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Biomedical subjects

D M Cohen

Publications and source records attributed to D M Cohen.

At least 145 records · Page 8Linked to original sources
PubMed1975

Inhibitory effects of citrates in the determination of trace amounts of penicillin.

In the microbiological assay for the determination of trace amounts of penicillin, it has been shown that sodium citrate and penicillin act synergistically against Sarcina lutea. The inhibitory action of citrate appears to involve a sequestering of divalent cations essential to the growth of the organism as shown by minimal inhibitory concentration and agar diffusion studies. The addition of calcium or magnesium to broth or agar at various concentrations overcomes this inhibition, and 0.02 M magnesium was found to be the most effective concentration. On agar supplemented with magnesium chloride, penicillin dose-response curves with and without citrate present were practically superimposable, and larger inhibition zones against a greater amount to total growth resulted in improved assay susceptibility and an interference-free method. Misleading results can be obtained when pharmaceutical products containing citrates are tested by conventional methods for penicillin cross-contamination.

Biological Assay↗
PubMedDate not supplied

Evidence of hypertriglyceridemia in managing HIV patients on efavirenz.

Of the recently approved antiretroviral agents, efavirenz has become a popular medication for the treatment of HIV infection. The efficacy of an efavirenz-based regimen has allowed the use of a combination of this medication with other antiretroviral agents in all levels of HIV disease, resulting in decreased viral replication and positive clinical results. Efavirenz is also proposed as an acceptable agent to switch to from a protease inhibitor-based regimen to reduce the risk of metabolic complications. In addition, the favorable side-effect profile, diminished pill burden for clients, and daily dosing have contributed to its popularity. Primary care practitioners should be cognizant of the possible side-effect profile of antiretroviral therapy combinations and enter into a collaborative relationship with the infectious disease clinician to ensure safe and effective patient care.

Alkynes↗
PubMedDate not supplied

Quantitative digital angiography as an adjunct to the intraoperative placement of endovascular stents in congenital heart disease.

Clearly identifiable intraoperative landmarks render the placement of intraoperative stents difficult. Preoperative use of quantitative digital angiography helps the surgeon accurately insert endovascular stents intraoperatively. By using defined points of reference, we were able to carefully select the size and lengths of stents before the operation and precisely place these stents in the operating room. Furthermore, we have been able to redilate these stents using the same techniques at subsequent operations. Our results reflect the efficacy of this technique.

Angiography, Digital Subtraction↗
PubMedDate not supplied

Nitroprusside-induced vascular relaxation in DOCA hypertensive rats.

Vascular responsiveness to nitroprusside and to norepinephrine was examined in two different preparations from DOCA hypertensive and normotensive control Sprague-Dawley rats. The blood-perfused renal vasculatures of DOCA hypertensive rats were significantly more sensitive than those of normotensive controls to the vasodilator action of low doses of nitroprusside. At high doses, responses in DOCA hypertensive and normotensive rats were similar. Since basal "structural" vascular resistances were greater in the hypertensive rats, It is possible that further vasodilation with nitroprusside was impeded more in DOCA-treated than in control rats. Nitroprusside produced a greater degree of vascular smooth muscle relaxation in tail artery strips from DOCA hypertensive rats than in those from normotensive controls. The current study is the first characterization of the effects of a vasodilator in mineralocorticoid hypertension. The two preparations gave divergent results with respect to vascular sensitivity to norepinephrine. When compared with control rats, the DOCA hypertensive rats showed a greater sensitivity to norepinephrine in tail arteries but a lesser renal vascular reactivity. It is evident that one must take a number of variables into consideration when characterizing changes in vascular responses that occur in a given model of hypertension: 1) the region of the vasculature (renal vs caudal artery);2) the level of the arterial tree (conduit vs resistance vessels);3) the technique employed for measurement of vascular changes (smooth muscle contraction vs vascular resistance changes);4) the initial vasoconstrictor tone of the preparation; and 5) the agonist used (nitroprusside vs norepinephrine).

Animals↗
PubMedDate not supplied

Recurrent ingrown toenails secondary to indinavir/ritonavir combination therapy.

OBJECTIVE: To report five cases of ingrown toenails (IGTN) associated with indinavir/ritonavir (IDV/RTV) combination therapy. CASE SUMMARY: The median onset of IGTN from initiation of IDV/RTV therapy was 18.4 weeks. Four patients previously received IDV, with one of these experiencing prior IGTN. All patients required surgical management of IGTN. All patients received virologic benefit from ongoing antiretroviral therapy, and the majority of patients elected to maintain IDV/RTV combination therapy. Two patients experienced recurrent IGTN while receiving ongoing IDV/RTV combination therapy. DISCUSSION: IGTN and paronychia have previously been reported with IDV and lamivudine. IGTN in patients with HIV infection is more likely to present acutely, involve more digits, and require surgical management IDV increases retinoic acid signaling and, based on elevated IDV concentrations from concomitant RTV therapy, the risk of IGTN may be increased in patients receiving IDV/RTV combination therapy. CONCLUSIONS: With the increasing popularity of IDV/RTV combination therapy, clinicians should be aware of the potential increase in frequency of dose-related toxicities including IGTN. Evaluation of hands and feet on physical examination should be recommended for all patients being treated with lamivudine and IDV, especially when used in combination with RTV.

Adult↗