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Biomedical subjects

M Schwartz

Publications and source records attributed to M Schwartz.

At least 955 records · Page 53Linked to original sources
PubMedDate not supplied

Transesophageal echocardiography in the diagnosis of the persistent left superior vena cava.

Three patients with suspected persistent left superior vena cava (PLSVC) diagnosed by transthoracic echocardiography underwent single-plane transesophageal echocardiography. In all three patients transverse cuts through right atrium and coronary sinus demonstrated the presence of PLSVC. Agitated contrast injection into the left antecubital vein opacified PLSVC and coronary sinus in all cases. Transesophageal echocardiography is superior to transthoracic echo in the diagnosis of PLSVC and associated cardiac anomalies.

Adult↗
PubMedDate not supplied

Comparative performance of gated perfusion SPECT wall thickening, delayed thallium uptake, and F-18 fluorodeoxyglucose SPECT in detecting myocardial viability.

To evaluate the comparative abilities of gated single photon emission computed tomography (SPECT) wall thickening, delayed thallium-201 (Tl-201) SPECT, and F-18 fluorodeoxyglucose (FDG) SPECT in detecting myocardial viability, 23 patients with previous myocardial infarction and clinically suspected viability were studied. Each patient had at least 1 extensive fixed perfusion defect on rest/stress technetium-99m sestamibi SPECT. A total of 41 major vascular territories had fixed defects. The mean (+/- 1 SD) left ventricular ejection fraction determined from gated perfusion SPECT was 26% +/- 11%. Wall thickening was assessed in a semiquantitative fashion by the regional increase in myocardial intensity during systole and was considered normal when a > or = 20% increase was observed. Tl-201 SPECT was acquired 4 hours after resting tracer injection was administered. Viability was considered present when regional defect Tl-201 count density, determined by quantitative analysis, was > 20% greater than that on the resting sestamibi scan. FDG SPECT was performed independently with a 10 mCi F-18 FDG dose after oral glucose loading was performed. A camera equipped with ultrahigh energy collimation was used. Quantitative criteria for viability were the same as for Tl-201. In the 23 patients viability within the fixed sestamibi defects was manifest by preserved wall thickening in 8 patients, delayed Tl-201 uptake in 10 patients, and FDG uptake in 18 patients. Nine major vascular territories with fixed defects were judged viable by wall thickening, 11 by Tl-201 SPECT, and 24 by FDG SPECT (P = .0009). We conclude that FDG SPECT demonstrates more evidence of myocardial viability than either gated sestamibi wall thickening or delayed Tl-201 SPECT.

Female↗
PubMedDate not supplied

Two methods of catecholamine depletion in kitten visual cortex yield different effects on plasticity.

As first clearly demonstrated by the experiments of Wiesel and Hubel, the developing visual cortex is exquisitely sensitive to sensory deprivation. Temporary closure of one eye of a kitten during a critical period that extends from 3 weeks to 3 months of age results in a dramatic cortical reorganization such that most neurones, originally binocularly driven, are dominated exclusively by the open eye. Recently, attention has been directed to chemical factors which may influence the degree of plasticity during the critical period. The work of Kasamatsu and pettigrew suggests that cortical catecholamines, especially noradrenaline (NA), are essential for the normal plastic response to visual deprivation. In an effort to clarify the role of NA in visual cortical plasticity, we have monocularly deprived kittens whose cortex had been depleted of catecholamines by the neurotoxin 6-hydroxydopamine (6-OHDA). We used two strategies to deplete cortical NA: the first, pioneered by Kasamatsu el al., utilized osmotic minipumps to deliver 6-OHDA to visual cortex; the second involved systemic neonatal injections of 6-OHDA, a technique which has proved effective in rodents. We found, using high-pressure liquid chromatography (HPLC), that both techniques produced a substantial reduction in the level of cortical NA. However, single unit recording in area 17 revealed that the plastic response to monocular deprivation (MD) was only diminished in the kittens depleted by minipump.

Animals↗
PubMedDate not supplied

Absence of homozygosity for predominant mutations in PMM2 in Danish patients with carbohydrate-deficient glycoprotein syndrome type 1.

Carbohydrate-deficient glycoprotein syndrome type 1 (CDG1; McKusick No. 212065) is an autosomal recessively inherited disease characterised clinically by central nervous system dysfunction and biochemically by hypoglycosylation of many serum proteins. Most patients with CDG1 have deficient activity of phosphomannomutase. The locus for this enzyme has been mapped to 16p13, and a gene, PMM2, encoding phosphomannomutase has been isolated. We identified 34 mutations on 36 disease chromosomes in 18 unrelated Danish patients with CDG1. All patients have less than 15% residual activity of phosphomannomutase. Two mutations account for 88% of all mutations: F119L and R141H were each found in 16 out of 36 CDG1 alleles. These two mutations were found to be in linkage disequilibrium with two different alleles of the marker D16S3020, suggesting that there is one ancestral origin for each mutation. Two new mutations, G117R and D223E, were identified also. Surprisingly, no patient was homozygous for either of the two common mutations, suggesting that homozygosity for these mutations is either lethal or so benign that such patients are not detected.

Base Sequence↗
PubMedDate not supplied

X-linked ocular albinism: prevalence and mutations--a national study.

In a national retrospective register study 112 patients with ocular albinism (OA) were identified, including 60 male patients with proven or presumed X-linked ocular albinism (XLOA). Based on the birth year cohorts 1960-1989, an XLOA point prevalence at birth of 1 in 60,000 live-born was calculated. We identified 14 XLOA families in the Danish population, and obtained DNA from affected persons in nine families. Mutation analysis of the OA1 gene demonstrated seven presumed pathogenic mutations in the nine families with XLOA: five single nucleotide substitutions predicting a change of conserved amino acids (G35D, L39R, D78V, W133R and E233K) when compared with the mouse OA1 homologue, one deletion leading to the skipping of exon 2, and one single nucleotide substitution expected to affect the 5' splice site of intron 2 were found. Subsequent genealogical investigations in the three families harbouring the same mutation disclosed that two of the three pedigrees belonged to the same family. All mutations predict crucial changes in the protein structure. Clinical examination failed to identify any phenotype-genotype pattern except a milder phenotype devoid of iris translucency in the patient with the 5'splice site mutation of intron 2.

Adolescent↗
PubMedDate not supplied

Sacral nevus flammeus simplex: the role of imaging.

Neonates with midline lumbar, thoracic, or occipital cutaneous lesions should be suspected of having spinal dysraphism and should undergo an imaging study. The aim of the present study was to evaluate whether sacral nevus flammeus simplex (SNFS) in neonates is associated with spinal dysraphism. During a period of 6 months, we prospectively examined all neonates in our center for the presence of SNFS. Those affected were evaluated for associated anomalies by physical and neurologic examination and ultrasound imaging of the lumbosacral area. Twenty-eight of 3623 neonates (0.77%) were diagnosed as having SNFS. In 64% of the SNFS patients, nevus flammeus simplex (NFS) was noted as well. Physical and neurologic examinations were unremarkable. Ultrasound imaging of the lumbosacral area was performed in 25 patients (89%) and revealed diastematomyelia in one. The results show that SNFS may constitute the only cutaneous sign of spinal dysraphism. In conclusion, we recommend that neonates with SNFS be investigated for occult spinal dysraphism.

Female↗
PubMedDate not supplied

Genetic analysis of cystic fibrosis in Denmark. Implications for genetic counselling, carrier diagnosis and prenatal diagnosis.

Cystic fibrosis is the most common, severe, inherited disease in the Caucasian population. As a consequence, the demand for genetic counselling of patients with cystic fibrosis and their families is large. In Denmark the incidence of cystic fibrosis is 1:4700, which is quite low compared to other European countries. We have investigated 268 Danish cystic fibrosis patients with respect to DNA markers (haplotypes) and the most common mutation delta F508. The delta F508 mutation is found on 88% of all cystic fibrosis chromosomes, the highest frequency reported so far. This had had an important impact on genetic counselling, prenatal diagnosis and eventually population screening. In the Danish population 78% of all couples at risk will be informative for delta F508 and will be identifiable by simple screening methods.

Cystic Fibrosis↗
PubMedDate not supplied

Radiosurgery with unflattened 6-MV photon beams.

One of the major drawbacks to doing stereotactic radiosurgery with a linear accelerator is the long time required to deliver the target dose. Single fractions of 25 Gy delivered at the isocenter and at depth in the skull may require beam times in excess of 15 min for a typical linear accelerator with a maximum dose rate of 250 cGy/min in tissue. In an effort to decrease the treatment time for this technique, the flattening filter has been removed from an AECL Therac-6 linear accelerator and the characteristics of the resulting beam have been measured. Flatness is acceptable for the field sizes used with this technique and the dose rate is increased by a factor of 2.75.

Brain Diseases↗
PubMedDate not supplied

Schizophrenia and common sense: study of 3 single cases.

There is new interest in subjective experiences of schizophrenia. This kind of analysis emphasizes the subjective stories of patients, and the methods do not pretend to have the objectivity of science. However, the plausibility and the empathetic resonance of the single case may bring subjective confirmation to the validity of an insight and indicate new directions of research. Following this line, the authors present a study of 3 single cases of 'reflexive' residual type of schizophrenia. The methods for selecting the cases and the philosophical groundings of the concept of 'reflexive schizophrenia' are explained. The analysis of the single cases revealed that (1) schizophrenic persons' cognitive deficit is related to the constitution of common sense; (2) some schizophrenics cope with the cognitive deficit by creating a theoretical corpus of axioms stemming from common sense, namely the 'axioms of everyday life'; (3) this mechanism of coping is described as an inflexible attachment to 'axioms of everydayness', and (4) this attachment to common sense releases the patient from all personal investment of self in the process of anchoring in the living world and, on this basis, allows a relatively solid, although distant, attachment to reality. The nature of deficit in schizophrenia is also discussed by confronting the phenomenological point of view and the neuropsychological, that is the so-called 'theory of mind'.

Adaptation, Psychological↗
PubMedDate not supplied

Detection of the plasma cholinesterase K variant by PCR using an amplification-created restriction site.

Ten individuals registered at the Danish Cholinesterase Research Unit were examined at the DNA level for the presence of the K allele of plasma cholinesterase, using amplification-created restriction sites (ACRSs). A further nine members of a family registered at the unit were tested for mutations of the K and atypical variants. The frequency of the K allele was calculated from examination of normal material from 25 individuals, representing 50 random alleles. The results show that the ACRS method successfully demonstrates the presence of the K variant, whose frequency in the Danish population was found to be 0.18. We conclude that this technique is a reliable and rapid non-radioactive diagnostic assay for detecting the plasma cholinesterase K variant.

Alleles↗
PubMedDate not supplied

Cytologic diagnosis of a solitary brain metastasis from papillary carcinoma of the thyroid. A case report.

BACKGROUND: Papillary carcinoma of the thyroid metastasizes to the brain in rare instances. In published series and case reports of metastatic papillary thyroid carcinoma, diagnosis of central nervous system (CNS) metastases has been determined by histologic methods. We present a case of papillary carcinoma metastatic to brain diagnosed by cytologic methods. CASE: A 43-year-old female, initially diagnosed at age 12 with papillary carcinoma of the thyroid metastatic to regional lymph nodes and lung, presented with head aches of increasing frequency and severity. A computed tomography scan confirmed a 1-cm nodule in the right inferior frontal lobe of the brain. For clinical reasons, the patient was followed with serial imaging for five years. At age 48 there was significant progression of the CNS disease, and the patient underwent stereotactic biopsy with drainage of cyst fluid. Cytologic examination of the cyst fluid and immunocytochemical studies confirmed the typical features of papillary thyroid carcinoma, including papillary clusters of cells with finely granular chromatin, micronucleoli, nuclear grooves and an associated psammoma body. CONCLUSION: Neurocytology is a useful technique in the examination of cystic lesions of the brain and may be the sole technique for determination of diagnosis.

Biopsy, Needle↗
PubMedDate not supplied

Neuroprotection as a treatment for glaucoma: pharmacological and immunological approaches.

PURPOSE: Primary open-angle glaucoma is a chronic, progressive optic neuropathy associated with a gradual decline in visual functions, which may lead to blindness. METHODS: In most cases, the optic neuropathy is associated with increased intraocular pressure. However, it is now generally accepted, that normalization of pressure, although necessary, is often not sufficient as a remedial measure. This is because of the existence of additional risk factors, some of which emerge as a consequence of the initial damage. This situation is reminiscent of the response to a traumatic axonal insult: some of the damage is immediate and is caused by the insult itself, while some is secondary and is caused by a deficiency of growth-supportive factors as well as by toxic factors derived from the damaged tissue. Accordingly, we have suggested that glaucoma may be viewed as a neurodegenerative disease and consequently is amenable to any therapeutic intervention applicable to these diseases. CONCLUSIONS: There is evidence that neuroprotection can be achieved both pharmacologically and immunologically. Pharmacological intervention (e.g. by using selective alpha-2 adrenergic receptor agonists) neutralizes some of the effects of the nerve-derived toxic factors and possibly increases the ability of the remaining healthy neurons, at any given time, to cope with the stressful conditions. Immunological intervention boosts the body's own repair mechanisms for counteracting the toxicity of physiological compounds acting as stress signals.

Adrenergic Agonists↗
PubMedDate not supplied

Optic nerve degeneration and potential neuroprotection: implications for glaucoma.

In order to study the course of optic nerve degeneration and devise possible ways to achieve neuroprotection, a well-controlled, animal model of partial crush injury of the optic nerve was used. Following the controlled partial crush injury of the rat optic nerve, quantitative morphological and electrophysiological measurements were made of primary and secondary neuronal losses. The neuroprotective effects of NMDA-receptor antagonists and alpha 2-adrenoreceptor agonists were also studied. The results suggested that the ongoing progression of the optic nerve degeneration in glaucoma might be a consequence of the toxic extracellular environment produced by neurons that degenerate as a result of the primary cause of the disease (such as increased IOP).

Action Potentials↗
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Managed behavioral health care: a Medicaid carve-out for youth.

This DataWatch assesses the impact of a public sector-managed Medicaid mental health carve-out pilot for North Carolina youth. Access to, volume of, and costs of mental health/substance abuse services are reported. We compared a pilot managed care program, with an incentive to shift hospital use and costs to community-based services, with usual fee-for-service Medicaid. Aggregate data from Medicaid claims for youth (from birth to age seventeen) statewide are reported for five years. We found dramatic reductions in use of inpatient care, with a shift to intensive outpatient services, and less growth in mental health costs. These findings demonstrate that public sector-managed care can be viable and more efficient than a fee-for-service model.

Adolescent↗
PubMedDate not supplied

Phenytoin-folic acid interaction: a lesson to be learned.

A case of a patient who developed symptomatic phenytoin-induced folic acid deficiency is reported. Folate supplementation of 5 mg/d was followed by a decrease of serum phenytoin concentration to a subtherapeutic level with a breakthrough seizure. Estimation of phenytoin's Km-Vmax Michaelis-Menten pharmacokinetic parameters in this patient demonstrated that folate supplements indeed caused a significant decrease in the Km value. This decrease correlates with a greater affinity of the metabolizing hepatic enzymes for the drug, and hence, with the resultant increase in phenytoin's metabolism and decrease of its serum concentration and anticonvulsive effect. In an era of increasing knowledge of folate's pivotal role in various diseases, we call attention to this drug-vitamin interaction, and to the previously suggested recommendation that folate supplementation should be initiated whenever phenytoin therapy commences. Because folic acid dosages as low as 1 mg/d may perturbate phenytoin's metabolism, smaller deficiency preventive doses may be the advisable allowance for phenytointreated patients with normal pretreatment folate levels. This suggestion must be confirmed by a prospective study in a large cohort of patients.

Drug Interactions↗