Childhood medulloblastoma in Ontario, 1977-1987: population-based results

A retrospective review was carried out to study children, not more than 16 years old, with a confirmed diagnosis of medulloblastoma, who were residents of the Province of Ontario at the time of diagnosis between 1977 and 1987 inclusive. The provincial tumour registry provided the population database. One hundred and eight children with medulloblastoma were identified of whom 72 (67%) were initially treated at University of Toronto Centres and 36 (33%) at other Health Science Centres, hospitals, and Regional Cancer Centres (RCC) in Ontario. The hospital/Cancer Centre records were reviewed. The 5-year relapse-free survival (RFS) for all patients treated in Ontario was 58% (SE = 5%). Those treated in Toronto had a 5-year RFS of 65% (SE = 6%) compared to 44% (SE = 8%) for those treated in other RCCs in the province (P = 0.02). Relapse-free survival for the RCCs ranged from 25 to 60%, with a trend for improved survival with increasing centre size. Univariate analysis of determinants of relapse-free survival for all 108 patients showed the following variables to be significant: T-stage (Tx + T1 + T2 vs. T3A + T3B) P = 0.0004, M-stage (M0 + Mx vs. M1-4) P = 0.0006, extent of resection (total vs. less than total) P = 0.002, radiotherapy (craniospinal irradiation and posterior fossa boost vs. other) P = 0.02, and treatment centre (Toronto centres vs. RCC) P = 0.02. Cases treated at centres outside metropolitan Toronto had a nearly two-fold (relative risk = 1.93; 95% confidence interval = 1.07, 3.47) greater risk of recurrence or death than those seen in Toronto. However, in multivariate analysis this difference was not quite significant (P = 0.07) after controlling for stage (T and M), extent of resection, meningitis, and gender. These data suggest that patients with medulloblastoma should be referred for treatment to large centres with major pediatric neurosurgical and oncology resources.

The molecular chaperone function of alpha-crystallin is impaired by UV photolysis

Buffer solutions of the lens protein gamma-crystallin and the enzymes aldolase and liver alcohol dehydrogenase became turbid and formed solid precipitate upon exposure to an elevated temperature of 63 degrees C or to UV radiation at 308 nm. When alpha-crystallin was added to the protein solutions in stoichiometric amounts, heat or UV irradiation did not cause turbidity, or turbidity developed much less rapidly than in the absence of alpha-crystallin. Hence, normal alpha-crystallin functioned as a "molecular chaperone," providing protection against both UV and heat-induced protein aggregation. When alpha-crystallin was preirradiated with UV at 308 nm, its ability to function as a chaperone vis-a-vis both UV and heat-induced aggregation was significantly impaired, but only at relatively high UV doses. A major effect of preirradiation of alpha-crystallin was to cause interpeptide crosslinking among the alpha A2 and alpha B2 subunits of the alpha-crystallin macromolecule. In our experiments alpha-crystallin was exposed to UV doses, which resulted in 0.50 and 90% crosslinking as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. alpha-Crystallin samples that were 50% and 90% crosslinked gave chaperone protection, which was increasingly impaired relative to unirradiated alpha-crystallin. The results are consistent with the notion that UV irradiation of alpha-crystallin results in loss of chaperone binding sites.

Quantitative measures of human immunodeficiency virus-specific antibodies predict progression to AIDS

Studies examining specific antibodies directed against antigenic components of human immunodeficiency virus (HIV), as potential markers of progression to AIDS, have reported inconsistent results. We used reflectance densitometry and survival analysis to determine whether single quantitative measures of HIV-specific antibodies predicted progression to AIDS in a prospective cohort of 159 HIV-infected homosexual men. Lowered baseline levels of p24 antibody and p24/gp41 antibody ratio were independent predictors of progression to AIDS and retained statistical significance after simultaneously controlling for CD4:CD8 ratio, age, use of zidovudine, and clinical symptoms. Quantitative measures of p24 antibody and p24/gp41 antibody ratio warrant further study with regards to their clinical application as markers of HIV disease progression.

Signaling by ABL oncogenes through cyclin D1

Oncogenic signals induce cellular proliferation by deregulating the cell division cycle. Cyclin D1, a regulator of G1-phase progression, acts synergistically with ABL oncogenes in transforming fibroblasts and hematopoietic cells in culture. Synergy with v-Abl depended on a motif in cyclin D1 that mediates its binding to the retinoblastoma protein, suggesting that ABL oncogenes in part mediate their mitogenic effects via a retinoblastoma protein-dependent pathway. Overexpression of cyclin D1, but not cyclin E, rescued a signaling-defective src-homology 2 (SH2) domain mutant of BCR-ABL for transformation of cells in culture and malignant tumor formation in vivo. These results demonstrate that cyclin D1 can provide essential signals for malignant transformation in concert with an activated tyrosine kinase.

Alternative signals to RAS for hematopoietic transformation by the BCR-ABL oncogene

Biological function of the BCR-ABL oncogene is dependent on its activated tyrosine kinase. Mutations that inactivate the SRC homology 2 (SH2) domain, the GRB2-binding site in BCR, or the major autophosphorylation site of the kinase domain selectively disrupt downstream signaling but not tyrosine kinase activity. Despite a loss of fibroblast transformation activity, all three mutants retain the ability to render hematopoietic cell lines growth factor independent and transform primary bone marrow cells in vitro. In vivo tests of malignant potential reveal a most critical role for signals dependent on the BCR-ABL SH2 domain. The efficiency of both fibroblast and hematopoietic transformation by BCR-ABL is strongly affected by increased dosage of the SHC adapter protein, which can connect tyrosine kinase signals to RAS. The BCR-ABL oncogene activates multiple alternative pathways to RAS for hematopoietic transformation.

Comparative antimicrobial activities of the penem WY-49605 (SUN5555) against recent clinical isolates from five U.S. medical centers

The in vitro activity of WY-49605 (SUN5555) (WY) was compared with those of cefaclor, cefixime, and amoxicillin-clavulanic acid against 2,958 consecutive clinical isolates from five medical centers and 402 respiratory pathogens from 18 other facilities. Most members of the family Enterobacteriaceae were inhibited by WY (MIC at which 50% of the isolates are inhibited [MIC50], < or = 2.0 micrograms/ml). MIC90s of > or = 8.0 micrograms/ml were observed for Enterobacter cloacae, Serratia spp., and Proteus mirabilis. WY was the most active drug against methicillin-susceptible Staphylococcus aureus (MIC90, 0.12 microgram/ml) and other coagulase-negative staphylococci (MIC90, 4.0 micrograms/ml). The four drugs were not active against nonenteric gram-negative bacilli, methicillin-resistant Staphylococcus aureus, and Staphylococcus haemolyticus. At 2.0 micrograms/ml, WY inhibited 82% of Enterococcus faecalis strains and was equal to or superior to the other drugs against streptococci, Haemophilus influenzae, and Moraxella catarrhalis.

Genetic requirement for Ras in the transformation of fibroblasts and hematopoietic cells by the Bcr-Abl oncogene

To determine the functional importance of Ras in transformation by Abl oncogenes, we used a genetic approach to measure the effect of impaired Ras activity on the ability of Bcr-Abl or v-Abl to transform cells. Expression of the catalytic domain of the GTPase activating protein for Ras (Gap C terminus) impaired soft agar colony formation by fibroblasts expressing v-Abl or Bcr-Abl by 70-80%. To test Ras function in a model that more closely resembles clinical diseases involving Bcr-Abl, double gene retroviruses expressing Bcr-Abl paired with the Gap C terminus or dominant negative Ras were introduced into naive mouse bone marrow cells. Transformation by Bcr-Abl was completely blocked in both situations. Coexpression of normal c-H-Ras accelerated the transforming activity of Bcr-Abl. These findings show that Ras activation is essential for the leukemogenic activity of Abl oncogenes in two distinct model systems. The results genetically define a connection between the Bcr-Abl cytoplasmic tyrosine kinase and Ras and add to the accumulating evidence that deregulation of Ras is a central event in the genesis of a number of molecularly distinct forms of human myeloid leukemia.

Interpretive criteria and quality control for antimicrobial susceptibility tests of levofloxacin

To confirm preliminary interpretive breakpoints for prototype 5 micrograms levofloxacin disks, 490 strains were tested in vitro using commercially manufactured disks. For in vitro susceptibility testing, 5 micrograms levofloxacin disks can be used with interpretive criteria of < or = 12 mm for resistant (MIC > or = 8.0 micrograms/ml) and > or = 16 mm for susceptible (MIC < or = 2.0 micrograms/ml). Proposed quality control limits for tests of levofloxacin are as follows: Escherichia coli ATCC 25922, zones 29-37 mm or MIC 0.008-0.03 microgram/ml; Pseudomonas aeruginosa ATCC 27853, zones 19-26 mm or MIC 0.5-2.0 micrograms/ml; Staphylococcus aureus ATCC 25923, zones 24-31 mm; Staphylococcus aureus ATCC 29213, MIC 0.06-0.25 microgram/ml and Enterococcus faecalis ATCC 29212, MIC 0.25-2.0 micrograms/ml.

Differential complementation of Bcr-Abl point mutants with c-Myc

A complementation strategy was developed to define the signaling pathways activated by the Bcr-Abl tyrosine kinase. Transformation inactive point mutants of Bcr-Abl were tested for complementation with c-Myc. Single point mutations in the Src-homology 2 (SH2) domain, the major tyrosine autophosphorylation site of the kinase domain, and the Grb-2 binding site in the Bcr region impaired the transformation of fibroblasts by Bcr-Abl. Hyperexpression of c-Myc efficiently restored transformation activity only to the Bcr-Abl SH2 mutant. These data support a model in which Bcr-Abl activates at least two independent pathways for transformation. This strategy may be useful for discerning signaling pathways activated by other oncogenes.

The nuclear tyrosine kinase c-Abl negatively regulates cell growth

c-Abl is a tyrosine kinase localized primarily in the nucleus. Previous assays for abl function rely on cellular transformation by abl mutants, which are cytoplasmic. Using a conditional overexpression strategy, we have developed a functional assay for c-abl. Overexpression of c-abl inhibits growth by causing cell cycle arrest. Growth suppression requires tyrosine kinase activity, nuclear localization, and an intact SH2 domain. Overexpression of dominant negative c-abl disrupts cell cycle control and enhances transformation by tyrosine kinases, G proteins, and transcription factor oncogenes. These findings suggest that c-abl acts as a negative regulator of cell growth. This growth suppressive activity is functionally similar to that of tumor suppressor genes such as p53 and Rb.

Outbreak of Hantavirus pulmonary syndrome in the southwestern United States. Response of pathologists and other laboratorians

During late spring and early summer of 1993, national and international media called worldwide attention to a cluster of deaths in the southwestern United States. These patients succumbed to a rapidly progressive severe respiratory distress syndrome. After notification of state and national health agencies in mid-May, a major effort was launched to determine the cause of this often fatal respiratory distress syndrome, to advise the public on safety measures, and to determine the method of spread of this "mystery illness." Within weeks of recognition of the early cases, the Centers for Disease Control and Prevention announced the probable agent, a Hantavirus. This report details the response of pathologists, medical technologists, and other laboratory scientists to this new viral epidemic, with emphasis on activities that occurred within New Mexico.

Portable cardiac mapping assessment of acute ischaemic injury

A portable cardiac mapping system is used to improve the accuracy of diagnosis of acute ischaemic injury outside hospital. Patients presenting chest pain suggestive of myocardial infarction (MI) were mapped by attendant medical personnel operating from a mobile coronary unit. These first MI maps were compared against average normal maps using QRS and ST-T isointegral values. Discriminant function analysis performed on the parameters achieved a sensitivity of 90% and a specificity of 96%.

Women with cerebral palsy: obstetric experience and neonatal outcome

The aim of the study was to provide a preliminary basis for advising women with cerebral palsy (CP) who choose to initiate pregnancy regarding the course of parturition and the outcomes for their newborn infants. The authors studied 22 women with CP who had 38 pregnancies at a mean age of 26 years. Eight pregnancies were electively terminated and two resulted in miscarriage. Of the 28 viable pregnancies, one resulted in a preterm stillborn infant and two in preterm liveborn infants. Delivery was vaginal in 18 cases and by cesarean section in nine (one pregnancy was lost to follow-up). Pregnancy outcomes were reassuringly normal in this small, select sample of women with relatively mild CP. Possible effects of pregnancy and childbirth on general adaptive skills or specific child-care skills of women with CP could not be assessed in this retrospective study.

Staphylococcal septicaemia after endometrial destruction

Two cases of staphylococcus aureus septicaemia secondary to endometritis following endometrial destruction are presented. After surgical endometrial destruction, endometritis has been reported rarely, but there are no previous reports of staphylococcal septicaemia.

Self-care and multiple sclerosis: a view from two cultures

The role of self-care in the management of chronic illnesses is essential to successful patient care. This paper compares and contrasts self-initiated self-care practices of 51 Danish and 35 American persons with multiple sclerosis at various levels of disability. Respondents were asked about ways they managed their symptoms and problems during periods of non-medical contact--including methods of following the medical regimen; alternative treatments; use of lay-referral systems; and, sources of information regarding physical, psychological, social, and environmental dimensions of coping with the illness. The two groups of respondents varied regarding adaptation strategies and primary sources of information used. The ultimate aim, however, of using these strategies was similar; to gain control over uncertainty, dependency, and physical and emotional decline. This study suggests that the empowering role of self-initiated self-care strategies in chronic illness may transcend differences in health care systems.

Oncogenic activation of c-ABL by mutation within its last exon

The c-ABL proto-oncogene is a predominantly nuclear localized tyrosine kinase. A random mutagenesis scheme was used to isolate c-ABL mutants whose expression produced a transformed phenotype in rodent fibroblast cells. An in-frame deletion within the central region of the last exon was identified in one ABL mutant. The mechanism of c-ABL oncogenic activation by mutation within the last exon differs both functionally and structurally from those of v-ABL and BCR/ABL. This class of ABL mutants shows increased tyrosine phosphorylation of cellular proteins in vivo but low levels of autophosphorylation. Last-exon ABL mutants are distinguished from v-ABL or BCR/ABL by their inability to transform primary bone marrow cells or support the growth of transformed pre-B cells. These findings define a new mechanism of oncogenic activation for the ABL kinase through mutations in the last exon which do not require amino-terminal deletions or mutations within the src homology regions.

Ampicillin-sulbactam susceptibility testing criteria

In vitro studies in five different medical centers documented the susceptibility of 2,440 consecutive isolates of the Enterobacteriaceae against ampicillin-sulbactam disks of different potencies. For determination of MICs, both 2:1 or 1:1 ratios were used as long as the concentrations of sulbactam at the breakpoints remained the same, i.e. MIC < or = 16/8.0 micrograms/ml or < or = 8.0/8.0 micrograms/ml for the susceptible category. Disks containing 10 micrograms of ampicillin and 10 micrograms of sulbactam are still to be preferred with interpretive criteria of > or = 15 mm for susceptible and < or = 11 mm for resistant (MIC > or = 64/32 micrograms/ml or > or = 32/32 micrograms/ml). The reliability of the disk test actually diminished when the amount of sulbactam in the disk was increased.

The sensory neuropathy of Friedreich's ataxia: an autopsy study of a case with prolonged survival

Observations have been made on a patient with Friedreich's ataxia who died 52 years after the onset of symptoms. The pathology of the brain and spinal cord was typical of this disorder. Apart from loss of dorsal root ganglion cells, severe loss of secondary sensory neurons was observed, including the nucleus dorsalis in the spinal cord, the spinal and principal trigeminal nuclei and, in particular, the mesencephalic trigeminal nucleus in the brain stem. Morphometric studies on the first sacral nerve root and on the sural nerve at levels from midthigh to ankle revealed a distally accentuated axonal loss that predominantly affected larger myelinated nerve fibres. Regenerative activity was seen, mainly in the spinal root and proximally in the sural nerve. Relative myelin thickness, assessed by a g ratios, tended to be reduced. As teased fibre studies showed only limited evidence of demyelination/remyelination and of axonal regeneration, this therefore suggests the presence of a hypomyelination. The results confirm the presence of a distal axonopathy and provide no evidence that this is preceded by axonal atrophy.