Conversion of DDT to DDD by pathogenic and saprophytic bacteria associated with plants.

Of 27 microorganisms examined, 23 plant pathogenic and saprophytic bacterial species were found to convert p,p' DDT to p,p' DDD under anaerobic conditions. The range of conversion of DDT (10 micrograms per milliliter) during an incubation of 14 days was from a trace to over 5 micrograms per milliliter, with the majority of the bacteria showing the greatest activity during the final 7-day period. There is evidence that metabolites of DDT other than DDD are also produced.

Mechanical vibration and conventional chest physiotherapy in outpatients with stable chronic obstructive lung disease.

To assess the effect of conventional chest physiotherapy and mechanical chest vibration on arterial blood gas levels, spirometry, and sputum production, we studied 20 stable outpatients with chronic obstructive lung disease. All patients had severe obstructive ventilatory defects with a mean FEV1/FVC ratio of 30 percent and all produced moderate amounts of sputum. Patients were randomized and received chest physiotherapy or mechanical vibration for 20 minutes. Arterial blood gas levels and spirometry obtained 20 minutes and 40 minutes after completion of the treatment did not show any significant change compared to the baseline. We conclude that neither chest physiotherapy nor chest mechanical vibration improved gas exchange, flow rates, or clearance of secretions in stable outpatients with severe chronic obstructive lung disease.

Cost-benefit comparison of aerosol bronchodilator delivery methods in hospitalized patients.

We compared two modes of aerosol bronchodilator delivery in 34 patients hospitalized with obstructive airways diseases. The standard mode, therapist-administered up-draft nebulization (UDN), is labor-intensive and therefore relatively costly. The alternative mode, self-administration by a metered dose inhaler (MDI), is less costly, but its efficacy over an entire hospitalization has heretofore not been established. Patients were enrolled after transfer to the pulmonary ward from the emergency room or intensive care units (ICU). We then randomized them to receive metaproterenol q4h either via MDI or UDN. Daily spirometry revealed that MDI and UDN were associated with equivalent bronchodilation initially and equivalent improvement at discharge. The duration of hospitalization for the two groups was also the same. Thus, the two delivery methods were equally effective. We could not attribute this equivalence to pretreatment intergroup differences or to differences in concomitant therapy with steroids, theophylline, other bronchodilators, or antibiotics. Routine use of MDI rather than UDN in all non-ICU adult patients would save $253,487 per year at our institution alone.

Prostaglandin E1 as a screening vasodilator in primary pulmonary hypertension.

Pulmonary vasodilators are variably efficacious in primary pulmonary hypertension (PPH). None has consistently improved hemodynamics enough to obviate the need for complex and potentially hazardous testing of several vasodilators. Prostaglandin E1 (PGE1), a potent, short-acting pulmonary vasodilator, was administered to seven patients with PPH in order to determine whether PGE1 could accurately predict the hemodynamic and gas exchange effects of other commonly used vasodilators. Prostaglandin E1, nifedipine and hydralazine were administered to the patients while measuring pulmonary and systemic hemodynamics and arterial blood gases. Prostaglandin E1 was easily titrated but was inconsistent as a predictor of the effects of the other vasodilators with respect to pulmonary artery pressure, cardiac output and adverse effects on arterial oxygenation. This study suggests that patients with PPH must still receive carefully monitored trials of several vasodilators to determine whether there is a beneficial response and to select the appropriate treatment.

DecisionNET: database/network support for clinical decision analysts.

DecisionNET is a proposed remote database/wide-area computer network that should cultivate quantitative approaches to medicine by providing rapid access to medical facts, literature citations, decision models, and commentary of specific use to those involved with quantitative clinical decision making. Increasing accessibility to data and providing a forum for exchange of ideas should prove to be a significant asset to clinicians, either as modelers or as clients. Further work will address specific database implementation, development of a query engine, and coordination of the communications infrastructure. DecisionNET provides a unique model for the growth and maintenance of other medical knowledge bases.

Zone 2 and zone 3 pulmonary blood flow.

In the West model of zonal distribution of pulmonary blood flow, increases in flow down zone 2 are attributed to an increase in driving pressure and a decrease in resistance resulting from recruitment and distension. The increase in flow down zone 3 is attributed to a decrease in resistance only. Recent studies indicate that, besides the pressure required to maintain flow through a vessel, there is an added pressure cost that must be overcome in order to initiate flow. These additional pressure costs are designated critical pressures (Pcrit). Because Pcrit exceed alveolar pressure, the distinction between zones in the West model becomes less secure, and the explanation for the increase in flow even in West zone 3 requires reexamination. We used two methods to test the hypothesis that the Pcrit is the pertinent backpressure to flow even in zone 3, when the pulmonary venous pressure (Ppv) exceeds alveolar pressure (PA) but is less than Pcrit in the isolated canine left caudal lobe. First, PA was maintained at 5 cmH2O, and pressure flow (P-Q) characteristics were obtained in zone 2 and zone 3. Next, with PA still at 5 cmH2O, we maintained a constant flow and measured the change in pulmonary arterial pressure as Ppv was varied. Both techniques indicated that the pertinent backpressure to flow was the greater of either Pcrit or Ppv and that PA was never the pertinent backpressure to flow. Also, our results indicate no significant change in the geometry of the flow channels between zone 2 and zone 3. These findings refine the zonal model of the pulmonary circulation.

Allergic contact dermatitis to 1,4-bis(isopropylamino)anthraquinone. Caused by a felt-tip marker pen.

Adult allergic contact dermatitis to the black ink of a felt-tip marker pen occurred in two adult subjects. In both subjects the cutaneous reaction did not require photoactivation. Patch testing with the ingredients in the black ink demonstrated cutaneous sensitivity to the black dye. Further patch testing with the components of the black dye revealed cutaneous sensitivity in both subjects to the blue component, 1,4-bis(isopropylamino)anthraquinone, commonly known as Colour Index Solvent Blue 36.

Effect of topical indomethacin and timolol maleate on intraocular pressure in normal subjects.

In a prospective randomized double-masked crossover study in ten healthy volunteers, conducted to determine if the intraocular hypotensive effect of timolol eyedrops was significantly affected by the concomitant use of the topically administered prostaglandin inhibitor, indomethacin, we found that significant ocular hypotension was achieved with timolol alone. This was not changed by the concurrent administration of indomethacin. The results provide further evidence that prostaglandins are not involved in the control of normal intraocular pressure.

The effect of body position on the respiratory rate of infants with tachypnea.

In neonatal disease states where lung compliance is reduced (e.g., inadequate resorption of fetal lung fluid or, surfactant deficiency) an infant's normally low functional residual capacity (FRC) decreases even further. Tachypnea is an efficient compensatory maneuver for the newborn. We evaluated the effect of different bed and body positions on the increased respiratory rate observed in infants with transient tachypnea of the newborn (TTN), infant respiratory distress syndrome (RDS), and bronchopulmonary dysplasia (BPD). Seventeen infants were studied (TTN, n = 6; RDS, n = 6; BPD, n = 5) in four different positions: supine flat, supine elevated, prone flat, and prone elevated. Respiratory rate and heart rate were evaluated in each position. Analysis of variance for the three patient groups showed a lower respiratory rate when the bed was elevated 20-30 degrees compared to flat (P = 0.0001), in the prone posture compared to supine (P = 0.031), and no significant difference in heart rate. The lowest mean respiratory rate occurred when patients were in the prone elevated position. The significant improvement in tachypnea seen in the prone and elevated positions was likely related to improved FRC resulting from reduced cephalad stress on the diaphragm from the abdomen. Positioning neonatal patients with respiratory insufficiency was a simple and safe therapeutic maneuver with prompt and demonstrable benefit.

Basal cell epitheliomas developing in a localized linear epidermal nevus.

A case is presented of a fifty-seven year old white man in whom an early basal cell epithelioma as well as a large ulcerated pigmented basal cell epithelioma developed from a pre-existing localized linear epidermal nevus in which there were no abnormal pilosebaceous complexes. The transition stages from a localized purely epidermal nevus to an early basal cell epithelioma and finally to a large ulcerated pigmented basal cell epithelioma are clearly illustrated, and clinicians should be alerted to the fact that this sequence of events may rarely occur.

Reinventing patient-centered computing for the twenty-first century.

Despite evidence over the past decade that patients like and will use patient-centered computing systems in managing their health, patients have remained forgotten stakeholders in advances in clinical computing systems. We present a framework for patient empowerment and the technical realization of that framework in an architecture called CareLink. In an evaluation of the initial deployment of CareLink in the support of neonatal intensive care, we have demonstrated a reduction in the length of stay for very-low birthweight infants, and an improvement in family satisfaction with care delivery. With the ubiquitous adoption of the Internet into the general culture, patient-centered computing provides the opportunity to mend broken health care relationships and reconnect patients to the care delivery process. CareLink itself provides functionality to support both clinical care and research, and provides a living laboratory for the further study of patient-centered computing.