How to write and take objective, multiple choice examinations. Quantitative analysis of the scientific data base.

Although there are numerous ways in which physicians evaluate one another and themselves, the multiple choice examination has become the key method for evaluating the scientific data base of both medical students and postgraduate physicians. Knowledge of the mechanisms at work in such examinations is thus important for both giving and taking these examinations. Analysis of these mechanisms is now provided.

Effects of long-term hydration leading to the development of polar channels in hairless mouse stratum corneum.

Dramatic increases in in vitro permeability coefficients have been observed following the long-term hydration (days) of hairless mouse skin. The effect is greatest for extremely polar or ionized solutes. Differential scanning calorimetry has been utilize in complementary studies in an attempt to assess if the altered permeability may be due to the irreversible alteration of lipid fluidity or keratin structure.

The role of combustion products in building-associated illness.

The role of combustion products in building-associated illness is addressed. The authors emphasize carbon monoxide, nitrogen dioxide, wood smoke, and vehicle exhaust. The limited literature available suggests that combustion products, other than tobacco smoke, may be a relatively uncommon cause of building-related problems.

Dose-dependent enhancement effects of azone on skin permeability.

In vitro permeability experiments have been combined with differential scanning calorimetry (DSC) studies in an attempt to address the dose-dependent influence of Azone on the permeability coefficients of solutes for hairless mouse stratum corneum. A spray technique was developed to deliver uniformly and quantitatively small amounts of Azone to the stratum corneum. Permeability data obtained for several model solutes of varying lipophilicity suggest lipid fluidization and polar route enhancement as the mechanisms of action for Azone.

Innovation within the federal healthcare services: initiatives and promises.

Within the healthcare services industry, innovation is offered as a process for ameliorating issues, improving services, and getting the most out of scarce resources. Medical Services in the Army, Navy, Air Force, Veterans Administration, and the Public Health Service have formed a Federal Healthcare Innovation Network (FHIN) to optimize the use of this management tool. In this article, the concept of innovation in healthcare services management and delivery is reviewed, initiatives in innovation within the five federal healthcare services are discussed, and the promises innovation holds for improved healthcare delivery are addressed.

Treatment of multiple apocrine hidrocystomas with the carbon dioxide (CO2) laser.

The apocrine hidrocystoma tends to occur as a solitary facial cystic lesion. We report an unusual patient in whom there were multiple apocrine hidrocystomas scattered over the periorbital region and ears. Although solitary apocrine hidrocystomas are easily treated with excision, we had good results employing carbon dioxide laser vaporization in the treatment of numerous hidrocystomas.

Xeroderma pigmentosum.

Xeroderma pigmentosum is a rare, recessively inherited, sun-sensitive disorder with a defective DNA repair mechanism that is the best model currently available linking human cancer to exposure to a specific carcinogen. Laboratory and epidemiological studies of this disease are providing extensive insight into the etiology of cancer in the general population.

Prognostic value of morphometry in papillary thyroid carcinoma.

The value of morphometric analysis in addition to standard prognostic indicators was studied in 28 cases of papillary thyroid carcinoma. Standard features included age, sex, lymph node status, tumor size, and encapsulation. The mean follow-up was 47 months (maximum, 140 months).

Enhancement of assays of activities of endonucleases on defined substrates by Poisson and non-Poisson combinatoric analysis.

Assay of endonuclease activity, as performed in most laboratories, depends upon change in form of small, defined substrate molecules, with a secondary computation required to obtain a determination of enzyme activity. We now explore the assumptions inherent in these computations and provide a series of equations that permit more accurate determinations of enzyme activity from assays of this type. These equations allow information to be obtained not only from substrate fractions left uncleaved by the endonuclease, upon which conventional systems rely, but also from products cleaved by the enzyme.

Simultaneous determination of pentoxifylline and three metabolites in biological fluids by liquid chromatography.

We describe a sensitive and specific liquid-chromatographic assay for pentoxifylline and three of its metabolites in human plasma and urine. Addition of hydrochloric acid to the sample before extraction, and incorporation of acetic acid in the chromatographic eluent, allow the simultaneous determination of the four compounds plus an internal standard in one chromatographic run. Unlike gas-chromatographic procedures, this method does not involve derivatization no similar analysis of serum or plasma samples has been described before now.

The Muir-Torre syndrome: a disease of sebaceous and colonic neoplasms.

The Muir-Torre syndrome of sebaceous neoplasms of the skin, with or without keratoacanthomas, and multiple low-grade visceral malignancies with prolonged survival is a rare disorder. Colonic polyps are frequently present, and the syndrome appears to be familial. We report 2 unrelated patients with the Muir-Torre syndrome.

Plasma concentrations of vitamin K1 and PIVKA-II in bottle-fed and breast-fed infants with and without vitamin K prophylaxis at birth.

Plasma vitamin K1 and proteins induced by vitamin K absence (PIVKA) were assayed simultaneously 1-4 days and 29-35 days after delivery in three groups of infants: breast-fed not receiving vitamin K at birth (n = 12), bottle-fed without vitamin K administration at birth (n = 7) and breast-fed receiving 1 mg vitamin K1 administered by intramuscular injection at birth (n = 13). The bottle-fed infants had a significantly higher vitamin K1 plasma level than breast-fed infants who did not receive vitamin K1 at birth. Extremely high levels of vitamin K were obtained 1-4 days after intramuscular administration.

Adenocarcinoma at the ileo-cutaneous junction following subtotal colectomy for ulcerative colitis. Case report.

Adenocarcinoma of the ileo-cutaneous junction is exceedingly rare. We report a case. The clinical presentation and pathogenesis are discussed.

Multiple connective tissue nevi.

Connective tissue nevi are uncommon, and rarely suspected clinically because of their diverse morphologic presentations. Histologically, we define connective tissue nevi as discrete areas within the papillary or recticular dermis where a clear predominance or depletion of collagen, elastin, or glycosaminoglycans may be found. We report a case of multiple connective tissue nevi with a predominance of dermal collagen deposition, without extracutaneous findings and no family history of connective tissue nevi.

Chromatography of fat-soluble vitamins in clinical chemistry.

A review is presented of current gas and liquid chromatographic methods for the determination of the fat-soluble vitamins A, D, E and K and the provitamin A beta-carotene in biological samples of human origin. For each vitamin, the discussion successively focuses on procedures for sample preparation, gas and liquid chromatographic systems and principles of detection. The emphasis is on liquid chromatography, which is gradually becoming a standard technique in fat-soluble vitamin assays.

Beyond hybridomas. Cell identification by in situ nucleic acid hybridization.

Nucleic acid hybridization is a powerful technique that has been developed almost entirely by molecular biologists. It has the potential to identify specific types of cells with far greater sensitivity and specificity than such current methods as polyclonal or monoclonal antibodies or lectins. As the RNAs or DNAs (probes) needed for this technique become available, it is likely to replace other methods of identifying many kinds of cells in tissue sections.