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Neisseria gonorrhoeaewas cultivated in mammalian cell cultures in an effort to determine if this environment will elicit a T4 → T1 transition. Of four avirulent (T4) isolates tested, only one, H4, yielded T1 colonies. This change was consistently obtained in HeLa, WI-38, and MK2 cells, even when the multiplicity of the gonococcal infection was less than 1 per culture. Growth of the gonococci took place primarily on the surface of the cells, as demonstrated by light and electron microscopy, but occasional bacteria were undoubtedly intracellular. T1 colonies were seen at 24 h and were the major population at 48 h. This shift was favored by the presence of viable cells, since smaller yields of T1 were obtained when the cells were irradiated or heat inactivated. It was also favored by low pH, since T1 recovery was reduced when the buffering capacity of the medium was increased. Although the results suggest that T1 gonococci derived from H4 have a selective advantage over T4 in cell cultures, this is not true of all T1 and T4 colony types. F62 T4, which does not undergo a T4 → T1 shift, propagated as well as T1 in HeLa cell cultures. The change in colony type of strain H4 to T1 was accompanied by formation of pili and by gain in capacity for deoxyribonucleic acid-mediated transformation. It is concluded that gonococci can undergo T4 → T1 phase transition in mammalian cell cultures, but this property is not retained by all strains.

The authors emphasize the need for radical surgery in the excision of the cancer of the colon or rectum which has invaded neighboring structures. This is advocated as long as there is no evidence of distant metastases elsewhere and provided the patient is a substantially good surgical risk, capable of withstanding the added procedures and anesthesia.

Saline and antibiotic solutions, with and without ascorbic acid, were injected into 7-day-old chick embryos inoculated with Leptospira icterobaemorrbagiae1day after infection. All inoculations were made into the yolk sac. The treated embryos were observed for prolongation of life and for survival rates over a period of 12 to 14days. Demethylchlortetracycline was about twice as active as tetracycline and oxytetracycline and about 10 times as active as chlortetracycline. Ascorbic acid alone did not influence the course of the infection and did not affect their therapeutic activity when given with antibiotics.

TAYLOR et al.1 recently described a new, unusually potent, non-hydrazine, monoamine oxidase inhibitor: pargyline hydrochloride (MO-911). Horwitz and Sjoerdsma,2 in 9 hospitalized hypertensive subjects, observed marked orthostatic hypotension and a minimum of side-effects with this compound and suggested that extensive clinical trials were warranted. The latter investigators also pointed out that none of the numerous monoamine oxidase inhibitors previously studied had become valuable therapeutic agents for hypertension, either because of low potency or prohibitive toxicity.The purpose of the present study is to evaluate the hypotensive changes of pargyline hydrochloride in ambulatory hypertensive outpatients in relation to long-term control of blood pressure values and to compare them with those observed with sulphonamide diuretics. PHARMACOLOGY Pargyline hydrochloride is a member of a different chemical series from the hydrazide type of monoamine oxidase inhibitors in current clinical use. Chemically, it is N-benzyl-N-methyl-2-propynylamine hydrochloride and is readily soluble but unstable in

Currently, neurogenic blockade is used as a supplement to sulfonamide-diuretics (with or without reserpine) when optimal antihypertensive control is not obtained with these drugs alone. Although the use of neurogenic blocking agents preceded that of sulfonamide-diuretics by ten years, the latter have become first in therapeutic choice.A combination of chlorthalidone and reserpine produced normotension in 58 of 100 ambulatory outpatients with moderate to severe essential hypertension. Twentytwo of 42 subjects with residual hypertension became normotensive when chlorthalidone-reserpine therapy was augmented with a postganglionic sympathetic blocking agent (debrisoquin sulfate).In the authors' opinion neurogenic blocking agents, or other potent antihypertensive drugs as adjuncts to sulfonamide-diuretics, are indicated in approximately 40% of patients with moderate or severe essential hypertension. Debrisoquin appears to be more practical, as a supplementary antihypertensive drug, than older related blocking agents.

The Orenda OT-4 is a gas turbine which uses a simple regenerative cycle and is being developed as a multipurpose, continuous or emergency unit which will be competitive with the diesel engine and will retain the inherent advantages of the gas turbine. This development program is now in its fourth year. The design and development philosophies used in this engine are discussed briefly. The problems still facing the engine are indicated. Some of the experience and lessons learned from this program are discussed.

The diagnosis of trachoma can be easily established in the typical case, by using the specific clinical criteria well summarized recently by Thygeson1 and by finding Halberstaedter-Prowazek inclusion bodies in a smear of epithelial scrapings. There are many clinically doubtful cases, however, in which the diagnosis is difficult to make. This is particularly true when the question of a recurrence arises in a case of healed trachoma with residual scarring. It has also been found that in surveys made to reveal the true incidence of trachoma in a population, or to study its treatment, the presence of nontrachomatous chronic follicular conjunctivitis can confuse the picture, particularly in the diagnosis of very early trachoma.2 It is clear that improved methods are needed for detecting trachoma infection. A good laboratory method would be especially useful in those trachomatous populations that do not have the services of trained ophthalmologists.Other than

1Rabbits were fed sucrose- or lactose-containing diets and cholesterol varying from trace amounts to 0.5% of the diet for 8 to 13 weeks. The maximal difference in cholesterol metabolism and atherosclerosis between the groups fed sucrose or lactose was observed when 0.35% of cholesterol was added to the diet. Essentially no difference in serum and liver cholesterol values and atherosclerosis was obtained when 0.5% of cholesterol was added to the sucrose- and lactose-containing diets.2The addition of 0.5 or 1% of succinylsulfathiazole (SST) to a 0.35% cholesterol-sucrose-containing diet fed to male rabbits for 8 weeks resulted in serum and hepatic cholesterol levels and atherogenesis comparable to that of the lactose-supplemented 0.35% cholesterol-containing diet. The supplementation of both SST and lactose in the diet produced essentially the same response in the rabbit as that obtained with either component alone added to the diet.3During an 8-week experimental period, the restriction of the feeding pattern of rabbits given a 0.35% cholesterol-sucrose-containing diet for two or three onehour intervals daily resulted in higher serum and liver cholesterol values and degree of atherosclerosis than the corresponding values of the ad libitum-fed controls. This effect was not observed if the diet contained 29.35% of lactose in place of sucrose. Sucrose- or lactose-containing diets consisting of either a trace or 0.7% of cholesterol were fed to rabbits on a daily alternation schedule for 8 weeks. Serum and liver cholesterol content and atherogenesis was comparable to that observed in rabbits fed the corresponding carbohydrate diets containing 0.35% of cholesterol continuously. The serum cholesterol values of the sucrose-alternate-fed groups, however, were higher than the corresponding values for the sucrose-0.35% cholesterol-fed rabbits.

1.Rats were fed a meal of cholesterol-4-C14and the cholesterol recovered in thoracic duct lymph during the first 24 hours was studied. The sucros-fed animals absorbed an average of 7.5% of the isotope whereas rats fed a 40% lactose-containing diet absorbed 19.6% of the cholesterol under identical conditions.2.Analysis of the sterol composition of various segments of the small intestine and of the cecum of cholesterol-fed rats revealed the presence of appreciable amounts of coprostanol in the cecum, fourth and third quarters of the small intestine, and of small but measurable quantities in the first half of the small intestine.3.The quantity of cholic acid excreted through bile duct fistulas by a group of rats fed sucrose and lactose was found to be an average of 44.2 mg/24 hours and 75.3 mg/24 hours, respectively. The importance of the intestinal flora and the resulting effect on bile acid and cholesterol metabolism is discussed.

Streptomycin in the amounts of 0.4 to 4.0 μ/cc is bactericidal for different strains of P. pestis in 5 days. Advanced experimental bubonic plague in mice is completely cured with 500 μ/3 hours for 3 days, or a total of 120 mg. Between SO to 90% of the mice in a state of septicemic plague may be saved with a total of 1,200 to 1,600 μg. The remarkable bactericidal action of streptomycin is best demonstrated on experimental pneumonic plague; 5 mg of the antibiotic sterilize lungs and lymph nodes within 100 hours after treatment has been instituted. It is recommended that human plague be treated as soon as diagnosed with 2 to 4 g of streptomycin daily depending on the state of infection.

Ocular specimens, taken repeatedly from experimental trachoma in 2 rhesus monkeys, were cultured in parallel in McCoy cell cultures and in yolk sacs of embryonated eggs, to explore the feasibility of using the cell culture method of demonstrating virus as an aid in recognizing the infection. The results indicate a potential usefulness of the cell culture method in which the test can be read in 48 hours. When washing of the conjunctival sacs was compared with swabbing with dry cotton as a method of obtaining material for culture, the former procedure yielded a slightly greater number of positive tests. Bacteriologic studies on the specimens showed that the levels of streptomycin and ristocetin used in the cell cultures and yolk sacs satisfactorily protected against contamination by a variety of bacterial types.

1. Diffusion of mixed antigens from different sources in parallel directions in serum-agar gels was used for comparing the antigenic structure of 3 avirulent and 2 virulent strains of P. pestis.2. Merging of precipitation zones is a criterion of homology of antigens; crossing of zones is a criterion of heterology. By these criteria 3 groups among 5 strains of P. pestiswere established: Group I, Strains 195/P, Yreka, E. V. 76; Group II, Strain A1122; Group III, Strain 14.

BackgroundDimensions of the bony cochlear nerve canal (BCNC) have been proposed as a potential diagnostic standard for BCNC hypoplasia, but the standard remains inconsistent. Some studies have revealed that computed tomography virtual endoscopy (CTVE) with variation of reconstruction threshold is good at identifying labyrinthine fistulas or semi-circular canal dehiscence.PurposeTo examine diagnostic accuracy of VE in the evaluation of BCNC hypoplasia on basis of opening threshold.Material and MethodsTwenty ears diagnosed with BCNC hypoplasia were included in this study. One hundred ears served as controls. The opening thresholds were measured by two reviewers. Intraclass correlation coefficients (ICC) were reported. The width of BCNC was obtained on transverse CT images. Association between the width of BCNC and opening threshold was assessed by using Spearman correlation coefficients. ROC curves were applied to assess the best cut-off value of opening threshold.ResultsThe opening threshold of BCNC was significantly higher in diseased ears (926 ± 308 Hounsfield units [HU]) than that in control ears (287 ± 72 HU). Inter-observer agreement was very good. The mean width of BCNC for diseased ears and control ears were 0.83 ± 0.36 mm and 2.21 ± 0.35 mm, respectively. Significant negative linear correlation was found between opening thresholds and width of BCNC (Spearman coefficient, −0.768; P < 0.001). The area under the ROC curve was 0.981. The cut-off opening thresholds of 408 for differentiation between the two groups provided the best combination of sensitivity (85%) and specificity (94%).ConclusionThe VE with opening threshold may be an effective optional tool for prediction of hypoplasia of BCNC.

The isolation of a number of benzenoid and naphthalenic hydrocarbons from cigarette smoke condensate is described. The origins of these substances during combustion of tobacco are discussed.

The effect of graded doses of irradiation (cobalt-60) on the morphology of McCoy cells was analyzed, and 4,000 to 5,000 r was selected as a satisfactory dose for production of giant cells. The susceptibility of radiation-induced giant cells to chlamydial infection was compared with that of nonirradiated cells by using three strains of Chlamydia trachomatisand one of C. psittaci. Monolayers of giant cells were more susceptible than normal McCoy cells as indicated by (i) greater numbers of inclusions (four- to eightfold) per unit area of monolayer, (ii) larger inclusions (fourfold greater in area), (iii) higher infective titers (1 log or more greater) of harvested cells, and (iv) greater ease of promoting a second cycle of growth. Graded doses of irradiation were applied also to mouse fibroblast (L) cells, and a similar increase in susceptibility to chlamydial infection was noted. It is concluded that giant cells produced by irradiation possess advantages over nonirradiated cells in culture for growth of Chlamydia.