Community-oriented medical education: comparison of tracks in Mexico and New Mexico

Most major innovations in medical education have occurred in a small number of new schools. Attempts to create change in traditional schools are far more complex. Relevant models for such change are few and there is an urgent need for institutions pioneering such changes to learn from each other's experiences. Two conventional medical schools described in this paper have attempted to create community-oriented institutional change by establishing experimental undergraduate curricular tracks. One is in a developing country, Mexico, the other in a technically developed country, the United States. These new tracks in medical education evolved independently of one another, yet they have many similarities and have experienced common problems. A formal exchange between the two schools has led to new insights in medical education and improvements to both programmes. Exchange agreements like the one reported here would be valuable for other medical schools in both developing and technically developed countries.     

Enzymatic semisynthesis of porcine despentapeptide (B26–30) insulin using unprotected desoctapeptide (B23–30) insulin as a substrate

Unprotected porcine desoctapeptide(B23–30) insulin (DOPI) and the synthetic Gly-Phe-Phe were used as substrates for the trypsin-catalyzed synthesis of despentapeptide(B26–30) insulin (DPPI). The DPPI synthesis was accompanied by a moderate oligomerization and by the formation of a side produce which was identified as a DOPI derivative having an extra peptide bond between the Gly(A1) and Arg(B22) and which was named des(23–63) proinsulin (1). Despite side reactions, the conditions were found where the overall DPPI yields were comparable to those obtained via di-Boc DOPI, and these procedures were faster and simpler since the Boc protection and deprotection steps were omitted. The reaction progress was directly monitored by HPLC.     

Changes in Hepatocyte Ploidy in Response to Chromium, Analyzed by Computer-Assisted Microscopy

Changes in Hepatocyte Ploidy in Response to Chromium, Analyzedby Computer-Assisted Microscopy. GARRISON, J.C., BISEL, T. U.,PETERSON, P., AND UYEKJ, E. M. (1990). Fundam. Appl. Toxicol.14, 346–355. BDF1 mice were given single injections ofsodium dichromate (25 mg/kg) on an acute (6 hr to 7 days) orintermediate (2-4 weeks) basis, or multiple injections (12.5mg/kg) on a chronic (4.5 months) basis. Observed hepatic changesincluded programmed cell death (apoptosis) in the periportalregion with acute exposure and fusion of liver lobes with chronicexposure. Response to chromate exposure was measured by changein hepatocyte nuclear ploidy state (e.g., the proportion ofdiploid, tetraploid, and octaploid nuclei) based on computer-assistedimaging from histological sections. The computer-assisted imagingsystem used in this study was superior to traditional methodsbecause it (1) allows rapid ploidy determinations from histologicalmaterial and (2) can be used to collect regional information.Regional differences in ploidy were seen to occur in a consistentfashion among both control and treated animals. Nuclei adjacentto the portal triad had the lowest ploidy value (highest proportionof diploid nuclei), an intermediate value was found adjacentto the central vein, and the highest ploidy was found in themidzone. These three ploidy-based zones roughly correspond tothe three functional zones of A. M. Rappaport (1973, Microvasc.Res. 6, 212–228) and W. H. Lam-ers el al. W. H. Lamers,A. Hilberts, E. Furt, J. Smith, G. N. Jonges, J. F. Van Noorden,J. W. G. Janzen, R. Charles, and A. F. M. Moorman, 1989, Hepatology,10, 72–76. Temporal changes in ploidy were seen amongcontrol animals (all zones), with young animals (56 days) displayingrelatively low ploidy values compared to older animals (184days). Chromate exposure caused increased ploidy (all zones)among animals treated on an acute basis (the youngest animals).Chromate had no apparent effect on ploidy among animals treatedfor longer periods of time, probably because of age-relatedfactors.     

Reproductive Toxicology of Aluminum in Male Mice

The reproductive toxicology of aluminum was studied in mice.Adult male mice were treated intraperitoneally with aluminumnitrate at doses of 0, 50, 100, and 200 mg/kg/day for 4 weeksbefore mating with untreated females. Decreased body weightwas seen in all aluminum-treated groups. Decreased pregnancyrate was observed in the females mated with males previouslytreated with 100 or 200 mg/kg/day of aluminum nitrate. High-dosemale mice showed significantly decreased testicular and epididymalweights, as well as significant decreases in testicular andspermatid counts and epididymal sperm counts. Spermatid countswere also reduced at 100 mg/kg/day. However, the sperm motilitywas unaffected, and the percentages of morphological normalspermatozoa in all mice exposed to aluminum were comparableto the values in control mice. Histological changes, includingnecrosis of spermatocytes/spermatids, were observed in the testesof male mice treated with 100 and 200 mg/kg/day of aluminumnitrate, whereas the tubu lar diameters were unaffected by aluminumadministration. The current study demonstrates adverse effectsof parenteral aluminum exposure on the mouse male reproductivesystem. The "no observable adverse effect level" (NOAEL) was50 mg/kg/day.     

Clinical Experience with a New Software-Based Antitachycardia Pacemaker for Recurrent Supraventricular and Ventricular Tachycardias

The Intermedics Intertach 262-12 tachycardia reversion pulse generator was implanted in 14 patients (six male, eight female, mean age at implantation 45 +/- 16 years) with recurrent symptomatic tachycardias. Six patients had atrioventricular (AV) nodal reentrant tachycardia, three patients had orthodromic tachycardia with Wolff-Parkinson-White syndrome, two had circus movement tachycardia via a concealed bypass tract, two had ventricular tachycardia, one patient had atrial flutter. Mean duration of symptoms before implantation was 8 +/- 4 years and mean number of antiarrhythmic drug trials was 3.5 +/- 1. The primary tachycardia response made consisted of autodecremental pacing in one patient, burst pacing in two patients, and adaptive scanning of the initial delay or burst cycle length in eleven patients. The secondary tachycardia response mode consisted of autodecremental pacing in four patients, burst pacing in three patients and burst scanning in four patients. Tachycardia response was automatic in all but one patient with ventricular tachycardia. During a follow-up period of 30.5 +/- 10.6 months, one patient with ventricular tachycardia died from a nonarrhythmic cause. Reinterventions were necessary due to electrode fracture in one patient and due to pacemaker software defect in another one. Two patients underwent surgical cure of their arrhythmia: one patient with atrial flutter and one patient with AV nodal reentry tachycardia, 24 months and 11 months postpacemaker implantation, respectively. Four patients required digitalis to prevent pacing induced atrial fibrillation. Other proarrhythmic effects were not encountered. The pacemaker proved to be a versatile system with reliable tachycardia detection and termination functions. It provided a valuable adjunctive therapy in these selected patients.     

Clinical Experience with the Intertach 262-12 Pulse Generator in Patients with Recurrent Supraventricular and Ventricular Tachycardia

FROMER, M., ET AL.: Clinical Experience with the Intertach 262-12 Pulse Generator in Patients with Recurrent Supraventricular and Ventricular Tachycardia. An antitachycardia pulse generator, the Intermedics Intertach 262-12 was implanted in 16 patients (14 patients with supraventricular tachycardia of various origins and two patients with recurrent ventricular tachycardia), who were not responsive to various antiarrhythmic drug regimens. The follow-up was from 6–49 months (mean 30.9 ± 13.8). Five patients had a follow-up of over 3 years. The device was used in all patients. One patient with ventricular tachycardia died from a nonarrhythmic cause. Loss of responsiveness to burst pacing was observed in 1/14 patients with supraventricular tachycardia and nontolerance of antitachycardia pacing in one patient. Overall clinical success of pacing was observed in 13/16 patients = 81%. The pacemaker proved to be a versatile system with reliable tachycardia detection and termination functions.     

A Bayesian Meta‐Analysis Comparing AngioJet® Thrombectomy to Percutaneous Coronary Intervention Alone in Acute Myocardial Infarction

Objective: The purpose of this meta‐analysis was to compare outcomes for AngioJet thrombectomy versus percutaneous coronary intervention (PCI) without thrombectomy in acute myocardial infarction (AMI) patients. Background: PCI is the preferred treatment for revascularizing the infarct‐related artery in patients with AMI. There is controversy about the benefits of thrombectomy as an adjunct to PCI. Methods: AMI studies published between January 1, 1999, and March 1, 2007, were used to compare AngioJet thrombectomy plus PCI to PCI alone. Bayesian meta‐analytic estimates were used to estimate the odds ratios (95% CI) for short‐term mortality, major adverse cardiac events (MACE), and final TIMI 3 flow. Results: The AngioJet data included 11 studies and 1,018 patients. The PCI data included 81 studies and 24,076 patients. The AngioJet group included more patients with large thrombus burden, rescue PCI after failed thrombolytic therapy, and longer symptom duration compared to the PCI group. Despite the higher risk profile of AngioJet patients, the groups had similar odds of short‐term mortality, 0.98 (0.53, 1.50), MACE, 1.25 (0.54, 2.40), and final TIMI 3 flow, 1.12 (0.70, 2.27). Conclusion: AngioJet thrombectomy results in clinical and angiographic outcomes that are similar to PCI in lower risk AMI patients. These observations suggest that AngioJet thrombectomy may reduce the additional risk associated with visible thrombus in the infarct‐related lesion.     

Grammatical dissociation during acquired childhood aphasia

Aim  We report the case of a 6-year-old female who suffered a left hemisphere stroke attributed to a genetically determined prothrombotic state. She presented a fluent speech pattern with selective difficulty in retrieving names but not verbs. An evaluation was designed to clarify whether her symptoms represented a specific impairment of name retrieval.
Method  The child undertook an experimental battery of visual naming tasks requiring the production of 52 nouns (belonging to nine different semantic categories) and 44 verbs. Her performance was compared with that of 12 healthy children, matched for age and IQ, attending a local kindergarten.
Results  The child retrieved significantly more verbs than nouns ( χ ²=16.27, p <0.01) and had a significantly lower score in noun ( t =−7.2, p <0.005), but not in verb retrieval than the comparison group. This pattern persisted when verbs and nouns were matched for oral word frequency, showing that the results could not be explained by stimuli difficulty.
Interpretation  To our knowledge, this is the first report of a grammatical dissociation in a child. It suggests that nouns and verbs are subject to different processing early in development, at least before the formal acquisition of grammar. It contradicts theories that postulate a common processing of different grammatical categories early in life.