The photopolymerisation of methacrylic acid by colloidal semiconductors

Summary Methacrylic acid was photopolymerised using CdS and composite, CdS/HgS and CdS/TiO₂, colloidal semiconductor particles as initiators. The previously proposed photoinitiation mechanism involving the photogenerated positive hole in the valence band of the CdS colloid was confirmed by the electron scavenging action of TiO₂. The effect of pH on the course of the polymerisation was investigated and is discussed.     

Differential aluminium lactate toxicity in rabbits using either aqueous solutions or liposomal suspensions

The present paper deals with the toxic effects of aluminum lactate (Al(lact)3) in rabbits. Experimental animals were injected with 6.2 mg of Al(III) as Al(lact)3 aqueous solutions at neutral pH for 21 days. Histological examination showed different pathological lesions to the myocardial tissue, spleen, kidney and liver, with no relevant effects to lungs and CNS. On the contrary, rabbits injected with 60 micrograms of Al(III) as Al(lact)3 in a liposome suspension for 42 days showed a large infarctual zone in the spinal cord with the metal accumulation in the necrobiotic neurons. Pharmacological implications of these findings are also discussed.     

Staging of pulmonary apex tumors. Computerized tomography versus magnetic resonance

In an experiment designed to distinguish between the behavioral consequences of treatment with SCH-23390, a D1 dopamine receptor blocker, and raclopride, a D2 antagonist, rats were trained to perform a water-reinforced forelimb operant response. Response rate and the duration of each forelimb contact with the operandum were recorded. In addition, the durations of the rat's visits to the reward well were detected by a photobeam which was blocked by the rat's muzzle as it remained at the reward well. In a between-groups dosing design, separate groups of rats (11-13 rats/group) received SCH-23390 (0, 0.01, 0.02, 0.04, 0.08, 0.12 mg/kg, IP, 30 min) or raclopride (0. 0.05, 0.1, 0.2, 0.4, 0.8 mg/kg, IP, 30 min) for 21 consecutive days. Quantitative analyses indicated that for comparable amounts of operant rate reduction, raclopride had a significantly greater tendency than SCH-23390 to increase the duration of operant responses and to increase the maximum muzzle entry duration (i.e., to induce microcatalepsy). The results support the idea that at relatively low doses D2 antagonism is more likely than D1 antagonism to produce effects identified preclinically with extrapyramidal side effects.     

TGF-beta-induced apoptosis of cerebellar granule neurons is prevented by depolarization

The regulation of programmed cell death in the developing nervous system involves target-derived survival factors, afferent synaptic activity, and hormone- and cytokine-dependent signaling. Cultured immature cerebellar granule neurons die by apoptosis within several days in vitro unless maintained in depolarizing (high) concentrations of potassium (25 mM K+). Here we report that transforming growth factors (TGF)-beta1, -beta2, and -beta3 accelerate apoptosis of these neurons when maintained in physiological (low) K+ medium (5mM K+) as assessed by measures of viability, quantitative DNA fragmentation, and nuclear morphology. TGF-beta-induced apoptosis of these neurons is not blocked by CNTF and LIF, cytokines that enhance neuronal survival when applied alone, or by IGF-I, which prevents apoptosis upon potassium withdrawal. In contrast, neurons that differentiate in high K+ medium for several days in vitro acquire resistance to TGF-beta-mediated cell death. Granule neurons maintained in either low or high K+ medium produce latent, but not bioactive, TGF-beta1 and -beta2. Because neutralizing TGF-beta antibodies fail to augment survival of low K+ neurons, the cerebellar neurons are apparently unable to activate latent TGF-beta. Thus, apoptosis of low K+ neurons is not attributable to endogenous production of TGF-beta. Taken together, our data suggest that TGF-beta may limit the expansion of postmitotic neuronal precursor populations by promoting their apoptosis but may support survival of those neurons that have maturated, differentiated, and established supportive synaptic connectivity.     

Stress fracture of the sternum: an unusual injury?

Stress fracture of the sternum is a rare condition which presents as acute anterior chest pain after repetitive upper-body exercise. Two case reports are presented and it is postulated that this is an often underdiagnosed condition which should be considered in the differential diagnosis of acute chest pain in the athlete. Awareness of the injury together with meticulous clinical examination supported by good quality radiographs or isotope bone scan may lead to an increase in the diagnosis of this injury.     

Frontoethmoidal meningoencephaloceles: a review of 14 consecutive patients

Over a period of 4.5 years, 14 patients with frontoethmoidal meningoencephaloceles were treated. Most patients came from Northern Namibia. Precise delineation of all cranial abnormalities was obtained by modern imaging techniques, and specific patterns of cerebral abnormality were found. The malformation was corrected in a single stage, and significant modifications have been developed to render the procedure simpler and safer. Information from our series favors delayed neural tube closure as the primary pathogenesis of the defect and suggests a common teratogen as the most probable etiological agent. Our experience leads us to advocate early correction of even small defects.     

Cystic fibrosis: the delta F508 mutation does not lead to an exceptionally severe phenotype. A cohort study

In an attempt to ascertain a relationship between genotype and phenotype, we studied the pulmonary and nutritional status of 123 cystic fibrosis patients with known genotype at an age of 8.5-10 years. Patients represent a cohort as they are almost all those born and diagnosed in a given area and period. They were followed at a single centre using uniform diagnostic and treatment protocols. Pulmonary and nutritional status of homozygous delta 508 patients did not differ from that of compound heterozygotes or of patients with other unspecified genotypes. Pulmonary manifestations varied widely in all genotype groups. With the given number of patients, a slightly higher mortality of delta F508 homozygotes could have been coincidental. We conclude that up to the age of 8.5-10 years the severity of pulmonary lesions and nutritional deficiencies is not related to the delta F508 mutation.     

Thorn apple poisoning

A 20-year-old man presented with signs of thornapple intoxication: restlessness, disorientation, hallucinations, euphoria, and furthermore dry and red skin and symmetrical dilation of the pupils. Thornapple intoxication mimics atropine intoxication. Thorn apples (Datura stramonium) are seemingly becoming popular as a hallucinogenic drug. When the symptoms are mild gastric lavage leaving active charcoal in the stomach afterwards will suffice. In case of severe symptoms treatment with physostigmine is indicated.