In-vitro antagonism by N-formimidoyl thienamycin and cefoxitin of second and third generation cephalosporins in Aeromonas hydrophila and Serratia marcescens

Antagonism of beta-lactam antibiotics by second and third generation cephalosporins was studied in 28 clinical strains of Serratia marcescens and Aeromonas hydrophila. Of the antibiotics tested, both cefoxitin and N-formimidoyl thienamycin (N-f-thienamycin) were capable of antagonism in Ser. marcescens (17 of 20) but in Aerom. hydrophila (7 of 8), only cefoxitin induced antagonism. Antagonism was observed to the greatest degree with cefotaxime and cefoperazone; intermediate with cefamandole and latamoxef (moxalactam) and essentially none with N-f-thienamycin. Inducible beta-lactamase was found in all strains of both genera which exhibited antagonism. The induced beta-lactamase showed enhanced inactivation for other antibiotics in only four strains with none occurring in Aeromonas.

Early peripheral responses to intravenous L-thyroxine in primary hypothyroidism

The metabolic, cardiovascular, renal, and pulmonary responses of 10 hypothyroid patients were studied during the first week of therapy with intravenous levothyroxine (L-thyroxine), 100 micrograms per day. Mean serum thyroxine, triiodothyronine, and reverse triiodothyronine concentrations were normalized within four days. Significant decreases in serum thyrotropin, creatine phosphokinase, and cholesterol levels, and an increase in the basal metabolic rate, were observed. An early cardiovascular response was demonstrated by serial measurement of the mean pre-ejection period (138 to 134 msec, p less than 0.05), its ratio to left ventricular ejection time (0.49 to 0.46, p less than 0.02), and pulse-wave arrival time (236 to 224 msec, p less than 0.05). The mean renal excretion of a water load (four hours) increased (54 to 77 percent, p less than 0.02) by the fourth day. The blunted ventilatory responses to hypercapnea seen in two patients were improved. We conclude that a physiologic replacement dose of intravenous L-thyroxine for one week produces significant responses in organ systems responsible for the common clinical complications of myxedema.

Inhibition of Neisseria gonorrhoeae isolates by Martin-Lewis medium. Epidemiology, susceptibility profile, and plasma analysis

A study was undertaken on the premise that if an increase of 1 microgram/ml in the concentration of vancomycin in Martin-Lewis medium (MLM) could improve inhibition of Gram-positive cocci, then a concomitant increase in the inhibition of gonococci could also occur. Isolates of Neisseria gonorrhoeae that failed to grow on MLM accounted for 18-5% of all positive culture results for gonorrhoea. The incidence of isolates susceptible to vancomycin was 14% and of those susceptible to trimethoprim 2.4%; one isolate was susceptible to both vancomycin and trimethoprim. The antibiotic-susceptible isolates were more frequently isolated from asymptomatic white men. Plasmid analysis showed that the 2.4-megadalton cryptic plasmic was absent in the vancomycin-susceptible isolates. The large proportion of isolates failing to grow on selective MLM has important clinical implications for the diagnosis of gonorrhea.

Defibrination with ancrod in glomerulonephritis: effects on clinical and histologic findings and on blood coagulation

Ancrod, which produces in vivo defibrination, has been shown to improve renal function and decrease fibrin deposition and crescents in experimental glomerulonephritis. Ancrod was given for 14 days to 5 patients with glomerulonephritis, moderate to severe renal functional impairment, crescents, and/or fibrin deposition in glomeruli. 4 patients had systemic lupus erythematosus. Ancrod treatment resulted in fibrinogen levels less than 50 mg/dl without bleeding, decrease of previously elevated factor VIII and von Willebrand factor levels, and normalization of in vitro platelet hyperaggregation. Renal function improved in all 5 patients. Serial renal biopsies showed a relatively rapid decrease of glomerular thrombi and necrosis and little increase in glomerular sclerosis. Ancrod administration appears safe, and may have a role in treatment of certain types of glomerulonephritis.

The lupus inhibitor: a study of its heterogeneity

The plasmas of six patients with prolonged activated partial thromboplastin times were studied in detail. In five of the six, the Russell's viper venom and prothrombin times were likewise prolonged. Five of the patients had documented systemic lupus erythematosus; one lacked the necessary criteria for this diagnosis. On quantitation, factor XI was decreased in all six; factors X and XII were diminished in five of the six. When tested for inhibitory activity, plasma from each of the patients prolonged the celite eluate inhibition test for factor XII and/or XI inhibition. In the formation of the Xa-V-phospholipid-Ca2+ complex (prothrombinase), factors X and Xa were inhibited to a greater degree than factor V or the phospholipid. Finally, each plasma was isofocused, the inhibitory fractions were identified and the clotting factor specificity of each inhibitory peak was determined. Fractions inhibitory against factors XI and XII isofocused with the IgG in each patient's plasma. Based on the data presented from these six patients, the "lupus inhibitor" is in fact a heterogeneous collection of inhibitors directed against factors XII, XI and X rather than a homogeneous entity.

Comparative activity of N-formimidoyl thienamycin with third generation cephalosporins and ureido penicillins against multiple resistant Serratia marcescens

Twenty multiple resistant clinical isolates were tested with N-formimidoyl thienamycin, moxalactam, cefotaxime, cefoperazone, and the three ureidopenicillins: azlocillin, mezlocillin, and piperacillin. A concentration of less than 0.97 microgram/ml inhibited 100% of organisms for N-f-thienamycin and cefotaxime, 90% for moxalactam, and 60% for cefoperazone. An increase in inoculum from 10(3) to 10(6) cells reduced activity fourfold for 95% of isolates with cefoperazone, 70% with N-formimidoyl thienamycin, 65% for cefotaxime, but only 15% for moxalactam. For ureidopenicillins, 85% of strains tested had MIC's less than or equal to 15.6 micrograms/ml. An inoculum effect was observed in only 35-50%. At 10(3), the cidal concentration was the same or twofold greater than the inhibitory level for N-f-thienamycin and cephalosporins in 70% of strains tested and 65% for penicillins. With 10(6), the 70% value remained for N-f-thienamycin but was reduced to 45% for cefotaxime and 25% for moxalactam; 85% demonstrated greater than eightfold differences with cefoperazone. Single step high-level resistance was observed to moxalactam (20%). Carbenicillin resistant strains were cross-resistant to the ureidopenicillins. N-f-thienamycin and cefotaxime appeared comparable, although important differences between morphological alteration and metabolism may influence their therapeutic effectiveness.

Stability of alveolar hypoxic vasoconstriction with intermittent hypoxia

Repeated intermittent global hypoxia has been reported to markedly enhance hypoxic pulmonary vasoconstriction in dogs. We have reexamined this phenomenon but with intermittent unilateral alveolar hypoxia, avoiding complications of systemic hypoxemia. Fifteen anesthetized dogs were intubated with a double-lumen endotracheal tube, allowing separate ventilation of one lung with 100% N2 as a hypoxic challenge and the other lung with 100% O2 to maintain adequate systemic oxygenation. Distribution of lung perfusion was determined with intravenous 133Xe and external chest detectors. Each dog alternately breathed air or the unilateral alveolar hypoxia combination for 15 min each for a total of 12 hypoxic challenges or 6 h. Two groups emerged on the basis of the strength of their vasoconstrictor responses to successive hypoxic challenge. In group I (n = 6), perfusion to the hypoxic lung decreased 29% with the first challenge and decreased comparably with successive challenges. In group II, vasoconstriction was initially weak with perfusion decreasing only 5%, but perfusion decreased further with time alone (n = 5) or successive challenges (n = 4), falling 35% on the 12th challenge (comparable to group I). Delayed achievement of hypoxic vasoconstriction in group II may be secondary to a vasodilating prostanoid that disappears with time.

Significance of scintillating scotoma of late onset

Scintillating hemianopic scotomas are usually caused either by migraine or, more rarely, vertebral-basilar insufficiency. We report two patients in whom this symptom was probably caused by platelet microthrombi in pial vessels of the visual cortex. These patients were similar in that they had scintillating scotomas which began after the age of fifty and abnormal platelet aggregability. Since increased platelet aggregability is associated with cerebral vascular accidents and is treatable, older patients who develop teichopsias should have appropriate hematological tests.

Cytoplasmic membrane proteins of spectinomycin-susceptible and -resistant strains of Neisseria gonorrhoeae

Cytoplasmic membranes were isolated and examined from two spectinomycin-susceptible and three spectinomycin-resistant clinical strains of Neisseria gonorrhoeae. A laboratory-derived spectinomycin-resistant mutant, obtained by serial passage on gradually increasing concentrations of the antibiotic, and a susceptible revertant, spontaneously arising from one of the resistant clinical strains, were also studied. Sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis revealed that a major protein, comprising about 7% of total cytoplasmic membrane protein (molecular weight 24,000), was absent in the three clinically isolated spectinomycin-resistant strains. In a revertant, this protein reappeared. During treatment of one of the susceptible strains with spectinomycin, the protein disappeared. However, this correlation was not maintained in the laboratory-derived spectinomycin-resistant mutant. This mutant was of comparable resistant to the clinical isolates, but the 24,000-molecular-weight protein was present in normal quantities. In addition, spectinomycin resistant in clinical isolates was variable compared with stable resistance exhibited by the laboratory-derived mutant. These findings suggested that differences in laboratory-derived versus clinical spectinomycin resistance may be due to different types of resistance mutations.

In vitro activity of cefamandole, cefoxitin, cefuroxime, and carbenicillin, alone and in combination with aminoglycosides against Serratia marcescens

Synergistic antibiotic studies were undertaken to compare the effectiveness of two new beta-lactamase resistant cephalosporins, cefamandole, and carbenicillin, with four aminoglycosides against clinical strains of Serratia marcescens. The strains demonstrated various combinations of resistance and/or susceptibility to the antibiotics tested. Tobramycin was the most effective aminoglycoside when used in combination with beta-lactam antibiotics. Carbenicillin and cefamandole demonstrated similar activity with aminoglycosides in synergy experiments. Tobramycin-carbenicillin was found to be the superior pairs as indicated by the total number of strains inhibited. This combination was the only one effective against certain high drug resistant strains and the strain resistant to all four aminoglycosides. Carbenicillin or cefamandole with tobramycin exhibited comparable activity against multiple drug resistant organisms. However, mutants significantly more resistant to cefamandole developed during susceptibility testing. The findings of this study have clinical relevance for treating infections by this formidable pathogen.

Role of cytochrome P-450 in alveolar hypoxic pulmonary vasoconstriction in dogs

Alveolar hypoxia induces pulmonary vasoconstriction by an unknown mechanism. Cytochrome P-450 (C-P450) is found in the lung and may modify pulmonary vascular tone via its sensitivity to changes in oxygen tension or by affecting metabolism of a chemical mediator. Metyrapone and carbon monoxide are both inhibitors of C-P450. We tested alveolar hypoxic pulmonary vasoconstriction (AHPV) in 20 dogs before, during, and after separate administration of each inhibitor. Anesthetized dogs were ventilated through a double lumen endotracheal tube allowing ventilation of one lung with N(2) or CO as a hypoxic challenge and ventilation of the other lung with O(2) to maintain adequate systemic oxygenation. Distribution of lung perfusion was determined with intravenous (133)Xenon and external chest detectors. Before infusion of metyrapone, mean perfusion to the test lung decreased 30% with alveolar hypoxic challenge, but decreased only 10% during metyrapone infusion and returned to a base-line mean decrease of 31% after completion of metyrapone infusion. Prostaglandin F(2) alpha and angiotensin II infusions produced equivalent increases in pulmonary vascular resistance before and during metyrapone infusion. Before CO, mean test lung perfusion decreased 31% with alveolar hypoxia but was reduced only 10% from control when unilateral end-tidal CO% was >75%. Washout of alveolar CO with unilateral N(2) ventilation restored AHPV, with perfusion decreasing 29% from control. Thus, both metyrapone and carbon monoxide can reversibly inhibit AHPV. C-P450 may, therefore, be involved in the transduction process of the vasoconstrictor response to alveolar hypoxia.

Multiple peripheral pulmonary carcinoids and tumorlets of carcinoid type, with restrictive and obstructive lung disease

Multiple peripheral carcinoid tumors were found on lung biopsy in a 53 year old woman with an eight year history of pulmonary nodules. The biopsy specimen showed nodules varying from 1 to 7 mm in greatest diameter. The larger lesions were typical bronchial carcinoids whereas the smaller ones resembled pulmonary "tumorlets." Electron microscopy showed neurosecretory granules typical of carcinoids. The common multicentric origin of carcinoids and tumorlets from Kulchitsky cells is discussed. Pulmonary function testing revealed mild obstructive and restrictive defects, both attributed to the carcinoid tumors. The history, pathology and physiology of this unusual case are presented in detail, with a review of the literature. Obstructive airways disease, presumably due to the extensive bronchiolar involvement, has not previously been reported in this entity.

Factors which influence blood platelet migration

Migration of human blood platelets in vitro was investigated by a modification of the capillary-tube migration chamber technique used to study the migration inhibition factor of macrophages. Platelets were packed in capillary tubes and incubated in autologous platelet-free plasma (PFP). The extent of migration was quantified by planimetry (measurement of the area of platelet migration visible by stereomicroscopy). Among the various anticoagulants employed, sodium citrate was most suitable for studying platelet migration. Optimal migration occured at 22 degrees to 37 degrees C and pH 7.2 to 7.4. Migration was inhibited by metabolic inhibitors such as iodoacetic acid, sodium fluoride, and 2,4-dinitrophenol, and inhibition was proportional to the dose of the agent added to the incubation medium. Mobility was also inhibited by cytochalasin B, which disrupts cellular microfilaments, at 1 microgram/ml PFP, but not by colchicine, a microtubule inhibitor, even at 40 microgram/ml of PFP. Light and electron microscopy showed that this inhibition was not ascribable to platelet clumping. These observations suggest that platelet mobility is an active process. The possible significance of platelet migration in hemostasis is discussed.

Kininogen deficiency in Fitzgerald trait: role of high molecular weight kininogen in clotting and fibrinolysis

Plasma from an asymptomatic person with defects in blood coagulation, release of kinin, and evolution of fibrinolytic activity upon contact with a foreign surface was deficient in kininogen. The coagulation defect was identified as "Fitzgerald trait." A preparation of high molecular weight kininogen repaired the defects in clotting, kinin release and fibrinolysis, but a preparation of low molecular weight kininogen did not. Therefore, Fitzgerald factor appears to be a high molecular weight kininogen. The site of action of the kininogen appears to be after that of activated Hageman factor and kallikrein in the generation of clot-promoting activity through activation of plasma thromboplastin antecedent (PTA).

Relation of beta-lactamase activity to antimicrobial susceptibility in Serratia marcescens

One-hundred clinical isolates of Serratia marcescens were tested for susceptibility to cephalothin, carbenicillin, ticarcillin, ampicillin, and cefoxitin. The majority of the 100 isolates (>/=70%) were susceptible to carbenicillin, ticarcillin, and cefoxitin; less than one-half were susceptible to ampicillin; none were susceptible to cephalothin. Ten isolates from the 100 organisms tested were selectively assayed for their beta-lactamase activity. Enzyme activity was measured using either iodometric or spectrophotometric methods, and the microbiological assay technique. It was concluded that beta-lactamase production was not the sole determinant in beta-lactam antibiotic resistance. Resistance without demonstrable beta-lactamase was evident in strains for cephalothin, ampicillin, and cefoxitin. In addition, one strain which was susceptible to all antibiotics except cephalothin, elaborated considerable beta-lactamase activity.

California encephalitis virus prevalence throughout the Yukon Territory, 1971-1974

California encephalitis (CE) virus (snowshoe hare subtype) was isolated from 1 of 38 pools comprising 970 unengorged female Aedes canadensis mosquitoes and from 3 of 152 pools containing 5,676 A. communis mosquitoes which were collected in the Yukon Territory, Canada between latitudes 61 and 66 degrees N during June and July 1974. During four summers 1971 through 1974, this virus was recovered from 26 of 648 pools derived from 30,686 mosquitoes of 4 species. Isolation of CE virus from 1 of 109 pools of Aedes sp. larvae collected during May 1974 suggests maintenance of this virus over winter by transovarial transfer. Infectivity has been maintained in Culiseta inornata mosquitoes which were held continuously at 32 degrees F for 138 days. Neutralizing antibodies to CE virus were detected in 705 of 4,913 (14%) mammals collected during summers 1971 through 1974, including 430 of 1,076 (40%) snowshoe hares (Lepus americanus), 266 of 3,610 (7%) ground squirrels (Citellus undulatus) and 9 of 227 (4%) red squirrels (Tamiasciurus hudsonicus).