Collateral sensitivity to nitrosoureas in multidrug-resistant cells selected with verapamil.

We have examined the effects of the nitrosoureas, streptozotocin (STZ) and 1,3-bis(chloroethyl)-1-nitrosourea (BCNU), on a human multiple myeloma cell line, RPMI 8226, and its drug-resistant variants. Cell lines selected for doxorubicin (DOX) resistance alone displayed a STZ and BCNU cytotoxicity profile similar to that of the parent cell line. In contrast, two of the drug-resistant variants selected with DOX plus verapamil, an agent which inhibits P-glycoprotein-mediated multidrug resistance, displayed a collateral sensitivity to STZ and BCNU. Verapamil was included in the selection protocol because it has been shown to inhibit the P-glycoprotein-mediated multidrug resistance phenotype and is now in clinical trials as a chemosensitizing agent. The collateral sensitivity to these nitrosoureas seen in the DOX plus verapamil-selected cell lines is due to the functional loss of a DNA repair molecule, O6-Methylguanine DNA methyltransferase (MGMT). The functional loss of MGMT is secondary to the loss of MGMT gene expression. The loss of MGMT gene expression is not due to loss or gross rearrangement of the MGMT-coding region. If this selection pressure applied in vitro reflects the in vivo situation, then new chemotherapeutic strategies may be devised to exploit this phenomenon. These cell lines will serve as useful models for delineating mechanisms which govern MGMT expression.     

Exacerbation of lymphocytic choriomeningitis in mice treated with the inducible nitric oxide synthase inhibitor aminoguanidine

To elucidate the possible involvement of the inducible nitric oxide synthase (iNOS) and NO in the development of lymphocytic choriomeningitis (LCM), the consequences of inhibition of iNOS by the inhibitor aminoguanidine was examined in mice following intracerebral infection with LCM virus (LCMV). Aminoguanidine administration to mice infected with LCMV completely blocked increased plasma nitrate/nitrite levels and led to increased proinflammatory cytokine gene expression at early stages of lesion development in the brain, enhanced clinical severity and decreased survival time. The levels of LCMV recovered from the brain of aminoguanidine treated mice did not differ from those in infected control mice. These findings argue against either an anti-viral or pathogenic role of NO in LCM but rather suggest a possible protective action of this mediator.     

Efficacy of the dorsal pedal bypass for limb salvage in diabetic patients: short-term observations

Limbs of diabetic patients with distal tibial disease are frequently considered unreconstructible; however, when studied with intraarterial digital subtraction angiography, the dorsal pedal artery is frequently found to be patent. We have reviewed our recent experience with 96 patients, 94% of whom had diabetes and had 97 bypasses placed to the dorsal pedal artery. All procedures were for limb salvage. Superimposed infection was present in 42.3%. In 92 instances where intraarterial digital subtraction angiography successfully visualized the dorsal pedal artery, 91 bypasses were placed. In 12 other cases where the dorsal pedal artery was not visualized by intraarterial digital subtraction angiography but audible with the continuous-wave Doppler, bypasses were completed successfully in six. All procedures were performed with vein. Inflow was taken from the femoral artery in 48, popliteal artery in 45, tibial artery in 2, and from a femoral tibial graft in 2. Perioperative mortality was 1.92%. Actuarial graft patency, limb salvage, and patient survival were 82%, 87%, and 80%, respectively at 18 months. We conclude that bypass grafting to the dorsal pedal artery can be reliably performed with acceptable short-term results. An attempt should always be made to visualize the foot vessels angiographically, especially in diabetic patients, so that this valuable option in arterial reconstruction will not be overlooked.     

Phaeohyphomycosis caused by Bipolaris spicifera: An informative case

A case of phaeohyphomycosis caused by Bipolaris spicifera involving the brain and sinuses is presented. The patient survived following surgery and ketoconazole therapy, which successfully treated both the sinus and the brain infections.     

Bilateral aberrant internal carotid arteries.

This case report represents the first well-documented case of aberrant internal carotid arteries in both middle ears. CT and DSA can establish the diagnosis before surgical intervention. Aberrant internal carotid artery represents a rare finding in the differential diagnosis of middle ear masses. Most patients manifest either vertigo, tinnitus, or a variable hearing loss. Clinical findings include a red or blue mass behind the eardrum that may or may not be pulsatile. The otolaryngologist should be aware that this potential landmine may be obscured by serous otitis media. Once suspected, the mass should be evaluated by radiographic studies before surgical intervention.     

Cytochemical characteristics of neurons in the trigeminal mesencephalic nucleus of hatchling chicks

The goal of the present study was to identify cytochemical markers characteristic of muscle afferents in hatchling chicks. To this end, we stained neurons in the trigeminal mesencephalic nucleus with a variety of markers that label subsets of neurons in avian dorsal root ganglia. We found that trigeminal mesencephalic neurons are surprisingly heterogeneous in their cytochemical make-up, expressing, to varying degrees, substance P, cholecystokinin, carbonic anhydrase, calbindin D-28k, parvalbumin, and S-100β. Calbindin D28k and S-100β appeared to be expressed equally in medial and lateral divisions of the trigeminal mesencephalic nucleus. In contrast, substance P- and cholecystokinin-immunoreactive neurons were more abundant in the medial division, whereas carbonic anhydrase activity and parvalbumin immunoreactivity were stronger in the lateral division. We were unable to detect met-enkephalin, neuropeptide Y, calcitonin gene-related peptide, vasoactive intestinal peptide, somatostatin, γ-aminobutyric acid, or tyrosine hydroxylase in the trigeminal mesencephalic nucleus. Moreover, these neurons did not appear to bind the lectin Dolichos biflorus agglutinin. The heterogeneity of expression of markers among trigeminal mesencephalic nucleus neurons, especially between neurons in the medial and lateral divisions, suggests that these neurons are functionally diverse.     

Ankylosing spondylitis antirheumatic drug trials. III. Setting the delta for clinical trials of antirheumatic drugs--results of a consensus development (Delphi) exercise.

Defining the minimum clinically important difference or delta to be detected in a clinical trial depends on a number of factors including the research hypothesis, patient characteristics, the nature of the intervention and the trial design. In 2 previous studies, we have developed standardized procedures for conducting outcome measurement based on current Food and Drug Administration and European League Against Rheumatism guidelines for clinical trials in ankylosing spondylitis, and thereafter, determined the standard deviation for these outcome measures. In the final component of this series of studies, we have employed a Delphi technique to establish estimates for delta, and calculated the sample size requirements under 2 different conditions of Type I and Type II error probabilities.     

Interleukin-2 and granulocyte-macrophage colony-stimulating factor stimulate growth of a virulent strain of Escherichia coli.

The effect of human recombinant interleukin-2 (IL-2) and human recombinant granulocyte-macrophage colony-stimulating factor on the growth of a virulent strain of Escherichia coli in tissue culture medium and in untreated, normal mouse serum was investigated. Both of these cytokines enhanced the growth of the microorganism two- to threefold in tissue culture medium with or without additional fetal calf serum and in untreated mouse serum. IL-4 did not have any effect on the growth of this microbe under the conditions tested. That the enhancement of growth seen with recombinant IL-2 was due to the active cytokine was shown by the following data: (i) addition of an antibody to IL-2 abrogated the growth-promoting effect; (ii) the excipient buffer, which contained everything except the active cytokine, was inactive in modifying bacterial growth; and (iii) heat-inactivated recombinant IL-2 did not promote enhanced microbial growth. The enhancement of growth with IL-2 was significant with concentrations as low as 1 U/ml. Growth of an avirulent strain of E. coli was not stimulated by IL-2. Moreover, addition of IL-2 to growth virulent E. coli in tissue culture medium led to rapid removal of the cytokine from the medium. Collectively, these data suggest that cytokines may act as growth factors for some virulent bacteria.