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Biomedical subjects

R B Rubin

Publications and source records attributed to R B Rubin.

16 recordsLinked to original sources
PubMed1999

Hepatic iron concentration: noninvasive estimation by means of MR imaging techniques.

PURPOSE: To identify a magnetic resonance (MR) imaging method sufficiently sensitive and specific in the estimation of hepatic iron content to obviate liver biopsy. MATERIALS AND METHODS: Thirty-eight patients underwent percutaneous needle biopsy of the liver with chemical measurement of the hepatic iron concentration and hepatic MR imaging with several spin-echo and gradient-recalled-echo (GRE) techniques. Correlations between MR imaging parameters and the hepatic iron concentration were determined. RESULTS: Inverse curvilinear relationships were noted between several MR parameters and hepatic iron concentrations. GRE sequences with short repetition and echo times were more accurate and precise than spin-echo sequences for the estimation of hepatic iron concentration. A GRE sequence with a repetition time of 18 msec, an echo time of 5 msec, and a flip angle of 10 degrees showed close correlation between the hepatic iron concentration and the natural logarithm of the ratio of the signal intensity of liver to the SD of background noise (r = -0.94) and low coefficient of variation (12%). CONCLUSION: MR imaging with these parameters is a rapid, noninvasive, and accurate modality for estimation of hepatic iron concentration; it is sufficiently accurate and precise to obviate liver biopsy for the purpose of measuring hepatic iron concentration.

Adult↗
PubMed1996

Iron in liver diseases other than hemochromatosis.

There is growing evidence that normal or only mildly increased amounts of iron in the liver can be damaging, particularly when they are combined with other hepatotoxic factors such as alcohol, porphyrogenic drugs, or chronic viral hepatitis. Iron enhances the pathogenicity of microorganisms, adversely affects the function of macrophages and lymphocytes, and enhances fibrogenic pathways, all of which may increase hepatic injury due to iron itself or to iron and other factors. Iron may also be a co-carcinogen or promoter of hepatocellular carcinoma, even in patients without HC or cirrhosis. Based on this and other evidence, we hope that the era of indiscriminate iron supplementation will come to an end. Bloodletting, a therapy much in vogue 2 centuries ago, is deservedly enjoying a renaissance, based on our current understanding of the toxic effects of iron and the benefits of its depletion.

Carcinoma, Hepatocellular↗
PubMed1994

Accuracy of frozen-section (intraoperative consultation) diagnosis of ovarian tumors.

OBJECTIVE: Frozen-section evaluation of ovarian tumors can be used to establish a histopathologic diagnosis and guide the surgeon to perform the appropriate surgical procedure. A retrospective study was conducted to determine the accuracy of frozen-section diagnosis of ovarian tumors. STUDY DESIGN: Frozen- and permanent-section diagnoses were divided into three categories (benign, borderline, and malignant). The sensitivity, specificity and predictive values, and 95% percent confidence intervals of each frozen-section diagnosis were determined. RESULTS: Three hundred eighty-three ovarian tumors that underwent frozen-section evaluation between June 1983 and June 1993 were studied. The final histopathologic diagnosis was 61.1% benign, 7.6% borderline, and 31.3% malignant. Frozen section was accurate in 92.7% of all cases and inaccurate in 7.3%. The sensitivity for malignant tumors was 92.5% tumors (95% confidence intervals 87.7% to 97.2%), the sensitivity for borderline tumors was 44.8% (95% confidence interval 26.4% to 63.2%). The specificity for benign tumors was 92.0% (95% confidence interval 88.6% to 95.4%) but increased to 97.9% (95% confidence interval 96.1% to 99.7%) if borderline tumors were excluded. The positive predictive value and 95% confidence intervals were 92.0% (88.6% to 95.4%) for benign tumors, 65% (43.6% to 86.5%) for borderline tumors, and 99.1% (97.3% to 100.0%) for malignant tumors. Thirteen of 16 (81%) ovarian lymphomas and tumors metastatic to the ovary were correctly identified by intraoperative frozen section. The sensitivity for borderline serous tumors was 64.3% and for borderline mucinous tumors 30.8% (p = 0.48). CONCLUSION: With the exception of borderline tumors, the sensitivity and specificity of frozen-section diagnosis of ovarian tumors are high. Borderline tumors remain difficult to accurately diagnose at frozen section because of the extensive sampling required. Frozen-section diagnoses have important implications regarding the type and extent of surgery performed at the initial operation.

Adolescent↗
PubMed1992

Medical complications of cocaine: changes in pattern of use and spectrum of complications.

We sought to determine whether changes in patterns of cocaine use, characterized by widespread abuse of cocaine alkaloid, have altered the nature and severity of medical complications over the past decade. Infectious complications, almost invariably associated with intravenous use, accounted for nearly all hospital admissions in the early 1980s. Cardiovascular, neurologic and psychiatric complications rose dramatically after 1987 both in absolute number and as a proportion of total complications. This rise parallelled increases in the absolute number and proportion of hospitalized patients smoking cocaine alkaloid or using intranasal cocaine, both disproportionately associated with non-infectious complications. While infectious complications were often local in nature, serious neurologic and cardiovascular sequelae were observed. These data indicate that changes in patterns of cocaine use have altered the nature and increased the severity of medical complications with a shift from infectious to cardiovascular, neurologic and psychiatric complications which may be life-threatening and associated with substantial morbidity.

Administration, Intranasal↗
PubMed1990

Rhabdomyolysis and acute renal failure associated with cocaine abuse.

Cocaine abuse has emerged as a major public health problem among young adults. Illicit use of cocaine has been associated with an increasing array of medical complications. Both traumatic and nontraumatic rhabdomyolysis, often complicated by acute renal failure, has recently been described following cocaine abuse. The present report describes our experience with 15 such patients and serves to further define the spectrum of muscle injury associated with cocaine abuse ranging from the incidental finding of elevated serum levels of muscle enzymes to acute renal failure. Those patients who developed renal failure experienced more severe rhabdomyolysis in association with trauma, seizures or hyperpyrexia.

Acid-Base Equilibrium↗
PubMed1989

Cocaine-induced rhabdomyolysis masquerading as myocardial ischemia.

PURPOSE: Cocaine abuse has recently emerged as a major problem among young adults, and is increasingly associated with a variety of medical complications. In view of recent reports demonstrating that illicit cocaine use may cause rhabdomyolysis, we reviewed the collective experience of a university-affiliated medical center to identify patients with cocaine-induced rhabdomyolysis. PATIENTS AND METHODS: Among hospital admissions due to acute cocaine abuse during the period June 1987 through June 1988, we identified seven patients who exhibited biochemical evidence of skeletal muscle injury. Six of these patients presented within one hour of free-basing cocaine with complaints of thoracic skeletal muscle pain. Hospital admission was prompted by the suspicion of myocardial ischemia or infarction. The remaining patient was incidentally found to have an elevated serum level of creatine phosphokinase (CPK) after abusing cocaine and was hospitalized to exclude a cardiac origin. RESULTS: Serum CPK levels in the seven patients rose to a mean peak value of 16.1 +/- 3.6 mu kat/L, and returned toward normal within 72 hours. A cardiac origin for the elevated CPK values was excluded by negative results of determinations of CPK-MB fractions. CONCLUSION: Rhabdomyolysis must be added to the every-growing list of medical complications associated with the illicit use of cocaine. Skeletal muscle injury may be a more common complication of cocaine abuse than has previously been appreciated, escaping medical attention when the clinical manifestations are relatively mild. The importance of recognizing this clinical entity lies in the potential confusion with myocardial ischemia. This point is illustrated by the fact that each of our patients was hospitalized to exclude the possibility of cocaine-induced myocardial infarction. Cardiac ischemia could not be differentiated from skeletal muscle injury solely on the basis of clinical assessment.

Adult↗
PubMed1986

Contextual age as a life-position index.

A contextual age construct was developed and examined as a transactional, life-position index of aging. The eighteen-item contextual age index included six interrelated dimensions: physical health, interpersonal interaction, mobility, life satisfaction, social activity, and economic security. In addition to the development of the index, associations among contextual age and sociodemographic characteristics were examined for a sample of 640 persons. Chronological age was correlated negatively with mobility and physical health, and positively with economic security, life satisfaction, and interpersonal interaction. Mobility, economic security, life satisfaction, physical health, and interpersonal interaction discriminated between chronological age groups. Interpersonal interaction, economic security, physical health, and social activity were predictors of life satisfaction. The contextual age construct raises questions concerning several negative myths about aging. The findings reflect the weak validity of chronological age as a unidimensional indicator of life-position and well-being.

Adult↗
PubMed1984

A preliminary investigation of the information carrying potential of voluntary eye movements.

This paper reports the preliminary findings of a study on the information carrying potential of voluntary eye movements. An ocular communication device, originally developed at the Denver Research Institute, was used to determine how fast information can be transmitted by voluntary eye movements. The tentative findings are that: a maximum information throughput of roughly 10 bits/s is possible and the DRI device merits further development. The primary relevance of this study is to the development of communication aids for the severely handicapped.

Communication Devices for People with Disabilities↗
PubMedDate not supplied

Changes in communication apprehension, satisfaction, and competence in foreign dialect and stuttering clients.

This study examined changes in predispositions toward communication over the course of therapy. Results indicated that both foreign dialect and stuttering clients had significantly lower levels of communication apprehension and higher levels of communication competence after 3 1/2 months of their respective therapies; each client group also demonstrated significant improvements in the speech parameters upon which treatment focused. Discussion focused on the utility of using communication measures with clinical populations.

Adult↗
PubMedDate not supplied

Iron and chronic viral hepatitis: emerging evidence for an important interaction.

Iron is an essential element for cell survival; it serves as a cofactor for essential enzymes in oxidative metabolism and (in the form of heme) as the major oxygen transporter in most forms of life on earth. Both deficiency and excess of iron often lead to disease. Iron is necessary for the proliferation of microorganisms and neoplastic cells. The presence of iron overload facilitates infection, as evidenced by the increased risk of persons with hemochromatosis to certain infections and by the fact that patients with lesser amounts of hepatic iron appear to respond better to interferon therapy for chronic viral hepatitis than those with larger amounts of hepatic iron. Viral hepatitis is a common cause of morbidity and mortality. Recent studies suggest that there is a key link between iron metabolism and the pathophysiology of viral hepatitis. The lobular and cellular distribution of iron in the liver may be as important as the total quantity of iron present. Whether iron removal will prove useful in the long-term management of chronic viral hepatitis is an issue in need of further well-designed, randomized, controlled trials.

Chronic Disease↗
PubMedDate not supplied

A rapid protein profiling system that speeds study of cancer and other diseases.

To realize its potential to transform research and medicine, genomics must be complemented by protein expression data. Analysis by SELDI-TOF-MS technology, implemented in the ProteinChip System, overcomes the limitations of traditional protein analysis methods by enabling rapid analysis of small amounts of crude protein extracts and providing size and functional characterization on total cellular or tissue populations of proteins. The system has already been put to constructive use in many laboratories and has enabled researchers to determine unique protein profile signatures characteristic of progression from healthy to diseased states and back. In addition to its research applications, recent experimental successes suggest that the technology may soon find use in the important work of early diagnosis and treatment of infectious diseases, cancer, and other medical conditions.

Antibodies↗