Variability in the stereotaxic position of cerebral points in the albino rat

An analysis of variability in the stereotaxic position of five cerebral points in rats revealed:

1. (1) that variability was less from the bregma skull point than from ear-bar-zero or the lambda skull point,

2. (2) that high correlations exist between the position of skull points and cerebral structures, and

3. (3) that the use of two external landmarks for predicting the position of cerebral targets produces a greater than 40% reduction in errors over that resulting from the use of single (ear-bar-zero or skull landmark) predictors.

Mechanical properties of normal andmdx mouse sarcolemma: Bearing on function of dystrophin

Summary The tensile strength of the muscle fibre surface membrane was estimated (1) from the suction required to burst membrane patches and (2) by aspiration of sarcolemmal vesicles into micropipettes of uniform bore. Each method gave an average value close to 60 N cm^–1 for the maximum tension sustainable by normal mouse sarcolemma and only slightly lower values for sarcolemma frommdx mice which lack dystrophin. The elastic modulus of area expansion, as measurable by pipette aspiration of sarcolemmal vesicles, was found to have an average value of 3160 N cm^–1 for normal and 2770 N cm^–1 formdx mouse sarcolemma.The tensile strength of the sarcolemma is much too small for any differences in it to be the basis for the different osmotic behaviour of normal andmdx muscle fibres reported recently (Menke & Jockusch, 1991). By analogy with the better understood origin of the osmotic fragility of different types of red blood cells, the higher osmotic fragility ofmdx muscle fibres is suggested to be of morphological origin. We postulate that dystrophin functions as an element of the submembrane cytoskeleton so as to maintain the normal folding which safeguards the sarcolemma against mechanical damage.     

Compartment syndrome of the interosseous muscles: early recognition and treatment.

A compartment syndrome of the interosseous muscles can be a challenging diagnosis as there is generally no neurovascular compromise to the digits involved. The most sensitive clinical sign is pain with passive motion at the metacarpal phalangeal joint of the involved digit. In this report, a 31-year-old man developed a compartment syndrome of the first, second, and third dorsal interosseous muscles following an injection of heroin in the "snuffbox" area. Compartmental tissue pressure measurements were 80, 75, and 55 mmHg respectively, and were a significant aid in the early diagnosis as well as management.     

Soft tissue sarcomas of adults: state of the translational science.

Sarcomas--like leukemias, which are also mesodermal malignancies--carry biological significance disproportionate to their clinical frequency. Identification of mutations and translocations associated with these tumors has illuminated aberrant signaling pathways that cause these diseases, determine their behavior, and are therapeutic targets. Activated receptor-associated tyrosine kinase c-kit, mutated in most gastrointestinal stromal tumors, has proven a clinically effective target for enzyme inhibition. A translocation involving a single gene family, consisting of EWS and related genes, has been identified in five different sarcomas, and its chimeric protein products could prove similarly amenable to inhibitors. Resolution of the histopathological complexity is being aided by data from molecular and chromosomal characterization. Improvements in imaging, definition of prognostic factors, and surgical and radiotherapeutic treatment have resulted in improved local control. Continued progress will depend on further adapting the rapidly evolving technologies of genomics and proteomics. It will also depend upon accurate histopathological diagnosis based on validated reagents and consistent methodologies applied to adequate tissue samples derived from patients with complete clinical data. Finally, multicenter, coordinated trials, such as those that occurred with assessment of imatinib mesylate in metastatic gastrointestinal stromal tumors, will assure the most rapid reductions in morbidity and mortality.     

Glutamatergic drugs exacerbate symptomatic behavior in a transgenic model of comorbid Tourette's syndrome and obsessive-compulsive disorder

We previously created a transgenic mouse model of comorbid Tourette's syndrome and obsessive-compulsive disorder (TS+OCD), by expressing a neuropotentiating cholera toxin (CT) transgene in a subset of dopamine D1 receptor-expressing (D1+) neurons thought to induce cortical and amygdalar glutamate output. To test glutamate's role in the TS+OCD-like disorder of these transgenic mice (D1CT-7 line), the effects of glutamate receptor-binding drugs on their behavior were examined. MK-801, a non-competitive NMDA receptor antagonist that indirectly stimulates cortical-limbic glutamate output, aggravated a transgene-dependent abnormal behavior (repetitive climbing and leaping) in the D1CT-7 mice at doses insufficient to induce stereotypies, and more readily induced stereotypies and limbic seizure behaviors at high doses. NBQX, a seizure-inhibiting AMPA receptor antagonist, reduced only the MK-801-dependent stereotypic and limbic seizure behavior of D1CT-7 mice, but not their transgene-dependent behaviors. These data imply that TS+OCD-like behavior is mediated by cortical-limbic glutamate, but that AMPA glutamate receptors are not an essential part of this behavioral circuit. Our findings lead to the prediction that the symptoms of human Tourette's syndrome and obsessive-compulsive disorder are elicited by excessive forebrain glutamate output.