Densitometric analysis of scans: important sources of artefact

Computed tomography (CT) research in psychiatry often relies on the assessment of minor structural changes. Recently, it has come to encompass changes in regional brain X-ray absorption density. The artefacts prone to be encountered in density measurements are reviewed, and illustrated by a series of studies carried out using a CT 1010 scanner. They are shown to be more important than hitherto assumed in the interpretation of CT scan research.     

Brain slices in radioligand binding assays: Quantification of opiate, benzodiazepines and beta-adrenergic ([H] CGP-12177) receptors

1. We have characterized and quantified specific binding of [³H]-flunitrazepam (FNZ: (benzodiazepine), [³H]-naloxone (NAL: (opiate) and [³h]cgp-12177(CGP: (beta-adrenergic) to thick slices (230–400 μm) of mouse and rat brain.

2. The binding sites are stereospecific, saturable and of high affinity. In all cases, the binding of the ligands is readily reversible and demonstrates the appropriate drug specificity.

3. In mouse brain [³H]-NAL binding is elevated by chronic treatment with naloxone (via capsules).

4. We have been unsuccessful in quantifying beta adrenoreceptors with the archetypal ligand [³H]-dihydroalprenolol (DHA). However, the use of [³H]-CGP 12177 enabled us to detect high-affinity beta adrenoreceptors in brain slices.

5. [³H]-CGP also permits the demonstration of rapid and reversible agonist-induced down-regulation (internalization) of beta binding sites.

6. We have been successful in quantifying beta adrenergic sites in single pineal glands of rat and hamster.     

Anti-idiotypic antibody with potential use as an Eimeria tenella sporozoite antigen surrogate for vaccination of chickens against coccidiosis.

Anti-idiotypic antibodies were raised in rabbits against four monoclonal antibodies with specificity for the surface antigenic determinants of Eimeria tenella sporozoites, the infective stage of the coccidial parasite. Two of the monoclonal antibodies (1073 and 15-1) transferred passive protection in chickens against E. tenella infection. The polyclonal anti-idiotype antibody preparations against protective monoclonal antibodies contained specificities for the paratope-associated idiotypes of these monoclonal antibodies, as assessed by the competitive inhibition of binding of the homologous idiotype-anti-idiotype by the sporozoite antigen. Competitive inhibition of binding of homologous idiotype-anti-idiotype by the parasite antigen was not observed when the anti-idiotype antibody preparations against monoclonal antibodies 1546 and 1096 were tested. The anti-idiotype 1073 and 15-1 antibodies functioned as surrogate antigens in vivo when used for vaccination of young chickens, as evidenced by the induction of partial protective immunity against subsequent challenge infection with virulent parasites and induction of antisporozoite antibodies. These data clearly support the view that anti-idiotypic antibodies raised against the paratope-associated idiotypes can mimic pathogen antigens and therefore can provide a possible alternative approach for the vaccination of chickens against coccidiosis.     

Familial clustering of neural tube defects and gastric cancer

A retrospective cohort study was conducted to determine whether producing an offspring with a neural tube defect (NTD) is associated with the development of unusual patterns of cancer among the parents in subsequent years. Mothers and fathers who had a child with an NTD in Upstate New York from 1945 to 1955 were followed through 1979 and compared to a control group of parents with normal offspring. Overall mortality and site-specific cancer incidence were not significantly different for case parents versus control parents, with the exception of gastric cancer, which occurred significantly more frequently in case parents. The finding of a familial association between NTDs and gastric cancer, coupled with a parallel decline in rates of these two diseases, suggests a common aetiology, perhaps related to dietary factors.     

Crossover study of the pharmacokinetics of ceftriaxone administered intravenously or intramuscularly to healthy volunteers.

The pharmacokinetics of ceftriaxone were investigated in six healthy adults. One-gram doses were administered either intramuscularly or intravenously in a crossover design study. Mean peak ceftriaxone concentrations in plasma of 79.2 and 123.2 micrograms/ml were achieved with intramuscular injection and intravenous infusion, respectively, with plasma half-lives of 5.4 and 5.8 h. The urinary recovery of ceftriaxone in the first 24 h was 37% after intravenous infusion and 25% after intramuscular injection.     

Diagnostic clinical findings of a new syndrome with night blindness, maculopathy, and enhanced S cone sensitivity

We studied eight patients who had night blindness, maculopathy (often cystoid), degenerative changes in the region of the vascular arcades, relatively mild visual field loss, and an unusual but characteristic electroretinogram. The dark-adapted electroretinogram showed no response to low-intensity stimuli that normally activate the rods, but large, slow responses to high-intensity stimuli. These large, slow waveforms persisted without change under light adaptation, and showed a striking mismatch to photopically balanced short and long wavelength stimuli (with sensitivity much greater to short than long wave-lengths). Since there is evidence from other studies that the electroretinogram and psychophysical responses represent hypersensitivity of short wavelength-sensitive (S or blue) cones, we propose that this disorder be called the enhanced S cone syndrome. There can be different degrees of severity in this syndrome, and progression appears to be slow.     

Effects of Dispersant Treatment on the Acute Aquatic Toxicity of Petroleum Hydrocarbons

The acute effects of both untreated and dispersant-treated Prudhoe Bay crude oil on the early life-stages of three marine species were investigated. Identification of which water-accommodated fraction (undispersed or chemically dispersed) was considered “more toxic” was dependent on species, time, and endpoint (and by inference, test protocol). Generally, the data showed that at roughly equivalent hydrocarbon concentrations untreated oil solutions resulted in higher initial effects (< 1 h) in mysid and topsmelt tests, whereas dispersed oil solutions elicited higher levels of larval abnormality in abalone tests and higher levels of mortality in mysid tests. While differences in test protocols existed among the species tested, topsmelt were the most sensitive species to untreated oil solutions, with mysids being most sensitive to dispersed oil solutions. Received: 1 February 1997/Accepted: 12 June 1997     

The Residency Review Committee for Radiology: its organization, function, and performance in diagnostic radiology

The accreditation process for training in radiology is managed by the Residency Review Committee for Radiology under a prescribed system. That system and the actions taken by the Committee in recent years are described. Most applications for new or continuing programs in 1975-1981 were approved. An analysis of the adverse actions of the Committee indicates the most common deficiencies were inadequate clinical experience in subspecialty areas, inadequate formal teaching, and understaffing of the clinical program. Certain trends in radiology are apparent. The numbers of programs in diagnostic and therapeutic radiology have not changed significantly over the past 5 years, whereas opportunities for training in nuclear radiology have increased greatly. The number of trainees in diagnostic radiology has increased 13% during this period; the number in radiation therapy remains unchanged. The number of women trainees in diagnostic radiology has increased from 15% to 22%, and the number of foreign graduate trainees has decreased from 19% to 11%.