Replicate plating: does it increase reliability?

As a part of a clinical study to evaluate the antibacterial effect of a topically applied erythromycin gel, microbiological specimens were taken from two groups of patients: one group using 2% erythromycin gel and the other group using a placebo gel. These specimens were plated in triplicate using a common source on bacteriological media using standard procedures. After the appropriate incubation times, the numbers of aerobic and anaerobic organisms were counted separately from each of three plates. A comparison of the bacterial colony counts from the replicate plates showed a high degree of similarity for each type of organism. Tests for treatment differences in organism counts were performed based on single, double and triplicate plating. The results obtained were almost identical, suggesting that replicate plating from a common source is no more accurate than single plating. The only apparent advantage of this type of replicate plating is heightened confidence in the reliability of bacterial counts from single plates.

Acute postural change--a novel approach to blood pressure tracking in children.

Among 1443 children, aged 5 to 18, followed for five consecutive years, we identified 68 who tracked consistently in the lowest blood pressure (BP) quartile and 114 in the highest. BP and corresponding heart rate were taken with subjects in the supine, sitting and erect postures. BP quartiles were established for each height category. Children consistently in the highest BP quartile had greater relative weight and higher heart rates in all three positions. On assuming the erect posture, children in the lowest BP quartile showed an increase in systolic BP, while those in the highest BP quartile showed a decrease. Both groups showed an increase in diastolic BP. On assuming the erect posture, subjects in the two groups showed no difference in heart rate change; subjects in the highest BP quartile did not show the additional reflex increase in heart rate to be expected in response to the decrease in systolic blood pressure. This combination of BP and heart rate findings suggests a subtle change in the baroreceptor reflex.

Trends of lung cancer in northern Florida.

Although the entire state of Florida has experienced an increase in lung cancer mortality during the present decade, a differential rise among white men has been observed in Duval, a county in its northeastern region. This increase is not explained by population changes or migration of cases. It is hypothesized that an industrial exposure involving paper and pulp manufacturing, shipbuilding, or petroleum may account for these findings.

A comparison of growth: Spanish-surnamed with non-Spanish-surnamed children.

Weight, height, and head circumference measurements of 4,167 Spanish-surnamed school-aged children were compared with similar data from 2,322 non-Spanish surnamed children who resided in the same Denver, Colorado neighborhoods. These data were also compared with data from six other studies. Both male and female Spanish-surnamed children were found to weigh less, be shorter, and have smaller head circumferences than non-Spanish-surnamed children living in the same Denver neighborhoods. The sizes of the children in these two populations residing in lower and lower-middle class neighborhoods were closer to each other than to the sizes of children from middle and upper-middle socioeconomic classes as measured in previous studies or to the sizes of children in the recently published cross-sectional National Center for Health Statistics study. Such comparisons suggest that growth retardation is more a reflection of socioeconomic factors than of ethnic-genetic factors.

Effect of a physical conditioning program upon left ventricular ejection fractions determined serially by a noninvasive technique.

6 clinically normal subjects underwent a 3-month physical conditioning program with the ejection fractions determined before and after physical conditioning using a scintillation probe. All subjects achieved a conditioning effect as evidenced by increased treadmill test duration after conditioning (mean duration before conditioning: 658 vs. 715 sec after conditioning; p less than 0.02). All 6 subjects increased resting ejection fractions after conditioning (mean ejection fraction before conditioning: 54.5 +/- 5.4%; mean ejection fraction after conditioning: 67.0 +/- 9.0%; p less than 0.01). Thus, an aerobic physical conditioning program appears to increase resting ejection fractions in normal subjects.

Is the Autorefractor reading closest to manifest refraction? A comparison of the patient's previous spectacles and the 6600 Autorefractor reading.

In a study of 56 patients, the old glasses of a previously refracted individual were as close to the final subjective refraction as the reading obtained with a 6600 Autorefractor. Therefore, the previous spectacle correction might logically be used for the starting point of a subjective refraction, with retinoscopy or automatic refractor results being used for this purpose in patients whose previous spectacle refraction is unknown or in the first refraction of an aphakic patients.

Clinical evaluation of the 6600 Autorefractor.

The 6600 Autorefractor was evaluated on 200 patients undergoing refraction. The automatic refractor showed a high degree of accuracy in determining the needed refractive correction, but the errors are sufficient that the automatic refractor alone without subjective refinement cannot be substituted for conventional complete refracting methods with subjective refinement. However, for aphakic patients and for patients with clear media and cylindric corrections over 0.50 diopters, the automatic refractor can be used as a substitute for retinoscopy in determining the starting point for a subjective refraction.

Decreased serum cholesterol-binding reserve in diabetes mellitus.

Serum cholesterol-binding reserve (SCBR), the capacity of a serum sample to solubilize additional cholesterol in excess of its cholesterol content, was measured in 43 white male patients with maturity-onset diabetes in the age range of 35--59 years who were under treatment with insulin. The values were compared with those of 194 nondiabetic controls of the same race, sex, and age range. The mean +/- S.D. of SCBR of patients (71.9 +/- 29.3 mg./dl.) was lower than that of controls (88.9 +/- 30.9 mg./dl.) (p less than 0.001). Age in the range of 35 to 59 years had no correlation with SCBR in either patients or controls. SCBR was positively correlated with serum levels of cholesterol (SC) and triglycerides (TG) in both patients and controls. After adjustment for SC and TG, the difference in SCBR between patients and controls persisted (p less than 0.001). In 15 of 20 (75 per cent) patient-control pairs matched for SC and TG to within 5 per cent, the patient had lower SCBR (paired t-test, p less than 0.002). In 16 patients without elevation of serum lipid levels (SC below 250 and TG below 150 mg./dl.), the mean +/- S.D. of SCBR (59.1 +/- 17.7 mg./dl.) was lower than that of 49 controls having serum lipids in the same range (77.4 +/- 31.7 mg./dl.) (p less than 0.03). These results indicate an association of decreased SCBR with diabetes and are consistent with the hypothesis that low SCBR is associated with accelerated atherosclerosis and enhanced risk for coronary heart disease.

Long-term antiarrhythmic therapy in survivors of prehospital cardiac arrest. Initial 18 months' experience.

Ambulatory rhythm monitoring and chronic arrhythmia management were studied in 16 patients resuscitated from prehospital cardiac arrest. Asymptomatic complex ventricular arrhythmias (ACVA) occurred in 12 patients (75%) entering long-term follow-up during the first 12 months (average follow-up, 13.25 months). The patients' therapy consisted of a dose-adjusted, membrane-active antiarrhythmic drug regimen monitored by blood levels. While there has been little change in the frequency of ACVAs despite carefully controlled antiarrhythmic management, only one death has occurred during 212 patient-months of postarrest follow-up, a 6% one-year mortality. This compares favorably to our previous experience in survivors of prehospital cardiac arrest not receiving a controlled antiarrhythmic program. Despite the failure to suppress ACVAs, the drug-monitored population is showing a trend toward a decreased frequency of recurrent cardiac arrest.

Attack rates of acute nephritis after type 49 streptococcal infection of the skin and of the respiratory tract.

Prospective studies in a population of American Indian children during an outbreak of acute nephritis associated with the Type 49 Group A streptococcus permitted a comparison of attack rates of renal complications after infection at different sites and at different ages. Acute nephritis or unexplained hematuria developed in 10 of 42 children (23.8%) with Type 49 streptococcal skin infection, in 2 of 44 (4.5%) with Type 49 throat infection, and in 3 of 16 (18.8%) with simultaneous Type 49 infection at both sites. The higher attack rate of nephritis and hematuria in children with pyoderma indicates that skin lesions played a direct and quantitatively greater role than respiratory infection in the pathogenesis of acute nephritis during this outbreak. Skin infections with the Type 49 strain were followed by evidence of renal complications more often in children younger than 6.5 yr (9 of 21 or 43%) than in older children (1 of 21 or 5%). Attack rates of renal complications after Type 49 skin infection were approximately equal in males and females.