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Biomedical subjects

G M Watson

Publications and source records attributed to G M Watson.

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

Temporary prostatic stenting and androgen suppression: a new minimally invasive approach to malignant prostatic retention.

Urinary retention secondary to carcinoma of the prostate is usually treated by 'channel' transurethral resection of the prostate either performed alone or in combination with hormone manipulation. The combination of temporary prostatic stenting and androgen suppression may reduce the morbidity and mortality associated with this treatment. We report on our initial experience using the combination of a temporary prostatic stent with the oral anti-androgen Flutamide in 10 patients with urinary retention or severe bladder outflow obstruction secondary to prostatic carcinoma. Eight of the ten patients successfully voided and maintained normal voiding after stent removal. There were two treatment failures requiring prostatic resection. We believe the cost of stenting and medication is entirely justified by patient preference and clearance of hospital beds.

Aged↗
PubMed1992

Receptors for N-acetylated sugars may stimulate adenylate cyclase to sensitize and tune mechanoreceptors involved in triggering nematocyst discharge.

In fishing tentacles of sea anemones, cnidocyte/supporting cell complexes (CSCCs) trigger the discharge of nematocysts following stimulation by swimming prey of specific mechanoreceptors and chemoreceptors located on the supporting cells. Two types of mechanoreceptors have been identified: a contact-sensitive mechanoreceptor (CSM), and a vibration-sensitive mechanoreceptor (VSM). The CSMs become predisposed to initiate nematocyst discharge into static (i.e., nonvibrating) test probes in the presence of submicromolar free and conjugated N-acetylated sugars, a process referred to as sensitization. In seawater, the VSMs cause maximal discharge in response to test probes vibrating at 30, 50-55, and 75 Hz, whereas in the presence of submicromolar N-acetylated sugars the VSMs cause maximal discharge into test probes vibrating at 5, 15, 30, and 40 Hz, a process referred to as tuning. Tuning of the VSMs is accompanied by elongation of the stereocilium bundles comprising the VSMs. We report that dibutyryl cyclic-AMP sensitizes CSMs and tunes VSMs to the lower frequencies of 5, 15, 30, and 40 Hz, while cyclic-AMP has no such effects. Endogenous adenylate cyclase activity at the apical plasma membrane of the supporting cells is detectable by cytochemical methods in the presence of N-acetylated sugars but not in seawater alone. By activating adenylate cyclase with L858051, an analogue of forskolin, or by activating the stimulatory form of G proteins (Gs) with cholera toxin, CSCCs are induced to sensitize CSMs and to tune VSMs to the lower frequencies of 5, 15, 30, and 40 Hz. Caged GTP-gamma S also sensitizes CSMs but tunes VSMs to 5, 15, 30, 40, 55, 65, and 75 Hz, suggesting that VSM tuning may be regulated both by Gs and inhibitory G-proteins. Together, these results implicate cAMP as the second messenger for activated supporting cell chemoreceptors involved in sensitizing the CSMs and tuning the VSMs to lower frequencies.

Acetylglucosamine↗
PubMed1991

Leukaemia and paternal radiation exposure.

OBJECTIVE: Recently, Gardner and colleagues inferred, from a case-control study of leukaemia incidence in young people near the Sellafield nuclear facility in West Cumbria, that an increase near Sellafield was real, and was probably caused by occupational exposure of the father to ionising radiation at the Sellafield plant. The intent of this paper is to dispute that attribution, and to suggest that confirmation of such an alarming and prejudicial conclusion should precede its dissemination. MATERIAL CONSIDERED: Critical comment is limited to the paper by the Gardner group presenting their results, the accompanying paper outlining their methods, a review from Mathews that provides some support for the Gardner proposal by suggesting a pathogenetic mechanism, and some observations on inherited tumours by Nomura that are quoted by Gardner et al. and Mathews in support of their beliefs. Other material quoted is from the general medical literature of the past 20 years relating to radiation biology, mutagenesis and carcinogenesis with some relevance to the Gardner contention; it is not exhaustive. MAIN RESULTS: Statistical arguments suggest that it is almost impossible to be sure that a specific leukaemia "cluster", such as that near Sellafield, is not a chance finding. The study by Gardner et al. provides only weak statistical evidence for an association between leukaemia in children and parental occupational radiation exposure at Sellafield. The postulate of a causal relation between parental exposure at Sellafield and leukaemia in progeny is incompatible with what is known of the role of genetic mechanisms in leukaemia, with current views on the quantitative relation between radiation dose and mutagenetic effect, and with observations on the children of people exposed to radiation by the nuclear bombs used in Japan in 1945. CONCLUSIONS: The suggestion that occupational exposure to ionising radiation of a father may be responsible for an increased risk of leukaemia in his children cannot be substantiated. It would be proper to seek confirmation from other groups of occupationally exposed persons before undertaking precipitous, and inevitably disturbing, action to remedy the supposed problem.

Adult↗
PubMed1991

Use of biofeedback in treatment of psychogenic voiding dysfunction.

A young man with psychologic problems and a long history of social inadequacy presented with voiding dysfunction. Videocystometrography revealed a normal filling phase and normal initiation of voiding interrupted by considerable straining by the patient and marked sphincter electromyographic (EMG) activity. Temporary amelioration was achieved by infiltration of the sphincter with lignocaine hydrochloride and by biofeedback therapy. In such cases optimal results are expected from long-term behavioral therapy.

Adult↗
PubMed1990

Concurrent validity of the Test of Nonverbal Intelligence with referred suburban and Canadian native children.

The relationship between the Test of Nonverbal Intelligence (TONI) and the WISC-R was investigated for cultural differences. The samples consisted of 30 suburban and 22 Native children who were referred for learning difficulties. The results indicated the suburban group was higher than the Native group on Verbal IQ, but not Performance IQ, Full Scale IQ, or the TONI Quotient. The correlation coefficient between the TONI Quotient and PIQ was as expected in the Native group, but unexpectedly low in the suburban group. Implications of these findings for the testing of both referred majority and Native group members are discussed.

Child↗
PubMed1990

Identification and characterization of a GroEL homologue in Rhodobacter sphaeroides.

A protein closely related to the Escherichia coli GroEL protein has been isolated from Rhodobacter sphaeroides. Native and SDS-polyacrylamide gel electrophoresis of this protein have shown that it is present in the cell as a multimeric complex of Mr 670,000 which is composed of a monomer of Mr 58,000. Antisera raised against the Mr 58,000 polypeptide have been shown to cross-react with GroEL and the alpha subunit of the pea plastid chaperonin. The N-terminal amino acid sequence of the Mr 58,000 polypeptide is identical to that of GroEL at 15 of 19 residues and is also closely related to the alpha subunit of the pea plastid chaperonin, though less so to the beta subunit.

Amino Acid Sequence↗
PubMed1989

Cnidocyte mechanoreceptors are tuned to the movements of swimming prey by chemoreceptors.

Cnidocytes, the stinging cells of cnidarians, discharge nematocysts in response to physical contact accompanied by the stimulation of specific chemoreceptors. Cnidocytes in fishing tentacles of a sea anemone are now found to discharge nematocysts preferentially into targets vibrating at 30, 55, and 65 to 75 hertz. Moreover, in the presence of submicromolar concentrations of known chemosensitizers, such as N-acetylated sugars and mucin, these optima shift to 5, 15, 30, and 40 hertz, frequencies that correspond to the movements of swimming prey. Hence, chemoreceptors for these substances tune cnidocyte mechanoreceptors to frequencies that match the movements of the prey.

Animals↗
PubMed1989

Acoustic and plasma guided lasertripsy (APGL) of urinary calculi.

The feasibility of using pulsed laser generated acoustic and plasma optical emission signals to monitor laser fragmentation of urinary stones was studied in vitro. A flashlamp pumped tunable dye laser operating at a wavelength of 504 nm. (coumarin green) was used as the laser source. Acoustic signals were recorded with a hydrophone which has a useful frequency response of up to 350 KHz. Plasma optical emissions were transmitted retrograde along the laser fiber and reflected through a beam splitter to an optical detection system consisting of a series of spectral filters (to transmit plasma radiation from 380 nm.-440 nm. and block any 504 nm. laser light) and a photomultiplier tube. Measurements of acoustic and plasma signals were taken from different urinary calculi, guidewires, catheters, blood, blood clots, bruised soft tissue and normal ureter. Signals were also obtained from stones placed in ureter of an ex vivo bovine urinary tract specimen. Results of monitoring both plasma and acoustic signals show that it is possible to determine, without direct vision, whether the laser is hitting stone, ureteral wall or lumen. Strong plasma and strong acoustic signals are produced by calculi; strong acoustic but no plasma signals suggest that the laser is hitting blood clot or bruised ureteral wall. Absent plasma and acoustic response indicate that the laser is discharging on normal ureter or in the lumen. These distinctions may allow clinical stone fragmentation without direct ureteroscopic vision.

Acoustics↗
PubMed1988

Protein phosphorylation in Bacillus thuringiensis during growth and delta-endotoxin production.

At least 14 phosphopolypeptides in which the phosphate groups were present as mono-esters were detected by pulse labelling of Bacillus thuringiensis subsp. kurstaki HD-1-Dipel with [32P]orthophosphate at different stages of growth and differentiation. Marked changes in the profile of phosphopolypeptides were observed primarily during the late exponential phase of growth. Several phosphopolypeptides co-purified with the endotoxin crystal of this subspecies and the phosphoamino acid residue of the most abundant (Mr 25,000) phosphopolypeptide was identified as phosphothreonine. Comparison of the phosphopolypeptides in endotoxin crystals from several subspecies suggested that Mr 25,000 species might be a common component.

Amino Acids↗
PubMed1985

Ultrastructure of nematocyst discharge in catch tentacles of the sea anemone Haliplanella luciae (Cnidaria: Anthozoa).

The mature nematocyst lies just beneath the cnidodyte plasma membrane. A microtubule array surrounds the nematocyst capsule just beneath the capsule tip. We propose that the array helps to hold the capsule at the cnidocyte cell surface until discharge. The undischarged capsule tip is sealed by three apical flaps, joined together along complex radial seams. The seams are filled with subunits that appear to bind the flaps together. Upon discharge, the flaps separate along the radial seams to permit thread eversion. The everted thread is lined on both sides by subunits that are stained by antimonate, indicating that they bind calcium. We suggest that, together, the subunits hold the uneverted thread in its folded and coiled configuration. Thread eversion would follow subunit uncoupling. The capsule and thread interiors of partially discharged nematocysts are stained by antimonate. In contrast, the capsule and thread interiors of fully discharged nematocysts are not stained by antimonate. Thus, nematocyst calcium might be injected into the target tissue where it is presumed to act in conjunction with nematocyst venom to promote cell death.

Animals↗
PubMed1985

Adenomatous metaplasia (nephrogenic adenoma) of urothelium. An analysis of 70 cases.

A retrospective analysis of 70 cases of adenomatous metaplasia seen in the St Peter's Hospitals over a 15-year period has been carried out. The lesions occurred at all ages (7-81 years) and in both sexes (51 males, 19 females) and were found throughout the urinary tract from pelvis to urethra. In the pelvis and ureter the finding was usually an incidental one in association with stones or chronic inflammation; ulceration was a frequent accompaniment. Most vesical and urethral lesions followed a surgical procedure months or years previously, the patients re-presenting with haematuria or irritative bladder symptoms. The endoscopic appearances varied but there was often a striking correlation between the location of the lesions and the site of previous surgery. The association of adenomatous metaplasia with ulceration and previous surgery leads us to suggest that it is merely an unusual response to wound healing and attempts to treat it by diathermy resection are, therefore, likely to meet with limited success. Cystoscopic follow-up of persistent lesions gives no reason to suppose they are pre-malignant.

Adenoma↗
PubMed1984

Does calcium contribute to the effectiveness of a coagulum for pyelolithotomy?

Adding calcium to a mixture of thrombin and fibrinogen increased the breaking strain of the resultant coagulum by 10-fold, but did not significantly reduce the length to which it could be stretched. There was no detectable change in the time taken for the coagulum to dissolve in urine. Simulation pyelolithotomies were performed on pig kidneys containing ball-bearings which represented calculi. Coagula formed with calcium were significantly more effective at retrieving the ball-bearings than coagula without calcium. It is concluded that the ideal coagulum formula should include 1 mmol of calcium.

Animals↗