Colonial morphology of staphylococci on Memphis agar: phase variation of slime production, resistance to beta-lactam antibiotics, and virulence.

The growth of Staphylococcus epidermidis sensu stricto and Staphylococcus saprophyticus on Memphis agar yielded up to 6 morphotypes with each strain. With S. epidermidis, one morphotype produced slime (rho) but became non-slime-producing (epsilon) at a high frequency. The slime-producing rho variants were methicillin-resistant and more virulent than methicillin-susceptible epsilon variants in an endocarditis model. With S. saprophyticus, phase variation was of higher frequency. Nitrosoguanidine mutagenesis produced a stable blue epsilon form that was more virulent than the parent in a mouse model of urinary tract infection. Mutants with the blue epsilon phenotype differed from gold epsilon parents in a variety of phenotypic properties, including increased resistance to oxacillin. These staphylococcal species have a high frequency of phase variation: Phase variants differ in antibiotic resistance and virulence, which is only partially correlated with suggested virulence factors such as slime production.

Hemodynamic characteristics of sodium-sensitive human subjects.

Fifty-eight normal subjects and 51 subjects with borderline hypertension underwent microvascular and hemodynamic studies while on an ad libitum diet and during periods of sodium depletion (10 mEq/day) and repletion (200 mEq/day). Hemodynamic measurements included arterial blood pressure, cardiac index, total peripheral resistance, forearm blood flow, vascular resistance, venous compliance, and capillary filtration fraction. Studies of the microcirculation consisted of macrophotography of the bulbar conjunctiva with measurement of anteriolar, venular, and capillary density and diameter. During sodium repletion, cardiac index increased significantly in the normal subjects (2.35 +/- 0.7 vs 2.44 +/- 0.7 L/min/m2; p less than 0.01) and in the borderline hypertensive subjects (2.50 +/- 0.7 vs 2.70 +/- 0.8 L/min/m2; p less than 0.01). However, mean blood pressure rose by more than 5% in only 33 subjects, 13 with normal and 20 with borderline hypertension. When these sodium-sensitive subjects were compared with those whose blood pressure did not rise, the former were found to have significantly higher forearm vascular resistance (32.2 +/- 21 vs 17.9 +/- 12 mm Hg/ml/min/100 g; p less than 0.01), lower forearm blood flow (4.42 +/- 2.7 vs 7.47 +/- 5.0 ml/min/100 g) and lower conjunctival capillary density (3.72 +/- 1.7 vs 5.18 +/- 2.1 [SD] mm/mm2; p less than 0.05). These results indicate that sodium sensitivity in humans is accompanied by elevation of forearm vascular resistance and attenuation of the microcirculation.

Attenuation of the microcirculation in young patients with high-output borderline hypertension.

Previous studies have shown abnormalities of the microvasculature in the spontaneously hypertensive rat and human subjects with established hypertension. We have studied the conjunctival microvasculature in relation to systemic and forearm hemodynamics in 24 normal subjects (NL) and 10 subjects with intermittent elevation of blood pressure (BHT). Macrophotographs of the conjunctival circulation were measured for arteriolar diameter and density of arterioles, capillaries, and venules. Blood pressure was measured by Arteriosonde, cardiac index by echocardiography, and forearm hemodynamics by mercury-filled strain-gauge venous occlusion plethysmography. Average diastolic blood pressure in the NL group was 74 +/- 1.7 mm Hg, while that of the BHT subjects was 89 +/- 3.1 mm Hg (p less than 0.005). Capillary density, venous density, and total vascular density were significantly lower in the BHT than NL group, while arteriolar density did not differ significantly. Cardiac index was significantly higher, and peripheral vascular resistance significantly lower, in the BHT as compared to the NL subjects. Forearm blood flow was higher in the NL subjects. The diameter of the preterminal arterioles of the BHT subjects was 27% greater than NL (p less than 0.02). The capillary density was inversely related to the cardiac index (r = -0.482, p less than 0.01), but was not related to blood pressure (r = -0.207). We conclude that the high cardiac output phase of early essential hypertension in humans is accompanied by a reduction in the number of filtering capillaries, and that the rarefaction of capillaries is more closely related to the elevation of cardiac output than to raised blood pressure.

The effectiveness of low-strength anthralin in psoriasis. A paired comparison study.

Recent trends in psoriasis therapy favor using lower-strength anthralins. To assess the effectiveness of a low concentration (0.01%) v a mid concentration (0.1%) of anthralin, combined with UV-B therapy, a prospective double-blind study was undertaken. Nine patients with chronic plaque-type psoriasis involving more than 25% of the total body surface (excluding the scalp) were treated in a paired comparison manner. Patients were examined each day and the degree of erythema, induration, and scale of lesions was recorded for each side of the body. In all nine patients, the side receiving 0.1% anthralin required an average of 10.8 treatment days to achieve the predefined end point: complete flattening of all plaques to palpation. An identical rate of improvement for the 0.01% anthralin-treated side was noted in five of nine patients. The remaining four patients failed to reach the end point on the 0.01% anthralin-treated side even after an average of 15 treatment days.

Infrared photographic studies of rosacea.

Three patients with erythematotelangiectatic rosacea were examined using infrared photography. The vascular patterns in the malar areas of all the patients were completely obliterated in the photographs. A review of the results of infrared studies on other cutaneous vascular lesions indicates that the disorder in rosacea is not associated with the superficial, collecting veins.

Applied teaching concepts of animated motion slides in otolaryngology.

Motion is an essential part of otolaryngologic function, and an understanding of concepts of motion is critical in teaching otolaryngology. Standard movie projection devices have intrinsic defects, such as considerable expense to make, complexity of operation, and a lack of flexibility. Slide projection transparencies (2X2) offer instructional flexibility but could not be used to project motion until recently. Using applications of gelatin films of images with polarizing light, we have been able to produce an illusion of motion similar to that used in creating the motion in cartoons. We have produced a series of slides for instructional purposes to show concepts in otolaryngology.