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Biomedical subjects

M M Jonas

Publications and source records attributed to M M Jonas.

At least 37 records · Page 2Linked to original sources
PubMed1997

The shape of indicator dilution curves used for cardiac output measurement in man.

1. In six patients arterial plasma lithium concentration-time curves were recorded following injection of lithium chloride into the right or left atrium. 2. Lognormal curve fitting was used to derive the areas under the first pass dilution curves. 3. Subjecting the curves produced by left atrial injection to a delay and sequential filtering produced curves that closely approximated those produced by right atrial injection. 4. We conclude that the transfer function of the right heart and lungs is equivalent to a delay and sequential filtering, that the primary indicator dilution curve is closely approximated by a lognormal curve and that loss of lithium in the lungs following right atrial injection is clinically insignificant.

Aged↗
PubMed1997

Low prevalence of antibody to hepatitis C virus in an urban adolescent population.

We tested 869 subjects attending either an urban adolescent medicine clinic or a school-based clinic for antibody to hepatitis C virus. Demographic data indicated a representative study sample, and behaviors associated with hepatitis C virus transmission. One subject (0.1%) was seropositive for antibody to hepatitis C virus, indicating a very low prevalence of hepatitis C virus exposure in adolescents.

Adolescent↗
PubMed1997

Abnormal bile acid metabolism and neonatal hemochromatosis: a subset with poor prognosis.

BACKGROUND: Inborn errors of bile acid synthesis are newly recognized disorders that may cause the phenotypic appearance of neonatal hepatitis or neonatal cholestasis. METHODS: This is a clinicopathologic study of two sets of siblings with cholestatic neonatal liver failure. RESULTS: In 3 of the infants, diagnostic evaluation, including analysis of urinary bile salts, revealed a predominance of 7 alpha-hydroxy-3-oxo-4-cholenoic and 7 alpha, 12 alpha-dihydroxy-3-oxo-4-cholenoic acids, a pattern consistent with delta 4-3-oxosteroid 5 beta-reductase deficiency, which could be primary or secondary. The fourth infant died before such testing could be carried out. In addition, all 4 infants had histologically disseminated hemochromatosis and met diagnostic criteria for neonatal hemochromatosis. In the 3 infants studied, histologic examination of the liver disclosed giant cell hepatitis with extensive loss of hepatic parenchyma and rapid progression to cirrhosis. Early treatment with ursodeoxycholic acid and cholic acid, previously reported as effective therapy, was given to 2 siblings; it failed to reverse or halt the liver damage, and both infants died. One infant, with the original diagnosis of neonatal hemochromatosis, was treated with a variety of antioxidants and chelation therapy, as recently reported. No improvement was demonstrated, and he went on to liver transplantation. CONCLUSIONS: The presentation of delta 4-3-oxosteroid 5 beta-reductase deficiency as neonatal hemochromatosis may represent a distinct subset of this disorder with an accelerated course, no response to therapy and poor prognosis.

Adult↗
PubMed1996

Hepatitis C virus infection associated with administration of intravenous immune globulin. A cohort study.

OBJECTIVE: To determine the risk of and risk factors for hepatitis C virus (HCV) infection among persons with immune deficiencies who had received intravenous immune globulin (IGIV) between March 1993 and February 1994. DESIGN: Retrospective cohort study. SETTING: An immunology program in a tertiary care hospital. PATIENTS: Of 341 persons who had received IGIV between March 1, 1993, and February 22, 1994, 278 (82%) were enrolled. The mean age for the enrolled persons was 9 years, and 99% had primary immune deficiencies. MAIN OUTCOME MEASURES: Evidence of HCV infection by detection in sera of antibody to HCV and/or HCV RNA by reverse transcriptase polymerase chain reaction. RESULTS: Twenty-three (11%) of 210 persons who received the IGIV Gammagard (Baxter Healthcare Corporation, Deerfield, Ill) became infected compared with none of 52 persons who received exclusively other IGIV products (P=.01). In a multivariate analysis, HCV infection was associated only with Gammagard produced from plasma screened by second-generation (multiantigen) anti-HCV tests (P=.03). Hepatitis C virus RNA was detected in Gammagard, and the risk of transmission to recipients increased with increasing quantity of HCV RNA infused, from 0 for those who received no HCV RNA-positive lots to 29% for the quartile of patients receiving the greatest amount (P<.001). At least 9 different lots of Gammagard were required to account for all cases. CONCLUSION: Gammagard was the only IGIV product implicated in the transmission of HCV. Infection was associated with higher quantities of HCV RNA in Gammagard produced from second-generation anti-HCV-screened plasma. Further studies are needed to determine reasons for the infectivity of Gammagard, and viral inactivation and removal steps are needed to ensure the safety of IGIV products.

Alanine Transaminase↗
PubMed1996

Hepatitis C infection in children who received extracorporeal membrane oxygenation.

OBJECTIVE: To determine the prevalence of antibody to hepatitis C virus (HCV) in a cohort of neonates who received extracorporeal membrane oxygenation (ECMO) therapy, and to determine risk factors associated with seropositivity. DESIGN: Eighty-three patients who had been treated with ECMO as neonates (from August 1986 through January 1992) at Children's Hospital, Boston, were tested for antibodies to HCV. The medical records were reviewed, and information regarding neonatal history was obtained. Anti-HCV seronegative and seropositive children were compared using univariate and multivariate analyses. RESULTS: Seven patients (8%) were anti-HCV seropositive of the seven seropositive children, four (57%) currently have ALT values of more than 1.5 times the upper limit of normal; only five of the 52 (9.6%) seronegative patients have values this high (P < .001). Patients in the seropositive group had received blood screened by "surrogate markers" (6 of 50) or by ELISA-1 anti-HCV testing (1 of 33). Significant differences between the seropositive and seronegative patients were found with respect to the aminotransferase and bilirubin levels during the initial ECMO hospitalization. The last ALT value before discharge was the only significant predictor of HCV infection in the multivariate model. CONCLUSION: Neonates treated with ECMO are at risk for the development of HCV infection. Neonates who received blood products from donors screened by surrogate markers or ELISA-1 anti-HCV testing should be considered at risk. Neonates who had an abnormal ALT value at the time of discharge are most likely to be anti-HCV seropositive.

Biopsy↗
PubMed1996

Update on viral hepatitis in children.

Recent discovery of the two major agents responsible for non-A, non-B hepatitis has led to rapid progress in the diagnosis and prevention of viral hepatitis. Newly implemented vaccine strategies against hepatitis A and hepatitis B are protecting children from infection, and new immunomodulatory therapy with interferon-alpha is being used to eradicate disease in patients chronically infected with hepatitis virus B or C.

Adolescent↗
PubMed1996

Hepatitis C virus infection: clinical aspects and treatment with interferon alfa.

Screening for antibodies to hepatitis C virus (HCV) has substantially reduced the risk of HCV infection from transfusion of blood and blood products. Nevertheless, new infections may continue to occur. These infections may be caused by donor infections that escape detection or by insufficient decontamination of blood products during preparation. Frequently, HCV infection becomes chronic, is clinically silent, and can be associated with extrahepatic illnesses and liver cancer. A recent outbreak of HCV infection in patients who received intravenous immunoglobulin has permitted study of this infection in immunocompromised hosts. Some evidence indicates that this infection is more virulent in these patients, and our experience at Children's Hospital, Boston, Massachusetts, substantiates this finding. In this article, epidemiology and modes of transmission of HCV, pathogenesis of HCV infections, differential diagnosis, and clinical features of HCV infection in both children and adults are discussed. Particular attention is given to the serologic findings seen in the spectrum of diseases associated with chronic HCV infection. The mechanisms of action of interferon alfa treatment of HCV infections are discussed. However, results of interferon alfa treatment of patients with HCV infection at Children's Hospital are preliminary.

Adult↗
PubMed1996

A new tracheal tube for difficult intubation.

We have compared a new Portex tracheal tube with the Oxford tube in performing simulated grade 3 difficult intubations. The Portex tube was modified so that the bevel faced backwards, as in the Oxford tube. A gum elastic introducer was used with both tubes. The time taken and number of attempts needed were recorded, with changes in arterial pressure, heart rate and incidence of sore throat. Both tubes were successful in avoiding the problem of obstruction at the cords, which occurs when a standard Magill tube is used with an introducer. Thus the new tube has the merits of the Oxford tube without the disadvantages of rubber. It is suitable for both easy and difficult intubations with advantages in safety, cost and convenience. An unexpected but important finding was a clear learning effect, despite both investigators being familiar with the technique at the outset. Over the course of the study, intubation time decreased progressively (P < 0.001). This provides new evidence of the need for trainees to practise the art of intubation when the cords are not visible. Our estimate of the learning "half-life" was 15 intubations; we conclude that 30 simulated grade 3 intubations would be a reasonable objective for trainees before handling high-risk cases.

Adult↗
PubMed1996

Interferon-alpha for viral hepatitis.

IFN-alpha has emerged as a promising treatment of chronic viral hepatitis. Although therapeutic response to IFN is far from universal, efficacy has been demonstrated; and studies combining IFN-alpha with other agents, as well as trials with new preparations of IFN-alpha, are under way. Children do not represent a large part of the identified population with chronic viral hepatitis. Yet children, by simple virtue of age, are more recently infected. In addition, longer life expectancies can be expected to be associated with greater morbidity from chronic viral hepatitis. Children seem to tolerate therapy with IFN-alpha well. Treatment of children with chronic viral hepatitis should be strongly considered, with protocols designed to ascertain specific pediatric safety and efficacy.

Antibodies↗
PubMed1996

Long-term hepatic regeneration and function in infants and children following liver resection.

BACKGROUND: Hepatic regeneration and function after resection has been evaluated in adults, but long-term quantitative assessment has not been performed in children. Semiquantitative short-term evaluations, including radioisotope scans, have suggested that hepatic regeneration occurs quickly in children, but the effect of chemotherapy on hepatic regeneration has not been evaluated. Treating hepatoblastoma in children increasingly includes chemotherapy before resection, hence evaluating regeneration is critical. STUDY DESIGN: A retrospective evaluation was done of ten children older than one year following anatomic hepatic resection for benign or malignant tumors. Three components were evaluated. First, hepatic function was evaluated by a series of tests of synthetic function. Second, the metabolic function of the liver was evaluated by measuring the hepatic conversion of lidocaine to its breakdown product, monoethylglycinexylidide (MEGX). Third, hepatic volume was assessed by magnetic resonance imaging scan. RESULTS: All children were clinically well at the time of evaluation. Results of tests of synthetic function were essentially normal in all patients. Serum ammonia levels were mildly elevated in six patients. Hepatocellular enzymes were mildly elevated in several children, and the alkaline phosphatase level was mildly elevated in three. A lidocaine infusion study demonstrated normal levels of MEGX in all of the children except one with positive hepatitis C serology. Studies demonstrated that hepatic volumes were below but near the expected levels in most children. Sequential studies in six children demonstrated progressive growth of the livers. No adverse effect on hepatic size was noted in the children who received chemotherapy. CONCLUSIONS: The cohort of children had adequate regeneration and function of the liver following hepatic resection. No adverse effect of perioperative chemotherapy could be identified.

Adolescent↗
PubMed1996

Clinical and virologic features of hepatitis C virus infection associated with intravenous immunoglobulin.

OBJECTIVE: To characterize the clinical features of hepatitis C virus (HCV) infection associated with the administration of intravenous immunoglobulin (IVIG) in patients with varied immunodeficiencies. DESIGN: Prospective collection of clinical and virologic data in patients determined to have HCV exposure associated with Gammagard. SETTING: Outpatient department of Children's Hospital, Boston. PATIENTS: Twenty-one patients with evidence of HCV infection were identified during a screening program initiated to detect infection in exposed individuals. They ranged from 5 to 53 years of age; 14 were children under age 18. RESULTS: Six patients presented with severe clinical hepatitis before detection by screening, 13 were detected by screening only, and 2 were first detected by screening and subsequently developed symptomatic hepatitis. Follow-up is available on 20 patients; 4 without viremia at identification have remained clinically well. Hepatitis and viremia have resolved in 2, 2 additional subjects have developed normal alanine aminotransferase (ALT) values with persistent viremia, and 13 have biochemical and/or virologic evidence of chronic hepatitis. Eight patients (7 children) have undergone liver biopsies; 7 have histologic findings of chronic hepatitis, 5 have mild fibrosis, and 2 have moderate fibrosis. HCV genotypes 1a and 1b were observed with equal frequency in this group. CONCLUSIONS: Some HCV infections associated with IVIG had a more severe, acute course than is ordinarily described. This may be attributable to host factors, such as immunodeficiencies, or virologic factors, such as inoculum or genotype. Although a large percentage (87.5%) of these individuals developed chronic infection, the natural history is not as yet completely defined.

Adolescent↗