Etiological heterogeneity in Hodgkin's disease: HLA linked and unlinked determinants of susceptibility independent of histological concordance

Forty-one multiplex families, from published sources and new data from the National Cancer Institute, segregating for Hodgkin's disease and HLA, have been studied. A reanalysis of these data strongly suggests a recessive mode of inheritance for susceptibility to Hodgkin's disease. The HLA haplotype sharing data between affected relatives demonstrate that approximately 60% of cases in multiplex families are due to an HLA-linked susceptibility gene, the remaining 40% being due to other familial factors. The data clearly support the hypothesis of etiological heterogeneity for Hodgkin's disease, with both HLA-linked and HLA-unlinked factors being responsible. Finally, there is an increased concordance of histological types between affected relatives, but this concordance seems independent of HLA sharing.     

Magnetic resonance imaging of the brain in childhood herpesvirus infections

We used magnetic resonance imaging (MRI) to evaluate nine children with neurologic disorders caused by infections with members of the herpesvirus family. MRI studies were abnormal in eight children and demonstrated a wide range of central nervous system lesions, including cystic encephalomalacia, ventricular enlargement, cerebral atrophy and focal parenchymal lesions. When compared with conventional computed tomographic scanning, MRI was more sensitive in detecting abnormalities of white matter and in defining the extent of parenchymal lesions. These studies indicate that MRI scans are highly useful in children with herpesvirus infections involving the central nervous system.     

Xerophthalmia caused by self-induced deficiency

The case is described of a 36 years old woman with bilateral xerophthalmia secondary to his diet. She presented a perforation of the left cornea which required an emergency penetrating keratoplasty. The treatment is described.     

Evidence against the practicality and cost-effectiveness of a gram-positive coccal selective plate for routine urine cultures.

A total of 899 urine cultures were evaluated to assess the need for and cost-effectiveness of using a gram-positive coccal selective plate in the initial plating of urine cultures. Of these cultures, 437 were examined retrospectively and 462 were examined prospectively. Urines were quantitatively plated to three media: sheep blood sugar, MacConkey agar, and phenyl ethyl alcohol agar. Of all urine samples in both studies, 52% yielded no growth on any of the three media. Of all 899 urine cultures, there were only 5 cultures (less than 1%) in which a significant count of a gram-positive organism was detected only on the phenyl ethyl alcohol agar plate and not recoverable on the sheep blood agar plate. In each of these five instances, the need for the use of the selective plate occurred when a Proteus mirabilis strain swarmed over an enterococcus. The inclusion of a selective gram-positive coccal medium for initial plating of urine cultures is unnecessary and not cost-effective. When Proteus swarms on sheep blood agar, a sweep should be made with an inoculating loop from the sheep blood agar and streaked to phenyl ethyl alcohol agar or a similar gram-positive coccal selective medium.     

Teratomas in childhood.

Of 107 teratomas in children, 86 were benign and 21 malignant. Sacrococcygeal and pelvic teratomas predominated (51 cases) and these fell into 3 groups: post sacral, dumb-bell and presacral. The 34 purely posterior tumours were always congenital and benign, whilst the incidence of malignancy in dumb-bell and presacral teratomas increased as the tumour became more internal. Malignant teratomas were carcinomas, usually containing glandular, papillary and clear-cell areas, and metastases were similar. Immature tissues in benign teratomas were usually neural or connective tissue. They did not give rise to neuroblastomas or sarcomas, and did not indicate a worse prognosis. Only 2 originally benign teratomas later developed malignancy.     

Prospective evaluation of the Gen-Probe assay for detection of Legionellae in respiratory specimens

A prospective evaluation of a DNA probe assay for detection ofLegionella species was performed on 427 consecutive respiratory specimens submitted over an 18-month period. The Gen-Probe assay utilizing both low (4.0) and high (>7.0) ratio threshold values was compared to direct fluorescent antibody staining (DFA) as a predictor of isolation ofLegionella on culture. The highest sensitivity (63 %) was obtained with the lower threshold ratio, but was not significantly different from the result obtained with a threshold ratio of >7.0 (50 %, p=0.722) or DFA results (44 %, p=0.479). The specificity of the DNA probe assay was improved with the high threshold (99 %) compared either to the low threshold ratio (95 %, p=0.0002) or DFA (97 %, p=0.055). When the DNA probe was compared to DFA and/orLegionella isolation on culture, a significantly lower specificity (97 % versus 99 %, p=0.0006) and higher sensitivity (74 % versus 37 %, p=0.013) was obtained with a threshold value of 4.0 than >7.0. Ten of 20 specimens with a DNA probe ratio between 4.0 and 7.0 were DFA positive, although only two were isolated on culture. The DFA assay and both probe threshold ratios have a high negative predictive value when compared to culture. However, only the threshold ratio of >7.0 has a sufficiently high positive predictive value to be useful alone. Although the DNA probe appears to be a practical alternative to DFA testing for the rapid diagnosis ofLegionella infections, false-negative results emphasize the importance of obtaining several specimens for testing, and confirm the fundamental role of culture in the diagnosis ofLegionella infections.     

The spot indole test for identification of swarming Proteus

The authors evaluated the use of the spot indole test for rapid speciation of swarming Proteus from the primary isolation plate. One hundred seventy-two consecutive isolates of swarming Proteus were studied, 163 Proteus mirabilis and nine Proteus vulgaris. One hundred fifty-six isolates (95.7%) of Proteus mirabilis gave a negative spot indole. Seven (4.3%) gave a positive spot indole test, but all seven isolates were from cultures in which other indole-producing organisms also were present. If only isolates representing single gram-negative strains in the specimens were tested, the predictive value was greater than 99%. Eight of the nine (88.9%) Proteus vulgaris isolates gave a positive spot indole test; one (11.1%) gave a negative result. This isolate also failed to produce indole by conventional methods but was ornithine decarboxylase negative, and additional biochemical testing was consistent with the Proteus vulgaris identification. All Proteus vulgaris isolates were resistant to ampicillin, and 94.2% of the Proteus mirabilis tested were ampicillin susceptible. The spot indole test is a rapid, accurate, simple, and cost-effective means of speciating swarming Proteus strains isolated as the only gram-negative bacilli in a specimen. The spot indole test should be used in conjunction with an ampicillin susceptibility test result or other confirmatory test information if other gram-negative bacilli are present in the culture.     

Time-motion and cost comparison study of micro-ID, API 20E, and conventional biochemical testing in identification of Enterobacteriaceae.

A total of 730 Enterobacteriaceae strains isolated from 567 cultures were evaluated by a rapid kit method (Micro-ID; General Diagnostics, Morris Plains, N.J.; 4 h), an overnight incubation kit method (API 20E; Analytab Products, Plainview, N.Y.), and conventional biochemical test methodology (mostly overnight incubation and some rapid methods) to compare the amount of laboratory effort required, timing, and cost parameters. We assessed the amount of technologist time expended, the time sequence of culture reporting to physicians, the number of isolates requiring repeat testing or additional biochemical testing, the number of cultures held due to the need for identification of other organisms, the cost of total work-up, etc. Cultures evaluated included urines, respiratory cultures, wound cultures, body fluids, genital cultures, and cultures from miscellaneous categories. A total of 64% of the Enterobacteriaceae strains processed by the Micro-ID method could be identified within 24 h of receipt of the specimens in the clinical laboratories, in contrast to the need for an additional day required by the API or conventional biochemical methods. The Micro-ID method also required less technologist time (4.5 min) for set-up and interpretation than did either the API method (6 min) or conventional methods (7 min). Total direct costs (June 1981) per organism identified were: Micro-ID, $4.30; API 20E, $4.96; conventional biochemicals with commercially prepared media, $5.66. An estimate of 80% technologist time efficiency was made in all procedures.