesophageal motor patterns with conventional clinical manometry. Oesophageal manometry in response to water swallows and during eating was therefore examined in 58 consecutive patients who had been referred for clinical oesophageal function studies. The patients were divided into three groups according to the percentage of peristaltic activity during conventional manometry: group 1 (n = 21) had 100% peristalsis; group 2 (n = 29) had 1-99% peristalsis and group 3 (n = 8) were aperistaltic. All the patients in group 3 had achalasia and remained aperistaltic during eating, however, was less than with water swallows in both group 1 (53% compared with 100%) and group 2 (49% compared with 82.3%) patients. Synchronous contractions and non-conducted swallows were correspondingly increased during eating. Although there was a significant correlation between the amplitude of peristaltic contractions with water and bread in groups 1 and 2, mean peristaltic amplitudes were less with bread than with water swallows. The data show that there are substantial differences in the distal oesophageal motility patterns produced by water swallows and by eating. Conventional manometry with water swallows does not allow prediction of the fed oesophageal motility pattern, except in patients with achalasia.

Bread↗
PubMed1991

Gall bladder emptying patterns in response to a normal meal in healthy subjects and patients with gall stones: ultrasound study.

In this study gall bladder emptying patterns in response to a solid meal were studied using ultrasound. A similar triphasic pattern was seen in eight healthy control subjects and eight patients with gall stones, with 'early' and 'late' net emptying phases separated by a period of net refilling with peak postprandial gall bladder volumes occurring at (mean (SD)) 33.1 (17.9) minutes and 27.4 (18.8) minutes in control subjects and patients, respectively. A phase of slower net emptying followed, which was complete at 146 (33) minutes in control subjects and 125 (33) minutes in the gall stone patients (not significant). Superimposed upon this overall triphasic pattern, postprandial gall bladder emptying was punctuated by repeated short lived episodes of filling and emptying. The mean (SD) estimated postprandial bile outputs were 0.83 (0.34) ml/min in four control subjects and 1.2 (1.1) ml/min in seven patients with gall stones. We propose a 'washout' model to reconcile this large turnover of bile with the concentrating and storage functions of the gall bladder and predict that the extent rather than the rate of gall bladder emptying is important in determining stasis of bile in the gall bladder.

Adult↗