Spin relaxation by transient monopolar and bipolar optical orientation.

We have used two-color time-resolved spectroscopy to measure the relaxation of electron spin polarizations in a bulk semiconductor. The circularly polarized pump beam induces a polarization either by direct excitation from the valence band, or by free-carrier (Drude) absorption when tuned to an energy below the band gap. We find that the spin relaxation time, measured with picosecond time resolution by resonant induced Faraday rotation in both cases, increases in the presence of photogenerated holes. In the case of the material chosen, n-InSb, the increase was from 14 to 38 ps.

Radionuclide therapy in the United Kingdom in 1995.

A postal survey was conducted in the UK in 1996 to determine the facilities available and the level of activity at centres where radionuclide therapy was practised in 1995. A response rate of 79% indicated that 102 centres were providing radionuclide therapy, with 339 clinicians holding ARSAC certificates, 57% of whom were clinical oncologists. There were 84 beds available for therapy and the total number of patients treated was 11,435. Patient numbers treated by disease or procedure were: haematological, 569 (5%); benign thyroid disease, 9059 (79.2%); malignant thyroid disease, 911 (8%); bone pain palliation, 425 (3.5%); radiosynovectomy, 321 (2.8%); neuroendocrine tumour therapy, 76 (0.7%); and intra-cavitary, 56 (0.5%). The total amounts of activity of individual radiopharmaceuticals administered in GBq were: 131I, 16,695; 90Y-colloid, 88; 32P, 94.6; 131I-MIBG, 646; 89Sr, 57.6; and 186Rh-HEDP, 16. Average waiting times varied from 1 to 5 weeks, with a range of 0 to 52 weeks for some therapies. Most centres had the services of a physicist available. Compared with teaching hospitals, the 61 district hospitals had fewer allocated beds, but treated almost half of all patients. The numbers of therapies undertaken were increasing at many centres and this has implications for long-term planning.

Laparoscopic pelvic lymph node dissection.

The infiltration of pelvic lymph nodes by carcinoma of the prostate or carcinoma of the bladder is an important factor in disease staging. Until now, this could be accurately assessed only by means of open surgery, an undesirable option as an investigation. Recent advances in laparoscopic instruments and camera systems have allowed the performance of laparoscopic pelvic lymph node dissection. A series of dissections in 14 patients is reported.

Laparoscopic pelvic lymph node dissection for carcinoma of the prostate and bladder.

Improvements in instruments and camera systems have allowed the development of operative techniques for laparoscopic pelvic lymph node dissection. A series of dissections in 20 patients is reported. The mean operation time was 1 h and 40 min. When the nodes appeared malignant, a node biopsy was sent for frozen section. If this was positive, the dissection went no further. In three patients it was necessary to complete the operation by open surgery. A mean number of five lymph nodes was dissected per side. After laparoscopic dissection, all patients were discharged the morning after surgery. The operation is possible without making great demands on hospital bed occupancy and the patient has a comfortable and speedy return to normal activity. Using laparoscopic techniques, node dissection becomes a more appealing option as an investigation and staging procedure.

The immunoperoxidase localization of tumour markers in ovarian cancer: the value of CEA, EMA, cytokeratin and DD9.

Primary tumours from 40 patients with epithelial ovarian cancer, treated at St Thomas's Hospital over a 10-year period, were studied for the immunocytochemical expression of the following tumour markers in formalin-fixed paraffin embedded material: carcinoembryonic antigen (CEA), epithelial membrane antigen (EMA), cytokeratin (CAM 5.2), and DD9. An indirect immunoperoxidase staining technique was used. All of the tumours were positive for EMA and CAM 5.2, and 30% of them were positive for both CEA and DD9. The absence of CEA and DD9 may be of value in differentiating between metastatic abdominal adenocarcinomas of ovarian origin and those of gastrointestinal origin, but no indication of prognosis was obtained using these epithelial markers. The strong and widespread staining of all the tumours for EMA suggests that this may be a useful marker for detecting metastatic or recurrent disease by immunoscintigraphy.

Treatment of carcinoma of the breast with high dose oral medroxyprogesterone acetate: does increased bioavailability improve the therapeutic ratio?

Medroxyprogesterone acetate (MPA) is regarded as a valuable hormonal therapy for metastatic breast cancer. The drug is manufactured by more than one pharmaceutical company, and one particular brand of oral MPA (Provera Tablets, Upjohn) has been reformulated to incorporate micronized particles, providing significantly enhanced bioavailability. The response rate and side-effect data from a pilot study, which used the old formulation Provera Tablets 100 mg at a dosage of 800 mg/day in 28 patients with recurrent breast cancer after treatment with tamoxifen, are compared with those from another study in which 59 similar patients received 800 mg/day of new formulation Provera Tablets 200 mg. Neither of these studies, conducted in the United Kingdom, has previously been published. The response rates were similar in both studies, but there were higher incidences of significant weight gain and increased blood pressure in those patients treated with the new formulation. These side effects have been noticed by other workers employing new formulation MPA at a dosage of 800 mg per day, while it has been reported that reducing the dosage to 400 mg perday is accompanied by a lower incidence of side effects, without affecting the response rate. It is concluded that the increased serum levels of MPA, made possible by the micronized product, do not favourably influence the response of metastatic breast cancer to therapy, but may be associated with a higher incidence of side effects. Reducing the dosage of the new formulation MPA to 400 mg/day may allow a more acceptable side-effect profile, without loss of therapeutic efficacy. Such a dose reduction would make this brand of MPA more cost effective.

Treatment of acromegaly by external irradiation.

Despite the place of hypophysectomy as the primary treatment in acromegaly, external radiotherapy maintains a role as a relatively slow but effective therapy for inadequately treated patients or those unsuitable for operation. Over the last 25 years our radiotherapy regimen has differed from the published series in that we give a larger dose per fraction, with fewer treatments. We have analysed the efficacy and side-effects of this regimen in 27 subjects with acromegaly. Growth hormone levels have fallen by, on average, 27% per year in the first five years, 83% of subjects achieving a basal growth hormone of less than 10 mU/l. The acute and chronic side-effects of irradiation are discussed, including the relevance of estimates of biological potency, for example the Time Dose Fraction (TDF). One patient suffered visual loss that was most likely to be secondary to the radiotherapy. We also report the histological appearances of the pituitary fossa in five subjects previously treated with radiotherapy.

Scintigraphy and treatment of medullary carcinoma of the thyroid with iodine-131 metaiodobenzylguanidine.

We report our experience using [131I]metaiodobenzylguanidine (MIBG) to image nine patients with proven medullary carcinoma of the thyroid (MCT). Positive uptake was seen in four patients, equivocal uptake in one patient, and no uptake in four patients. Data is presented to demonstrate the pharmacokinetics of [131I]MIBG in three of the patients studied. Two patients, with diarrhea and severe pain from known bone metastases and positive uptake on [131I]MIBG diagnostic scanning, subsequently received therapeutic doses of [131I]MIBG, with marked improvement in both pain and diarrhea, but no evidence of significant biochemical response. Iodine-131 MIBG uptake in patients with MCT is variable, and gives a higher false-negative rate than is found when using [131I]MIBG to image other neuroectodermally derived tumors. The therapeutic potential of [131I]MIBG in patients with MCT warrants further evaluation, in view of the symptomatic relief experienced following therapy doses in two patients with extensive disease.

Strongyloides stercoralis hyperinfection associated with cimetidine in an immunosuppressed patient: diagnosis by endoscopic biopsy.

Immunosuppression causes Strongyloides stercoralis hyperinfection, but other factors may also be involved. We report a case of S stercoralis hyperinfection in an immunosuppressed patient that followed cimetidine therapy and was diagnosed by endoscopic biopsy.