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Biomedical subjects

H Cross

Publications and source records attributed to H Cross.

31 records · Page 2Linked to original sources
PubMed1994

Medical treatment of Rasmussen's syndrome (chronic encephalitis and epilepsy): effect of high-dose steroids or immunoglobulins in 19 patients.

We treated 19 patients with Rasmussen's syndrome (chronic encephalitis and epilepsy)--a rare progressive disorder of unknown etiology causing focal epilepsy, hemiparesis, and intellectual deterioration--with intravenous immunoglobulins, high-dose steroids, or both, to control seizures and improve the end point of the disease. Ten of 17 patients receiving steroids, and eight of nine patients receiving immunoglobulins, had some reduction of seizure frequency in the short term. Improvement in hemiparesis was slight. The effect of these drugs in ameliorating the end point of the disease in the long term remains unknown, and further multicenter studies with standardized protocols are warranted.

Adolescent↗
PubMed1993

Effects of 1,1-dichloroethene and of some of its metabolites on the functional viability of mouse hepatocytes.

1,1-Dichloroethene (DCE) is hepatotoxic in rodents, and the expression of its toxicity involves probably its metabolism. In this study the role of DCE metabolites in the generation of the hepatotoxic lesion was investigated. Hepatocytes from male BALB/c mice in suspension were used as the experimental model. Cells were incubated with DCE for up to 5 hr and cellular viability was assessed by measurement of the release of lactate dehydrogenase into the medium and by alterations in the reduction of the dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide. After incubation for 3 hr DCE at 0.5 mM caused maximal toxicity, whereas at 0.1 mM DCE was only marginally toxic. Cytotoxicity was exacerbated by pretreatment of mice with buthionine sulfoximine (1.6 g/kg), an inhibitor of glutathione biosynthesis, given 4 hr prior to hepatocyte isolation. Inclusion of N-acetylcysteine (10 mM) into the incubate protected cells against DCE-induced cytotoxicity. Coincubation with octylamine (0.5 mM), an inhibitor of cytochrome P450, abolished the cytotoxic potential of 0.5 mM DCE during incubation for 3 hr. DCE toxicity was increased in hepatocytes from mice which had received ethanol or acetone in their drinking water, both of which induce levels of the hepatic cytochrome P450 isozyme P450 2E1. Incubation of cells with the P450 2E1 inhibitors N,N-dimethylformamide (10 mM) or diethyldithiocarbamate (100 microM) protected liver cells against the detrimental effect of DCE. Pretreatment of animals with phenobarbital, which induces the P450 2B subfamily, or 3-methylcholanthrene, which induces P450 1A1, did not affect the degree of hepatocytotoxicity elicited DCE.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

New findings in the metabolism of N,N-dimethylformamide--consequences for evaluation of occupational risk.

Using a novel gas chromatographic method, specific mercapturic acids produced in the biotransformation of several formamide analogues have been quantified. Thus, N-acetyl-S-(N-methylcarbamoyl)cysteine, derived from an important industrial solvent N,N-dimethylformamide, was found to be a minor metabolite in rodents but an important one in humans. Because manifestations of hepatotoxicity of formamide analogues were always linked with the production of mercapturic acids, the risk from exposure to DMF in humans appears to be higher than that estimated from toxicological experiments on laboratory animals.

Air Pollutants, Occupational↗
PubMed1989

Differences between rodents and humans in the metabolic toxification of N,N-dimethylformamide.

The widely used industrial solvent N,N-dimethylformamide (DMF) causes liver damage in occupationally exposed persons and is suspected of involvement in the generation of certain occupational malignancies. Here the extent of the biotransformation of DMF to three urinary metabolites has been compared in humans and rodents. The metabolites, which were quantified by gas chromatography (GC) are N-(hydroxymethyl)-N-methylformamide (HMMF), which yielded N-methylformamide on GC analysis, a species which decomposed to formamide on GC analysis, and N-acetyl-S-(N-methylcarbamoyl) cysteine (AMCC), measured after derivatization with ethanol to give ethyl N-methylcarbamate. Ten volunteers who absorbed between 28 and 60 mumol/kg DMF during an 8-hr exposure to DMF in the air at 60 mg/m3 excreted in the urine within 72 hr between 16.1 and 48.7% of the dose as HMMF, between 8.3 and 23.9% as formamide, and between 9.7 and 22.8% as AMCC. AMCC, together with HMMF, was also detected in the urine of workers after occupational exposure to DMF. The portion of the dose (0.1, 0.7, or 7.0 mmol/kg given ip) which was metabolized in mice, rats, or hamsters to HMMF varied between 8.4 and 47.3% of the dose; between 7.9 and 37.5% were excreted as formamide and only between 1.1 and 5.2%, as AMCC. The results suggest that there is a quantitative difference between the metabolic pathway of DMF to AMCC in humans and rodents. It is argued that the hepatotoxic potential of DMF may be linked to the extent of its metabolic conversion to AMCC.

Adult↗
PubMed1984

Systemic histiocytosis: an unusual cause of perianal disease in a child.

A male child first presented with chronic perianal skin disease at 33 months of age and later developed gingival disease and loose teeth associated with alveolar bone erosion. Biopsy of gingival and perianal lesions showed histiocytic proliferation. Following therapy with vinblastine, prednisone, methotrexate, and cyclophosphamide, the lesions healed but disease recurred in the mastoid and was successfully treated with vinblastine alone. Although the perianal area is an unusual site of skin involvement in systemic histiocytosis, this disorder should be considered in any child with chronic unexplained perianal disease, and biopsy of these lesions should be obtained.

Alveolar Process↗
PubMed1983

The relationship between level of adjustment and expectations for therapy.

Investigated Goldstein's (1962) hypothesis of a curvilinear relationship between client expectancy and psychotherapy outcome, based partly on a similar relationship between client expectancy and adjustment. One hundred and ten new clients at a university counseling center completed self-assessments and were rated on an adjustment scale by their therapists at the beginning and end of therapy. There was no curvilinear relationship between adjustment and expectancy, but a linear relationship between expectancy and self-assessed outcome was found. Because no relationship was obtained between expectancy and therapist-defined outcome, method variance may account for the association between expectancy and outcome from the client's perspective.

Consumer Behavior↗
PubMed1981

In utero Epstein-Barr virus (infectious mononucleosis) infection.

A male infant infected in utero with Epstein-Barr virus (EBV) demonstrated a syndrome of multiple congenital anomalies (micrognathia, cryptorchidism, central cataracts), hypotonia, thrombocytopenia, persistent monocytosis, proteinuria, and multiple areas of metaphysitis at birth. Lymphocytes were Epstein-Barr nuclear antigen (EBNA) positive (18%) and persisted in culture for three months. He had antibody to early antigen (anti-EA), IgM-viral capsid (anti-VCA), and EBNA (anti-EBNA) detectable at 22 days of age. All attempts to isolate infectious agents or to serologically identify other infectious causes for his syndrome were negative.

Abnormalities, Multiple↗
PubMedDate not supplied

N-alkylformamides are metabolized to N-alkylcarbamoylating species by hepatic microsomes from rodents and humans.

Hepatotoxic formamides such as N-methylformamide (NMF) and N,N-dimethylformamide (DMF) are metabolized in vivo to N-acetyl-S-(N-methylcarbamoyl)cysteine via oxidation at the formyl carbon, which yields a reactive intermediate. The hypothesis was tested that this biotransformation route can be studied in vitro with hepatic fractions. NMF was incubated with microsomes or cytosol obtained from BALB/c mice, and metabolically generated N-methyl-carbamoylating species were analyzed after derivatization with ethanol in base to furnish ethyl N-methylcarbamate. Generation of metabolite was catalyzed by microsomes, but not by cytosol. Detection of the N-methylcarbamoylating species was dependent on the presence in the incubation mixture of NMF, viable microsomes, NADPH, and a thiol-containing agent such as glutathione. Metabolite formation was inhibited by SKF 525-A (3 mM) and abolished when the incubation atmosphere consisted of an air/carbon monoxide mixture (1:1) instead of air. Metabolism was not induced by pretreatment of mice with phenobarbital or beta-naphthoflavone. N-Ethylformamide and the DMF metabolite N-(hydroxymethyl)-N-methylformamide, but not DMF, were metabolized by microsomes to the N-alkylcarbamoylating metabolite at a measurable rate. NMF metabolism was also observed with liver microsomes from Sprague-Dawley rats or from humans. In the case of rat microsomes the rate of metabolism was half of that measured with murine microsomes. The results suggest that (i) the metabolic toxification of NMF can be studied in hepatic microsomes and (ii) the oxidation of the formyl moiety in N-alkylformamides is catalyzed by cytochrome P-450.

Animals↗
PubMedDate not supplied

The relationship between child temperament and early childhood caries.

PURPOSE: Among the potential risk factors associated with nursing caries/baby bottle tooth decay--a subset of Early Childhood Caries (ECC)--is a "strong-tempered" behavioral style in the child. However, the few empirical studies that have investigated this description remain controversial. The research goal of this study was to operationalize the "strong-tempered" profile and investigate its association to parental feeding practices and ECC levels. METHODS: In an observational-correlational study design, 58 children (ASA I), ages 18 to 70 months (M = 43 months, SD = 17), were reliably assessed for ECC levels by a clinical evaluator. A second evaluator, blind to ECC status, interviewed parents using a demographic survey, a feeding practices measure, and the EAS Temperament Survey for Children. RESULTS: Multiple regression analyses indicated that none of the four temperament factors (Emotionality, Activity, Sociability, and Shyness) significantly predicted duration of feeding habit defined as the length of time in months that the child breast or bottle fed, whichever lasted the longest. However, the combination of greater duration of feeding habit and higher levels of Shyness predicted all three measures of ECC: the presence or absence of caries (r2 = .19, P < .001), the number of carious teeth (r2 = .23, P < .001) and the number of carious surfaces (r2 = .21, P < .001). Furthermore, the addition of Native status significantly increased the predictive value of all of three models (r2 = .37, r2 = .43, r2 = .29, respectively, Ps < .0001). CONCLUSION: Temperament did not predict the duration of feeding habit but together, shyness and duration of feeding habit was associated with ECC.

Bottle Feeding↗
PubMedDate not supplied

Temperament and trait anxiety as predictors of child behavior prior to general anesthesia for dental surgery.

Children's individual styles of interaction with the environment (temperament) influence stable tendencies towards distress (trait anxiety) and context-specific manifestations of distress (state anxiety). Measures of temperament and trait anxiety were examined as predictors of state anxiety (i.e., disruptive behaviors) in the presurgical setting. During a 2-month period, 51 nonpremedicated, healthy children (M = 3 years of age) were consecutively studied-as they presented to a hospital setting for dental treatment under general anesthesia (GA). Using correlation and backward multiple regression analyses, one temperament category (shyness), but not trait anxiety (the revised CMAS), predicted disruptive behaviors (the revised MBPRS) during preseparation (r2 = .16, P = .0038) and separation (r2 = .09, P = .0281) from parents. Shyness, age, and gender best predicted disruptive behaviors during preseparation (multiple R2 = .31, P = .0005). Temperament (a) predicts children's distress in the presurgical setting, and (b) appears to be moderated by age, gender, and interpersonal factors. Awareness of temperamental influences can help predict children's behavior and aid in the presurgical care of children.

Age Factors↗