Dissociation of item and order spatial memory in rats following medial prefrontal cortex lesions

In order to test whether there is a correspondence in function of prefrontal cortex in rats and humans, rats with medial prefrontal cortex lesions were tested for item and order memory for a list of items (spatial locations in a maze). Results indicate that for order memory rats with medial prefrontal cortex lesions cannot remember the order of presentation of four or eight specific spatial locations. This inability to remember order information can be seen even when animals with lesions have to remember only two spatial locations, can self-order the sequence of four or eight spatial locations, or have been presented with the same study phase on every trial. In contrast, for item memory animals with medial prefrontal cortex lesions retain the first item of the list in the variable study phase situation and remember all the items of the list in a constant study phase situation. However, there are also deficits for the last items within a list in the variable study phase situation for both win-stay and win-shift procedures. This deficit might be a function of an impairment in the utilization of appropriate temporal strategies, which normally would facilitate recognition memory in the win-stay and win-shift tasks. In general, the data suggest a partial, but not complete, dissociation of item-order memory. Furthermore, the data suggest that the medial prefrontal cortex is involved in temporal structuring of information.     

Chronic renal failure presenting as proximal muscle weakness in a child

A 13-year old boy presented with a three-year history of slowly progressive proximal muscle weakness, particularly involving the lower extremities. Chronic renal failure was uncovered in the course of his evaluation. Urologic investigation showed small and poorly functioning kidneys with a BUN of 118 mg/dL and a creatinine of 10.7 mg/dL. There were no anomalies of the proximal or distal collecting systems or history suggestive of recurrent urinary tract infection. The neurologic examination revealed proximal muscle weakness primarily of the lower extremities and especially of the proximal musculature of the pelvic girdle. Nerve conduction studies were normal. The electromyogram (EMG) showed high-voltage polyphasic potentials consistent with neurogenic muscle disease. A biopsy of the right quadriceps muscle demonstrated type II muscle fiber atrophy with histochemical staining. The patient's clinical findings, EMG studies, and muscle biopsy were not specific for either neurogenic or myopathic disease. Following a period of home peritoneal dialysis and renal transplantation, there was significant clinical improvement of the muscle weakness.     

Fibre type characteristics of the lumbar paraspinal muscles in normal healthy subjects and in patients with low back pain

A knowledge of the alteration in the fibre type profile of paraspinal muscle associated with low back pain is essential for the design of successful rehabilitation programmes. In attempting to compare the muscles of patients with low back pain with those of controls, few previous studies have considered factors such as gender, age, and size of the subjects, each of which can potentially confound interpretation of the results. We obtained samples of lumbar paraspinal muscle during spinal surgery from 21 patients with low back pain and, using the percutaneous biopsy technique, from 21 control volunteers matched for gender, age, and body mass. The samples were subject to routine histochemicsl typcal analysis to determine characteristics of muscle fibre type. Compared with controls, the muscle of the patients had a significantly higher proportion of type-IIB (fast-twitch glycolytic) fibres than type- I (slow oxidatve) fibres. The mean size of a given fibre type did not differ between the patients and the controls. Consequently, the relative area of the muscle iccupied by type-IIB fibres was higher and that by type-I fibres Was lower in the patients. The patients had a greater number of muscle samples with more than 1% type-IIC fibres, and abnormalities that could be described as pathological were more marked in the patients than in the controls. In conclusion, the paraspinal muscles of patients who have low back pain display a more glycolytic (faster) profile; this can be expected to render them less resistant to fatigue.     

Breast Cancer Genes

Abstract: The identification of familial breast cancer genes heralds an era of directed breast cancer treatment. Currently, two hereditary breast cancer genes have been identified, BRCA-1 and BRCA-2 . Although accounting for only approximately 5% of all breast cancers, they are being used to identify women with germ-line alterations that are at high risk of developing breast or ovarian cancer. With the identification of such genes comes a need for consideration of the ethical issues associated with testing. These genes are also being examined from a biochemical standpoint encompassing both their biological roles and biochemical pathways in which they reside. Such studies are likely to lead to novel breast cancer therapies.     

The effects of menstrual phase and nicotine abstinence on nicotine intake and on biochemical and subjective measures in women smokers: a A preliminary report

Nicotine intake, menstrual and smoking withdrawal symptomatology, and baseline cortisol and MHPG were assessed in nine women smokers under conditions of ad lib smoking and overnight abstinence in three menstrual phases (early follicular, mid-to-late follicular, and late luteal). A trend towards higher nicotine intake p <0.100 was observed in the mid-to-late follicular phase. Although me menstrual symptomatology was not significantly elevated during the smoking abstinence condition overall, abstinence appeared to prevent the normal reduction in symptomatology during the mid-to-late follicular phase that occurred under conditions of ad lib smoking. Menstrual and withdrawal symptoms were highly correlated, and both were most pronounced during the late luteal/abstinence condition. The smoking-specific item “craving” reflected this pattern, though in attenuated form, suggesting that the observed exacerbation of withdrawal symptomatology was not simply due to generalized dysphoria, as queried in both instruments. MHPG was significantly elevated in the late luteal phase, whereas cortisol was significantly higher during ad lib smoking than during abstinence and tended to be highest in the mid-to-late follicular phase. Further investigation will be needed to determine the functional significance of these findings for understanding and treating smoking in women.