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Biomedical subjects

J Hummel

Publications and source records attributed to J Hummel.

At least 37 records · Page 2Linked to original sources
PubMed1995

Management of type II odontoid process fractures in geriatric patients; a prospective study of sequential cohorts with attention to survivorship.

After institutional review defined an unacceptable mortality rate in nonoperative treatment of elderly patients with odontoid process fracture without neurological deficit, we undertook a prospective study to determine the influence of early surgical stabilization on perioperative mortality in geriatric odontoid process fracture patients without neurologic injury. Analysis suggests that acute perifracture mortality in this high-risk group can be significantly decreased and potentially eliminated by this approach.

Aged↗
PubMed1994

Effect of pacing site on the atrial electrogram at target sites for slow pathway ablation in patients with atrioventricular nodal reentrant tachycardia.

Atrial electrograms recorded from target sites during radiofrequency catheter ablation of the slow atrioventricular (AV) nodal pathway are often fractionated and may be associated with a late, high frequency component (the slow pathway potential). The purpose of the current study was to assess the effects of slow pathway ablation on the morphology of the atrial electrogram and to determine whether target site electrograms display direction dependent changes in morphology during atrial pacing maneuvers. Twenty-six patients with typical AV nodal reentry had electrograms recorded from target sites before and after successful ablation of the slow AV nodal pathway and during pacing from the high right atrium and distal coronary sinus at cycle lengths of 500 and 300 msec. There was no significant change in the duration or degree of fractionation of the atrial electrogram as the result of slow pathway ablation. In contrast, the duration and degree of fractionation were less when pacing from the coronary sinus compared with sinus rhythms or right atrial pacing. Pacing rate did not affect electrogram morphology. These data suggest that the morphology of the slow pathway target site electrogram is dependent on the direction of atrial activation and that the "slow pathway potential" does not represent activation of an anatomically discrete pathway.

Adult↗
PubMed1994

Estimating the cost of using non-physician providers in primary care teams in an HMO: where would the savings begin?

The economic effects attributable to employing non-physician providers (NPPs) in primary care in a large HMO were estimated by calculating the per member per month (PMPM) cost for primary care provider compensation as a function of panel size for an MD/NPP provider team. After establishing an adjusted baseline of 1352 patients for an MD working alone, we hypothetically hired an NPP for each MD and increased the average panel size from 1400 to 2800 patients in increments of 200 while reducing the number of teams to keep total enrollment constant. For panel increases of less than 650 patients the addition of an NPP to a team represented a net economic loss in terms of professional service costs. By expanding the panel size for an MD/NPP team by more than 650 patients we were able to predict a linear increase in savings. The model projects that panels of 2400 patients would result in savings of $1.38 per member per month, approximately $1.65 million dollars per 100,000 enrollees per year.

Cost Savings↗
PubMed1991

A new profilometric method for determination of enamel and dentinal abrasion in vivo using computer comparisons: a pilot study.

A technique, sensitive enough to determine both dentinal and enamel abrasion in vivo, is presented. Computer-aided profilometry was used to measure the surface of dentinal and enamel samples before the experiment. Samples were subsequently placed in the buccal flanges of the mandibular dentures of two test subjects, who then brushed these pieces with a soft, multitufted brush, and two different toothpastes. Results of these pilot studies showed that the samples brushed with Colgate BiFluor had markedly less enamel and dentinal abrasion than did those brushed with Smokers. In addition, surface roughness was greater in the specimens brushed with Smokers. However, person-to-person variation can have a great influence on the abrasion process; moreover, only two persons were involved in this pilot study, and no definitive statement can be made about the effect of the toothpastes.

Dental Enamel↗
PubMed1982

Effect of ethanol on dimethylnitrosamine activation and DNA synthesis in rat liver.

Male Wistar rats were treated for 2 weeks with 20% ethanol in the drinking water. Twenty four hours after the termination of treatment animals were injected with different doses of [14C]dimethylnitrosamine and killed 4 h thereafter. The amounts of 7-methylguanine and O6-methylguanine present in liver DNA were determined. There was no significant difference in the levels of either DNA alkylation product between untreated controls and animals pre-treated with ethanol. The O6-methylguanine/7-methylguanine ratio was also unchanged. Specific radioactivity levels in the cellular protein of [14C]dimethylnitrosamine injected animals were slightly lowered after ethanol pre-treatment. In contrast, incorporation of labelled guanine into liver DNA was greatly enhanced at all DMN doses in ethanol pre-treated animals indicating an increase in DNA synthesis. This enhancement of DNA synthesis was confirmed at different ethanol doses, given either in the drinking water or by stomach tube, by the increase in specific radioactivity of liver DNA and the increase in the number of labelled nuclei following [3H]thymidine pulse-labelling.

Animals↗
PubMed1980

Induction of DNA strand breaks by nitrosocimetidine.

The DNA of a transformed epithelial mouse cell line was studied by means of the alkaline filter elution test. Addition of N-nitrosocimetidine (NC) to the cells in vitro resulted in a concentration-dependent increase in DNA damage. In contrast cimetidine itself had no effect. The capacity of NC to generate DNA strand breaks was found to be smaller by comparison with the potent gastric carcinogen N-methyl-N'-nitro-N-nitrosoguanidine (MNNG).

Animals↗
PubMed1979

DNA damage induced in vivo evaluated with a non-radioactive alkaline elution technique.

A modification of the alkaline filter elution test was used to study damage to liver DNA of NMRI mice following in vivo treatment with various hepatocarcinogens and drugs causing liver enlargement. Liver cell nuclei were prepared and lysed on top of polyvinyl filters. DNA was eluted, and the amounts both remaining on the filter and in the eluate were measured colorimetrically. Dimethylnitrosamine (DMN), diethylnitrosamine (DEN), N-nitrosomorpholine and methyl methanesulfonate (MMS) caused significant enhancement of DNA passage through the filters, whereas N-acetylaminofluorene (AAF), 4-dimethylaminoazobenzene (DAB), phenobarbital, halothane and CCl4 did not. The applicability of this short term test is discussed.

Animals↗