Plant systematics in the age of genomics.
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Classification↗
Biomedical subjects
K M Cameron
Publications and source records attributed to K M Cameron.
Setting air quality standards for carcinogens: an alternative to mathematical quantitative risk assessment-discussion paper.
It has been accepted in many countries that the regulation of ambient air quality should involve the use of health-based air quality standards. Setting standards for air pollutants which are genotoxic carcinogens presents difficult problems to the regulator, in that the prediction of the effects on health of low levels of exposure is suspected to be inaccurate, and is not currently amenable to either experimental or epidemiological verification. In some countries, techniques of mathematical quantitative risk assessment have been adopted to calculate acceptable levels of exposure to, or the unit risk factors for, genotoxic carcinogens. We regard these approaches as unsatisfactory. An alternative approach, based upon a number of argued premises, a strategy which identifies decision points and the cautious application of uncertainty factors, is described.
Air Pollutants↗
Setting air quality standards for carcinogens: an alternative to mathematical quantitative risk assessment--discussion paper.
1. It has been accepted in many countries that the regulation of ambient air quality should involve the use of health-based air quality standards. 2. Setting standards for air pollutants which are genotoxic carcinogens presents difficult problems to the regulator, in that the prediction of the effects on health of low levels of exposure is suspected to be inaccurate, and is not presently amenable to either experimental or epidemiological verification. 3. In some countries, techniques of Mathematical Quantitative Risk Assessment (MQRA) have been adopted to calculate acceptable levels of exposure to, or the unit risk factors for, genotoxic carcinogens. We regard these approaches as unsatisfactory. 4. An alternative approach, based upon a number of argued premises, a strategy which identifies decision points and the cautious application of uncertainty factors, is described.
Air↗
Fetal detriment used as an index of effects of diethylene glycol on Syrian hamster fetuses.
The effect of diethylene glycol (digol, diEG; specific gravity = 1.12) on the embryo was studied in the pregnant Syrian hamster at dosages from 2 1/4 to 4 ml/kg (2.52-4.48 g/kg). The hamsters were dosed by (single) intraperitoneal injection because previous experiments had indicated that oral dosing in the drinking water (and therefore possibly gavage dosing also) causes the hamsters to drink less. The digol was diluted with distilled water and injected on d 8 of pregnancy. Distilled water was used for the controls. At all dosages, fetuses from treated animals examined at autopsy on d 15 were found to be lighter than those from control animals. Abnormalities were seen at all dosages, mainly neural-tube defects (exencephaly, cranial bleb, and myelomeningocele). No neural-tube defects were observed in control animals. A dosage-related deficit in the number of live, externally nonmalformed fetuses was observed and was matched by a dosage-related increase in the number of live externally abnormal fetuses. Few dead full-term fetuses were found, but there was a dosage-related increase in the "late" resorption rate. A new summarizing measure, the fetal detriment (FD), the deficit from control expectations of live, nonmalformed litter mass per live litter, was found to be proportional to the square of the dose-rate D, the regression through the origin in this study being FD = (0.934 +/- 0.329)D2. The 50% attrition dosage, the AD50, was 2.90 ml/kg (3.25 g/kg) in the hamster, with 95% confidence interval 2.21-5.41 ml/kg (2.48-6.06 g/kg). Diethylene glycol in high dosage produces damage to the fetuses of pregnant Syrian hamsters. It is not known whether this is an indirect result of the maternal toxicity, which was observed even at the lowest dosage used, or is the effect of digol or of its metabolites on the conceptus.
Abnormalities, Drug-Induced↗
"Dr. Willi" (1882?-1972?), disciple of Jacques Joseph.
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History, 20th Century↗
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↗
Incidental carcinoma of the prostate: treatment selection by second-look TURP.
Twenty consecutive patients, aged under 70 years, with an incidentally diagnosed (TONXMO) carcinoma of the prostate were studied to determine the value of a repeat (second-look) TURP in assessing the accuracy of the estimates of tumour grade and volume following a first resection and in selecting patients for deferred or definitive treatment. In 8 of the 20 cases no tumour was present in the second specimen and in three cases the quantities were insignificant. All patients were treated expectantly and none has developed disease progression. Appreciable residual tumour was still present in nine patients, four of whom have developed local progression despite treatment (radiotherapy or stilboestrol). It is concluded that a second-look TURP adds to the accuracy of the definition of the T-category and as such is a valuable adjunct in determining appropriate therapy in such patients.
Aged↗
Carcinoma in situ in testicular biopsies from men presenting with infertility.
This study concerns 2043 male partners of infertile marriages who underwent testicular biopsy in the 28 years from 1955 to 1982. In a review of the pathological material carcinoma in situ (CIS) was diagnosed in 8 men (0.39%). Six of these men were later found to have invasive germ cell tumours; one has remained tumour-free and one is lost to follow-up. The implication of these findings in relation to the selection of patients for biopsy and the treatment of CIS when diagnosed is discussed.
Adult↗
Testicular testosterone concentration, interstitial cell density and spermatogenesis in infertile men.
The concentration of testosterone was estimated in testicular biopsies taken from infertile men under general anaesthesia and was found to vary between 0.77 and 9.87 nmol/g wet tissue (median 3.41 nmol/g). Spermatogenesis was assessed by the Johnsen scoring technique but there was no evidence of a deficiency of intratesticular testosterone being associated with dysfunction of the seminiferous tubules. Similarly, there was no direct relationship with testicular size, clinical diagnosis, or the concentration of testosterone found in peripheral plasma taken at the same time as the testicular biopsy. These negative findings were not explained by variation in the volume densities of the Leydig cells assessed in 10 biopsies selected to the representative of the range of testosterone concentrations found in entire series. A retrospective comparison between the concentration of testosterone in peripheral plasma at the time of surgery and the available preoperative levels found in 10 patients provided further evidence for the previously reported lowering of testosterone levels by general anaesthesia. It is suggested that future studies of testicular androgens should be conducted on tissue obtained under local anaesthesia in order to eliminate this effect.
Adult↗
The Doppler assessment of varicoceles and internal spermatic vein reflux in infertile men.
The Doppler technique has been used to evaluate venous reflux in the spermatic cord. Valsalva-induced reflux occurred on the left side in 83% and on the right side in 59% of 118 patients without clinical varicoceles and there was no difference in incidence between fertile and infertile men. The significance of Valsalva-induced reflux should be questioned. Greater importance should be attributed to the spontaneous venous reflux that occurred during quiet respiration in the majority of patients with varicoceles. Seven velocity waveform patterns are described and these are thought to represent increasing degrees of internal spermatic vein reflux and provide a basis on which it is possible to grade varicoceles. The Doppler grades correlated with the size of the varicocele, and with the internal spermatic vein diameter and testosterone concentrations.
Humans↗
Vesical leukoplakia.
Thirty-two patients with vesical leukoplakia have been seen in the St Peter's group of hospitals during the past 20 years. Twenty-five (78%) were men and 7 (22%) women with an average at diagnosis of 55 years. Seventeen (53%) had a history of chronic or recurrent urinary infection whilst 9 (28%) had previously developed bladder stones. Nine patients (28%) have so far developed a carcinoma of the bladder in association with the leukoplakia and, of these 4 are dead, 2 having died of metastatic disease and 2 in the immediate post-operative period. Eight of the 9 malignancies were squamous carcinomas.
Adolescent↗
Urothelial carcinoma of the kidney and ureter.
Two hundred and three patients with upper tract urothelial tumours were reviewed. Eighty had pelvicaliceal tumours, 90 ureteric tumours, and 33 multifocal tumours of both pelvis and ureter. Two hundred patients had transitional cell carcinomas and 3 had squamous cell carcinomas. The overall corrected 5-year and 10-year survival rates were 59.7% and 41.1% respectively. Widespread multifocal occurrence poor differentiation, penetration of the muscle coat and conservative resection of tumours predisposed to a poorer prognosis.
Adult↗
Steroid treatment of male subfertility caused by antisperm antibodies.
47 subfertile men with significant titres of antisperm antibodies were treated with one of two steroid regimens. The results were assessed by changes in sperm-counts and in serum antibody titres and by subsequent pregnancies. 15 oligozoospermic men were treated with prednisone 5 mg three times a day for 3--12 months. Sperm-counts became normal in 10 men and 4 of their wives became pregnant. 14 men with normal sperm-counts received the same treatment: antibody titres fell slightly and 3 of their wives became pregnant. 18 other men with normal sperm-counts were given one or more courses of methylprednisolone 96 mg/day for 7 days. There was a more pronounced fall in antibody titres in these men, and 7 of their wives became pregnant. Testicular biopsies in 3 men with high titres of antibodies and very low sperm-counts which became normal with prednisone showed adequate spermatogenesis; however, focal round-cell infiltration of seminiferous tubules was observed in 1 case. It is suggested that a steroid-responsive immune orchitis can occur spontaneously in man, and may contribute to the infertility of men with antisperm antibodies.
Autoantibodies↗
Idications for testicular biopsy or exploration in azoospermia.
Investigation of 311 azoospermic males has shown that the combination of estimation of testicular size and plasma FSH allows the spermatogenic function of the testes to be accurately assessed by non-invasive methods. Patients with small testes and grossly elevated levels of plasma FSH have absent, or grossly impaired spermatogenesis, and do not require surgical exploration. They should be advised with regard to adoption or artificial insemination. Patients with large testes (5 cm) or an FSH level which is not grossly elevated require operation and should undergo a surgical exploration and the possible correction of an obstructive lesion. A testicular biopsy is essential if no obstructive lesion is found as the histology of these patients may show a spermatogenic arrest.
Biopsy↗
Inverted papilloma of the lower urinary tract.
A study of 35 cases of inverted papilloma of urothelium confirms that it is a distinctive entity and typically benign. These lesions occur mainly in males, may be multiple, and are sometimes situated elsewhere than in or near the trigone, which is their characteristic site. Their precise histogenesis remains uncertain. It must be stressed that not all transitional cell tumours of inverted pattern are of this type; some will have the appearance of and behave as malignant tumours. The same diagnostic criteria of malignancy established for the more common exophytic papillary neoplasms must be applied also to the inverted papillary tumours herein described.
Adult↗
Plasma gonadotrophic hormones, testicular biopsy and seminal analysis in the men of infertile marriages.
The first step in the investigation of infertile men is to obtain 2 seminal analyses 3 days after the previous ejaculation. Clinical assessment of testicular size is an unreliable means of assessing spermatogenesis and is best done by performing bilateral testicular biopsies. Azoospermic men with grossly elevated FSH levels should be advised to consider AID or adoption. Those with normal or mildly elevated FSH levels should undergo testicular exploration in an attempt to correct an obstructive lesion. Azoospermic men with subnormal FSH levels may have an isolated hormone defect which will respond to treatment with Pergonal. Different treatment programmes for oligozoospermic men depending on the results of the FSH and LH assays may lead to a more rational approach to therapy. Infertility associated with varicocele may possibly be associated with a local disturbance of "inhibin" and FSH concentrations.
Adult↗