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Biomedical subjects

L Becker

Publications and source records attributed to L Becker.

At least 127 records · Page 7Linked to original sources
PubMed1990

Posterior fossa medulloblastoma in childhood: treatment results and a proposal for a new staging system.

Seventy-two children with posterior fossa medulloblastoma were diagnosed at the Hospital for Sick Children, Toronto, from 1977 to 1987 and treated by standard methods. The 5- and 10-year survival and disease-free survival rates were 71% and 63%, and 64% and 63%, respectively. Total tumor resection, as determined by the surgeon was the most significant favorable prognostic factor. Post-operative meningitis, a residual enhancing mass lesion on the post-operative, pre irradiation CT scan and dissemination to the brain or cord at diagnosis were unfavorable factors. These four easily definable factors were used to define a staging system with prognostic significance. Five-year disease-free survival rates were for Stage I (total resection, no adverse factor) 100%, Stage II (total resection with one or more adverse factor or less than total resection with no other adverse factor) 78%, and Stage III (less than total resection with one or more adverse factor) 18%. Evaluation of treatment results in medulloblastoma requires that these prognostic factors be known.

Adolescent↗
PubMed1990

Three-dimensional morphometry of mammalian cells. II. Areas, volumes, and area-volume ratios.

From three-dimensional diameter measurements of eleven kinds of cells pertaining to five different organs, which were excised from eleven adult mammals (nine species) whose body weight range was 40 g to 450 kg, we calculated the corresponding cell soma areas (A), volumes (V), and finally their area-volume ratios (A/V). The dissimilarities among these eleven cell types could be established quantitatively by means of a cluster analysis. The dendrograms for cell areas (A), volumes (V), and their corresponding area-volume ratios (A/V), yielded similar groupings when cell areas and volumes were compared, yet the grouping of the area-volume ratios (A/V) for the eleven types of cells was different. These results were corroborated by means of the principal components analysis, where five distinct cell groupings could be established. The relationship between cellular morphometry, oxidative metabolism, and body mass, was established by means of the fractal geometry of the transport systems (respiration and circulation), which provides the tools for the scale-dependent analysis of the surfaces across which the transport of metabolites is performed.

Animals↗
PubMed1990

Cervical spine injuries in children.

Cardiorespiratory arrest occurring immediately after multiple injuries is usually assumed to be due to severe cerebral injury, acute hemorrhage, or airway obstruction. We have identified a group of 19 children (mean age, 6.3 years) who presented with absent vital signs (VSA) or severe hypotension, unexplained by blood loss, where these findings were caused by injury to the high cervical spine and cord, demonstrated either by X-ray or postmortem examination. Fourteen had radiologic evidence of injury to the spine between C1 and C3. In two patients the bony injury was at the C6-7 level, while in two patients the cervical spine X-ray was normal. Eighteen of the 19 children were initially resuscitated but died from a combination of hypoxic/ischemic encephalopathy and cerebral injury. Sixteen patients underwent postmortem examination and in 13 there was evidence of cord laceration, up to and including cord transection. These findings demonstrate a distinct pattern of "juvenile" cervical spine injury involving the high spine and cord which results in either apnea and cardiorespiratory arrest, or severe hypotension. This previously unrecognized cause of cardiorespiratory arrest should be considered in all children presenting with VSA after multiple trauma, even when there is no apparent radiologic abnormality of the cervical spine.

Adolescent↗
PubMed1989

Down's syndrome individuals begin life with normal levels of brain cholinergic markers.

We measured the activities of the cholinergic marker enzymes choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) in autopsied brains of seven infants (age range 3 months to 1 year) with Down's syndrome (DS), a disorder in which virtually all individuals will develop by middle age the neuropathological changes of Alzheimer's disease accompanied by a marked brain cholinergic reduction. When compared with age-matched controls cholinergic enzyme activity was normal in all brain regions of the individuals with infant DS with the exception of above-normal activity in the putamen (ChAT) and the occipital cortex (AChE). Our neurochemical observations suggest that DS individuals begin life with a normal complement of brain cholinergic neurons. This opens the possibility of early therapeutic intervention to prevent the development of brain cholinergic changes in patients with DS.

Acetylcholinesterase↗
PubMed1989

MR imaging of the knee in the sagittal projection: comparison of three-dimensional gradient-echo and spin-echo sequences.

Fifty patients with suspected internal derangement of the knee had arthroscopic examinations after MR imaging with both a standard T1-weighted spin-echo (SE) sequence and a three-dimensional (3-D) gradient-echo sequence. This series permitted correlative evaluation of 100 menisci and 50 anterior cruciate ligaments. Meniscal tears were diagnosed when intrameniscal signal communicated with the meniscal surface. Criteria for diagnosing anterior cruciate ligament disruption included absence or discontinuity of the ligament, ligamentous laxity, and hyperflexion of the posterior cruciate ligament. Arthroscopic surgery confirmed the presence of 39 meniscal tears and 11 anterior cruciate ligament tears in this population. The sensitivity and specificity of the SE sequence for the diagnosis of meniscal tears were 77% and 98%, respectively. The 3-D gradient-echo sequence had a sensitivity of 87% and a specificity of 88%. For disruption of the ligament, the SE technique had a sensitivity of 82% and a specificity of 95% and the 3-D technique had a sensitivity of 64% and a specificity of 100%. Although these differences in sensitivity and specificity are not statistically significant at the p less than .05 level, probably because of the small sample size, the results show the relative strengths and weaknesses of the two imaging sequences. These data suggest that because of the complementary results of the two MR techniques, both the SE and the 3-D gradient-echo sequences have a role in the diagnosis of knee injuries.

Arthroscopy↗
PubMed1989

Three-dimensional morphometry of mammalian cells. I. Diameters.

Three-dimensional measurements of eleven kinds of cells, obtained from serial sections of five different organs, excised from eleven adult mammals of different body sizes-from a 40 g mouse to a 450 kg cow-were made. In order to minimize technical errors all organs were submitted to standardized fixation and staining procedures. Twenty cell diameters (at the nuclear level) were measured in each of the 7 microns serial tissue section which were made in two planes, after a 90 degree rotation of the fixed and embedded organ specimens. The mean values of the cell diameter measurements were submitted to a cluster analysis by means of a computer program, to establish the cell type groups with similar morphometric characteristics. The dendrograms of the cell-type groupings were then compared with the results obtained by applying the traditional statistical analysis of the cell sizes (in micrometers) in the three dimensions of space, and also with the principal component analysis. With the three statistical methods we came to analogous conclusions. The empirical allometric exponents for the three cell diameters, when expressed independently as functions of body mass, are not significantly different from zero, and in consequence cell sizes are independent of body mass. The physiological meaning of the body-size-independence of the mean three cell diameters is discussed.

Animals↗
PubMed1988

Brain neurotransmitters in glycine encephalopathy.

We measured neurotransmitter markers in autopsied brain of infants with glycine encephalopathy (GE). Because patients with GE develop intractable seizures, special attention was devoted to those neurotransmitter systems implicated in human epilepsy. Mean levels of glycine in the frontal cortex of GE patients were three times higher than control values. No abnormalities were observed for concentrations of gamma-aminobutyric acid (and related receptors), other major neurotransmitter amino compounds, or activities of cholineacetyltransferase and aspartate aminotransferase. Mean acetylcholinesterase activity was significantly elevated by 46%. As experimental data suggest, glycine markedly potentiates the action of the excitatory neurotransmitter glutamic acid. To the extent that the brain seizures in patients with GE can be explained by this mechanism, pharmacotherapy with excitatory amino acid antagonists may represent a new approach to the treatment of GE.

Amino Acid Metabolism, Inborn Errors↗
PubMed1988

Patients with new headache in primary care: a report from ASPN.

From a consecutive series of 3,847 headache patients, 1,331 patients who made first visits for new headache to 120 primary care physicians were studied for usual care over a 14-month period. Either tension or vascular headache was the initial diagnosis in 23.8 percent and 12.8 percent of patients, respectively. Nearly one half (47.8 percent) were classified as having headaches other than tension or vascular. A total of 15.3 percent of headaches were undiagnosed or were regarded as a mixture of traditional diagnostic designations. At first visit, most patients (76.6 percent) were managed without diagnostic tests. Drugs were prescribed for 73.6 percent, and advice was given for 58.6 percent. Only 2.0 percent of patients had computerized tomographic scanning ordered at first visit, although at least 46 percent met National Institutes of Health criteria, a finding with potential economic consequences of at least $2 billion. These findings suggest the need for reevaluation of diagnostic categories for headache, reevaluation of strategies for headache management, and further investigations of headache in primary care patients.

Headache↗
PubMed1987

Calcium deposits on CSF shunts. Clinical observations and ultrastructural analysis.

CSF shunts removed from seven patients 5-12 years after placement were studied. Examination in each case revealed gritty mineral deposits adherent to the external surface. The deposits were further analyzed by routine histology, spectroscopy and scanning electron microscopy. These results and the clinical consequences of this calcification are discussed. Microdefects in the tubing may contribute to delayed calcification of Silastic shunt tubing.

Calcinosis↗
PubMed1987

Clinical presentation of mitochondrial respiratory chain defects in NADH-coenzyme Q reductase and cytochrome oxidase: clues to pathogenesis of Leigh disease.

Measurement of pyruvate and lactate produced from glucose by confluent skin fibroblast cultures from 95 patients with lactic acidemia revealed 10 in whom the lactate/pyruvate ratio (L/P) was increased (L/P = 57 to 232) compared with that observed in control cell lines (L/P = 18 to 35). Mitochondria prepared from these cells revealed two types of respiratory chain defect. In four patients the deficient activity was present in NADH-coenzyme Q reductase (14% to 21% of controls), and in six the deficiency was in cytochrome c oxidase (21% to 28% of controls). The four patients with NADH-coQ reductase deficiency presented early with lactic acidosis, respiratory failure, anorexia, and hypotonia; all four died within 7 months. The group with cytochrome oxidase deficiency had a somewhat later (18 months to 2 years of age) presentation with milder lactic acidemia, but also with hypotonia and anorexia. They had delayed development, beginning to walk and talk at 18 to 24 months, and then slowly regressed. Although an investigation of central nervous system disorders in this latter group has not been possible, the clinical progression fits into the broad category of Leigh disease. We conclude that in these two groups respiratory chain defects can be detected and localized by the use of skin fibroblast cultures.

Brain Diseases, Metabolic↗
PubMed1987

Prophylactic antiarrhythmic therapy of high-risk survivors of myocardial infarction: lower mortality at 1 month but not at 1 year.

To determine whether prophylactic antiarrhythmic therapy influences mortality in high-risk patients after acute myocardial infarction, 143 such patients were randomized in a double-blind individually dose-adjusted, placebo-controlled trial an average of 14 +/- 7 days after myocardial infarction and followed for 1 year. Patients were judged to be at high risk on the basis of (1) ejection fraction less than 40% (n = 60), (2) arrhythmias of Lown class 3 or higher (n = 26), or (3) both (n = 57). Aprindine was chosen because of its long half-life, few side effects, and antiarrhythmic efficacy. Baseline characteristics in the treatment arms did not differ. Holter-detected arrhythmias were reduced in aprindine-treated patients at 3 months (p less than .001) and at 1 year (p less than .001). One patient was lost to follow-up; in the remaining patients 1 year mortality was 20% (28/142; 12 aprindine and 16 placebo). There was no significant difference between the two study arms in overall mortality and sudden death. However, among those who died, median duration of survival was longer in aprindine-treated patients (86 vs 21.5 days) (p = .04). Although antiarrhythmic treatment with aprindine of high-risk patients after myocardial infarction does not affect 1 year survival, mortality appears to be delayed; thus there may be a role for short-term treatment before more definitive therapy such as surgery.

Aprindine↗
PubMed1985

[Differential diagnosis of cystic intra-abdominal lesions: mucocele of the appendix].

The sonographic appearance of a mucocele of the appendix in a 69-year-old woman is presented. The mucocele showed an atypical localisation in the right upper quadrant just below the gallbladder. This own observation is compared with other case reports in the literature. The value of ultrasound examinations in the diagnosis "mucocele of the appendix" is discussed.

Aged↗
PubMed1984

The Ambulatory Sentinel Practice Network: purpose, methods, and policies.

The Ambulatory Sentinel Practice Network (ASPN) is a network of primary health care practices across the United States and Canada offering (1) a laboratory for the study of populations under the care of primary care providers, and (2) surveillance of primary care problems and services. This paper reports the methods and policies developed and used by ASPN to conduct studies and describes the initial sentinel practices.

Adolescent↗
PubMed1983

Alpha-fetoprotein and ultrasound scanning in the prenatal diagnosis of Turner's syndrome.

Based on data from 5 cases of fetal cystic hygroma (4 cases of Turner's Syndrome and one case of Trisomy 18) and one case of Down's Syndrome with severe subcutaneous oedema, it is concluded that amniotic fluid alpha-fetoprotein (AFP) is normal or only slightly elevated in such cases whereas AFP in fluid from the cystic structures is very high. Reported high values of 'amniotic fluid' AFP are therefore likely to have been obtained from fluids accidentally drawn from the cystic structures. Fluids from the two sources cannot be distinguished from each other visually. In support of this theory is that the maternal serum AFP was found to be normal in all cases where investigated. In the diagnosis of cystic hygromata detailed ultrasound scanning will reveal the correct diagnosis.

Adult↗