Positive contrast ventriculography in cats with experimental obstructive hydrocephalus.

Cerebrospinal fluid pathways were studied in both normal and experimental obstructed hydrocephalic cats by positive contrast ventriculography. Either water soluble or insoluble contrast material was injected into the lateral cerebral ventricles, and radiographs were taken of the head and spinal cord. In the normal cat, the contrast material freely flowed throughout the spinal fluid spaces. The contrast material accumulated in the cisterna magna, and from there extended into the cranial and spinal subarachnoid spaces. In the kaolin-induced hydrocephalic cat, the outlets from the fourth ventricle were obstructed, and direct communication between the ventricular system and the subarachnoid spaces no longer existed. In these cats, the contrast material passed directly down the central canal of spinal cord and its movement was followed throughout the entire length of the canal. At the lower lumbar-sacral regions, the material perforated the cord and flowed into the subarachnoid space. At all levels, the central canal was enlarged and local dilatations were seen extending dorsally.     

Cable properties of spinal cord motoneurons in adult and aged cats

1. The electrophysiological properties of spinal cord alpha-motoneurons were investigated in adult cats (1-3 yr old) and old cats (14-15 yr old) using intracellular recording techniques. Voltage transients following depolarizing pulses of current were analyzed according to the procedure described by Ito and Oshima (15). The input resistance of each cell, together with the passive electrical time constants, were used to estimate the electrotonic length and total cell capacitance of each motoneuron. 2. Adult and old motoneurons both exhibited an undershoot of the membrane potential following the cessation of a subthreshold depolarizing current pulse (15). The average time constant for the decay of this undershoot in membrane potential was statistically indistinguishable in motoneurons of adult and aged animals. 3. The average membrane time constant of motoneurons in aged cats was 19% longer than that of motoneurons in adult cats. 4. The average total cell capacitance of motoneurons in aged cats was 16% smaller than that of motoneurons in adult cats. 5. The average electrotonic length of old motoneurons was statistically indistinguishable from that of motoneurons in adult cats. 6. From these results, we conclude that there is an age-dependent increase in the membrane resistance and an age-dependent decrease in cell surface area of alpha-motoneurons of the lumbar spinal cord in aged cats. Both of these phenomena are believed to contribute to the age-dependent increase in input resistance that has been previously reported to occur in motoneurons in aged cats (18).     

Risks of allergy vial contamination: Comparison of mixing in-office versus under ventilation hood

OBJECTIVE: Compare the risk of bacterial contamination of allergy immunotherapy vials prepared in-office versus those mixed under a ventilation hood. STUDY DESIGN: Prospective single-blinded study. SETTING: Tertiary otolaryngology outpatient clinic. RESULTS: Five hundred thirty-seven vials were prepared and cultured for aerobes and anaerobes over an 11-month period. Three hundred twenty vials were arbitrarily assigned to in-office preparation and 217 to under-hood preparation. A total of two positive cultures occurred in vials prepared in-office and one from under-hood preparation. Follow-up cultures of these three vials were all negative. No patients receiving injections had signs or symptoms of skin or systemic infections from the injections. CONCLUSION: Our results suggest that the risk of bacterial contamination in immunotherapy vials in both groups is rare.     

Comparison of the clinical pharmacology of (-)NPA and levodopa in Parkinson''s disease.

Direct acting dopamine agonists are generally less effective than levodopa in relieving symptoms of Parkinson's disease. In an attempt to quantitate and explain this situation, the acute motor responses to intravenous injections of the dopamine agonist, (-)-N-n-propyl-norapomorphine hydrochloride (NPA), were compared with those of the dopamine precursor, levodopa. At optimum dose levels, the acute anti-Parkinsonian efficacy of NPA averaged only about 50% of maximum, while essentially total symptom suppression was obtained with levodopa in patients previously treated with the amine precursor. Dyskinesia severity, however, was similar with the two drugs. These differences in anti-Parkinsonian efficacy may reflect the fact that while NPA acts mainly on D-2 dopamine receptors, levodopa results in stimulation of both the D-1 and D-2 subsets of receptors at a more physiological ratio. Future efforts to develop dopamine agonists for the treatment of Parkinsonian symptoms may thus have to consider focusing on drugs having pharmacological profile more similar to that of dopamine.     

Randomized crossover comparison of high-dose intravenous metoclopramide versus a five-drug antiemetic regimen

In a randomized open crossover study, the antiemetic efficacy of a five-drug antiemetic regimen consisting of metoclopramide, dexamethasone, diazepam, diphenhydramine, and thiethylperazine was compared to that of high-dose metoclopramide. Thirteen patients treated with cisplatin combination chemotherapy regimens were evaluated. The study was terminated prior to accrual of the planned number of patients because of the statistically significant difference in efficacy between treatments found at interim analysis. The duration of nausea and number of vomiting episodes on the day of chemotherapy were significantly less (p less than 0.01) after receiving the five-drug combination. After receiving the five-drug regimen, 77% of the patients did not experience any episodes of vomiting on day 1, and 8% of patients had only one episode. In contrast, only 31% of patients treated with high-dose metoclopramide did not have any episodes of vomiting on day 1, and 61% of the patients had five or more episodes. None of the patients treated with the five-drug regimen required additional antiemetic administration. Although both regimens were, in general, well tolerated, when given the choice of continuing antiemetic therapies, 92% of the patients preferred the five-drug antiemetic combination.