Dips on Békésy or audioscan fail to identify carriers of autosomal recessive non-syndromic hearing loss

Békésy and audioscan sweep audiometry tests were carried out in 24 presumed obligate carriers of autosomal recessive non-syndromic hearing loss and 30 sex and age appropriate controls, with a view to defining the most expedient criteria for dips on either test in respect of possible carrier detection. On Békésy, dips with a minimum depth of 22.5 dB generated the greatest difference between carriers and non-carriers, while on audioscan, the criterion of a minimum dip depth of 15 dB provided the best discriminant. Using these criteria, the prevalence of dips was also evaluated in 8 unaffected siblings and 24 age appropriate control subjects. The findings both in the adult and the paediatric groups do not support the hypothesis that the presence of dips, either on Békésy or audioscan, is linked to the carrier state in ARNSHL.

Reconstruction of complex chest wall defects

BACKGROUND

Reconstruction of complex chest wall defects represents a major challenge and requires close cooperation between the cardiothoracic and reconstructive surgeon to achieve an optimal outcome and reduce the incidence of complications. The principles of chest wall reconstruction include control of infection, local wound care, wide debridement of all necrotic and devitalized tissues, obliteration of all residual cavities and spaces with well-vascularized tissues, reestablishment, when necessary, of the continuity and skeletal stability of the chest wall, and immediate or early definitive coverage of all defects with well-vascularized tissues.

METHODS

This paper is based on our experience with 113 patients who underwent chest wall reconstruction for a variety of defects resulting from infection, trauma, tumor extirpation, and radionecrosis. All patients were treated with a variety of muscle flaps and/or omentum which provided obliteration of dead space and coverage. Seven patients with large anterolateral defects required additional skeletal stability with synthetic patches or mesh.

RESULTS

88.6% of patients healed without significant problems. 8.8% had major complications requiring reoperation and prolonged hospitalization while 4.4% had minor complications.

CONCLUSIONS

Based on long-term experience, we believe that currently the use of well-vascularized tissue is the method of choice for reconstruction of complex chest wall defects. This provides stable coverage, reduces hospital stay, and thus lowers overall care cost for these patients.

Atrial Pacing May Decrease the Incidence of Atrial Fibrillation Following Coronary Artery Bypass Graft Surgery

At the Montreal General Hospital in 1994, the incidence of atrial fibrillation (AF) following coronaryartery bypass graft (CABG) surgery was 30%. With the goal of reducing the incidence of thiscomplication, 20 patients (15 males and 5 females) undergoing CABG surgery were studied prospectively for the occurrence of AF following a three-day "on demand" atrial pacing at 90 beats-per-minute. The age range of the group was 39 to 79 years, with a mean age of 60 and a median age of 63. Two patients were categorized in NYHA class II, 13 in class III, and five in class IV. Of the latter five, two patients received intravenous nitroglycerin preoperatively. ß-blockers were taken pre-operatively by 13 patients, Ca2+ channel blockers by 12, and ACE inhibitors by two. Only one patient had suffered a myocardial infarction within the last year. Preoperative ejection fractions ranged from15 to 60% with a mean of 45%. In all cases, the CABG operation achieved complete revascularizationusing left internal mammary artery (LIMA) grafts in addition to saphenous vein grafts. The averagenumber of bypasses performed was 3.15. Cardiac arrest was induced using intermittent cold bloodcardioplegia, and cardiopulmonary bypass time averaged 60 minutes. Aortic occlusion time averaged36 minutes. Intraoperative inotrope use was infrequent, used intraoperatively with two cases requiringneosynephrine, one case requiring levophed, and one case requiring dobutamine. Post-pacing cardiacassessment revealed non-specific T wave abnormalities in five (25%) of patients, but no patient showedany evidence of acute myocardial infarction. In no cases did any complications related to the atrialpacing develop in the postoperative period. The results reveal that only two patients (15%) experiencedAF following, and one during, the three-day regimen of atrial pacing. Thus, this study providespreliminary evidence of a decrease in the incidence of post-CABG AF using atrial pacing.

Early pathologic and biochemical changes in Creutzfeldt-Jakob disease: study of brain biopsies

We examined brain biopsy tissue from five patients with a neurologic syndrome consistent with Creutzfeldt-Jakob disease using Western blot analysis and immunohistochemistry for the detection of protease-resistant prion protein, in addition to histopathologic examination. Our results indicate that the formation of protease-resistant prion protein is an early event in disease pathogenesis and Western blot analysis can detect protease-resistant prion protein in the absence of structural lesions using a small amount of brain biopsy tissue.

Pontine lesions in idiopathic narcolepsy

Three patients had longstanding (37 to 50 years), highly disabling narcolepsy, poorly controlled by treatment. The clinical histories were typical, consisting of sleepiness, cataplexy, sleep paralysis, hypnagogic hallucinations, disturbed nocturnal sleep, and HLA-DR2 tissue typing. Polygraphic findings confirmed the diagnosis. Neurologic examination, spinal fluid, and evoked potentials were normal. On MRI scanning, all three patients showed overlapping bilateral and symmetric brainstem T2 hyperintensities circumscribed to the ventrolateral aspect of the midrostral pons. The nature of the lesions remains uncertain but their location corresponded to the pontine oral reticular formation, where the neuronal network generating REM sleep is located. This is the first report of MR signal abnormalities in patients with idiopathic narcolepsy and suggests a causal relationship between the disease and the central pontine lesions.

Relationship between increased peak oxygen uptake and modifications in skeletal muscle metabolism following rehabilitation after myocardial infarction

PURPOSE

Rehabilitation after myocardial infarction produces an increased peak oxygen uptake (VO2peak). This study investigates the relationship between the modifications in skeletal muscle metabolism and the modification in VO2peak induced by a standard program of physical training following a myocardial infarction.

METHODS

Seventeen patients (14 male, 3 female) were studied by phosphorus 31(31P) magnetic resonance spectroscopy after the acute phase of a myocardial infarction and after 2 months of rehabilitation. Changes in calf muscle pH, phosphocreatine, and inorganic phosphates were measured at rest and during a plantar flexion-type incremental workload protocol. Calf muscle pH, phosphocreatine/(phosphocreatine + inorganic phosphates), and inorganic phosphates/phosphocreatine ratios were compared at the highest identical workload attained in both studies. The VO2peak (mL/kg/min) was determined during a cycle stress test.

RESULTS

At the highest identical workload attained in both tests, the ratio phosphocreatine/(phosphocreatine + inorganic phosphates) was significantly higher (0.48 +/- 0.15 to 0.57 +/- 0.18: P < .001), and the ratio inorganic phosphates/phosphocreatine was lower (1.38 +/- 1.14 to 0.99 +/- 0.87: P < .01). After rehabilitation, no difference was observed for the pH at stress (6.83 +/- 0.16 to 6.91 +/- 0.14: not significant [NS]). The increase in the VO2peak was significant after rehabilitation (24 +/- 9 to 29 +/- 11 mL/kg/min: P < .001). The VO2peak improvement induced by the physical training was correlated with the increase in the phosphocreatine/(phosphocreatine + inorganic phosphates) (r = 0.818, P < .001).

CONCLUSIONS

The reduction in phosphocreatine depletion indicated that the oxidative capacity of the skeletal muscle was improved during the rehabilitation. The good correlation between the indexes of skeletal muscle metabolism and VO2peak suggests the peripheral effect of training.

Diastolic or systolic left and right ventricular impairment at moderate doses of anthracycline? A 1-year follow-up study of women

A prospective study was carried out to assess the early and later alterations in left and right ventricular diastolic and systolic function after the termination of anthracycline therapy. In 33 women without cardiac disease who were treated by anthracycline therapy, cardiac function was evaluated by radionuclide angiography before the treatment (T0) and 1 month (T1) and 12 months (T12) after the end of the treatment. Cardiac function was assessed by radionuclide measurement throughout treatment. Analysis of ejection fraction (EF), peak ejection rate (PER), time to PER (TPER), peak filling rate (PFR) and time to PFR (TPFR) was performed before and after treatment. To normalise radionuclide measurements of the ventricular diastolic function, the ratio of the PFR and the EF and the ratio of the PFR and the PER were calculated. No patient developed symptomatic congestive cardiac failure. One-way analysis of variance showed a significant decrease in the three parameters (EF, PER, PFR) over time only for the left ventricle (LV); no significant alterations appeared for the right ventricle (RV). The EF of the LV decreased from 59%+/-5% at T0 to 57%+/-6% at T1 and 56%+/-5% at T12. The PER of the LV fell from 3.03+/-0.40 end-diastolic volume per second (EDV/s) at T0 to 2.79+/-0.47 at T1 and 2.78+/-0.43 at T12. The PFR of the LV dropped from 2.99+/-0.43 EDV/s at T0 to 2.62+/-0.44 at T1 and 2.56+/-0.42 at T12. For the normalised ratios, no differences were observed. Significant differences were found for EF, PER and PFR between T0 and T1, and between T0 and T12, but no difference was found between T1 and T12. This report shows simultaneous impairment of the systolic and diastolic LV radionuclide parameters at 1 and 12 months after anthracycline therapy without alteration in the RV function.

Teaching model for closure of oronasal fistula and bone grafting of the maxilla

Secondary bone grafting of the maxilla and closure of the residual oronasal fistula at the stage of transitional dentition has become a well-accepted treatment modality. This procedure, in conjunction with orthodontic treatment, has been incorporated into the management protocol of many cleft teams around the world in an effort to further improve functional and esthetic habilitation of patients with unilateral or bilateral clefts of the lip, alveolus, and palate.

MR perfusion imaging of the kidney pre- and post-dipyridamole stress

Animal studies have demonstrated that renal MR contrast enhancement depends on the timing of image acquisition. Limited human studies have demonstrated effects of dipyridamole (DP) on total renal perfusion. This study assessed the effect of DP on total and regional renal perfusion using gated perfusion MRI for patients undergoing DP stress. Five subjects with no evidence of renal ischemia were examined at rest and after DP stress. Rest MRI images in the left kidney were acquired using electrocardiogram (ECG)-gated MR: turbo fast low-angle shot (FLASH); echo time (TE) = 12, repetition time (TR) = 6, flip angle = 12, inversion time (TI) = 100) 10 to 45 seconds after injection of gadopentetate dimeglumine. Stress was induced in the MRI scanner (DP, .56 mg/kg over 4 minutes) followed by stress MRI after a second bolus of gadopentetate dimeglumine in the same position and identical time intervals. MR signal in the whole left kidney and renal medulla and cortex pre- and post-DP demonstrated a 70% depression of total renal perfusion with relative preservation of cortical perfusion at the expense of medullary perfusion. Post-DP MR images demonstrated a decrease in cortical perfusion with an additional 29% depression of medullary perfusion (P < .001) with respect to cortical perfusion. Turbo FLASH MRI can provide adequate time and spatial resolution to demonstrate changes in renal perfusion. Depression of renal medullary perfusion after DP appears to be caused by the intrarenal effect of DP and may have clinical impact.

Acute and longer term effects of meso-2,3 dimercaptosuccinic acid (DMSA) on the behavior of lead-exposed and control mice

We investigated the effect of chelating agent meso-2,3 dimercaptosuccinic acid (DMSA) on spatial learning and forced-swim immobility in Binghamton Heterogeneous Stock (HET) mice. Forced-swim immobility (characterized by increasingly frequent bouts of complete motionlessness in a forced-swim test, i.e., behavioral despair) is reduced by exposure to lead. In Experiment 1, male and female HETs (n = 81) were assigned to lead-exposed (0.5% lead acetate ad lib in drinking fluid), pair-fed (PF), or water control groups. Six weeks after the termination of lead exposure, half of each group was injected intraperitoneally (IP) with 50 mg/kg DMSA or vehicle once per day for 5 days. Following treatment, all animals were tested for acquisition and extinction in the Morris Water maze, followed by immobility testing in an inescapable forced-swim task. Neither Pb nor DMSA affected Morris maze performance. However, consistent with previously published work, Pb reduced immobility in the forced-water swim relative to both PF and water controls. Additionally, lead-exposed males, but not females, showed sustained improvement following DMSA treatment on immobility measures. Experiment 2 was designed to demonstrate the effect of the above DMSA protocol on blood-Pb, and also examined the immediate effects of DMSA on immobility during treatment. Thus, in Experiment 2, animals were exposed to an identical Pb and DMSA treatment protocol, but the effects of DMSA on immobility during the course of DMSA treatment were measured, and animals were sacrificed immediately after treatment so that blood-Pb measures could be taken. Under these circumstances, DMSA markedly reversed the lead-induced reduction in immobility immediately during the treatment phase. Although DMSA clearly reduced blood-lead in males, its influence on female blood levels was far less. Taken together, the data from these experiments suggest that DMSA ameliorates lead-induced immobility changes in mice, but that gender may modulate DMSA's effect on blood-lead and longer-term behavioral effects. However, further work is needed to clarify the role of gender in response to DMSA.

The surgical dilemma of the malunited calcaneal joint depression fracture: the VAMC Miami experience

During the period of October 1985 through March 1995, 25 patients presented to the Veterans Affairs Medical Center, Miami with a chief complaint of chronic pain status post calcaneal joint depression fracture. Their acute injury was treated conservatively at this and various other institutions. Nine patients were managed conservatively with orthotics, University of California Biomechanics Laboratory braces (UCBLs), shoe modification, or prosthetics. Sixteen patients underwent hindfoot fusions. Good to excellent results were obtained in 15 of the 16 fusions. The remaining patient, having an isolated subtalar fusion, was later diagnosed with multiple sclerosis. Proper evaluation of the chronic pain patient is critical when mapping out an appropriate treatment plan. Hindfoot arthrodesis with soft tissue decompression is a successful tool in eliminating chronic pain due to malunited depression fractures.

Randomized, double-blind, placebo-controlled dose-ranging study of tirofiban (MK-383) platelet IIb/IIIa blockade in high risk patients undergoing coronary angioplasty

OBJECTIVES

The objectives of this double-blind, placebo-controlled, randomized dose-ranging study were 1) to examine the safety and tolerability of tirofiban (MK-383), a new nonpeptide platelet IIb/IIIa receptor antagonist, on a background of intravenous heparin and aspirin therapy; 2) to study the pharmacodynamics and pharmacokinetics of tirofiban; and 3) to evaluate the incidence of adverse cardiac outcomes (urgent repeat revascularization, myocardial infarction and death) with tirofiban versus placebo in a high risk subset of patients undergoing coronary angioplasty.

BACKGROUND

Abrupt vessel closure complicates 4% to 8% of angioplasty procedures. Recent data have suggested that agents that antagonize the platelet glycoprotein IIb/IIIa receptor may reduce the incidence of adverse ischemic outcomes after coronary angioplasty.

METHODS

Seventy-three patients received tirofiban in three sequential dose panels and 20 patients received placebo. Patients within each panel were randomized to receive either tirofiban or placebo in a 3:1 randomization design. Bolus doses of 5, 10 and 10 microg/kg and continuous infusion (16 to 24 h) doses of 0.05, 0.10 and 0.15 microg/kg per min were administered in panels I, II and III, respectively. Patients received concomitant heparin and aspirin for the angioplasty procedure. Data on patients receiving placebo (heparin and aspirin only) were pooled across panels for comparisons. The pharmacodynamic effect of tirofiban on ex vivo platelet aggregation to 5 micromol/liter adenosine diphosphate (ADP) and bleeding times were measured. Clinical outcomes were assessed in all patients, but the power to detect clinically meaningful differences (a one-third reduction in clinical events) between groups was limited (5%).

RESULTS

Tirofiban was associated with a dose-dependent inhibition of ex vivo ADP-mediated platelet aggregation that was sustained during intravenous infusion and resolved rapidly after drug cessation. Adverse bleeding events, largely related to vascular access site hemorrhage, were slightly increased at the highest dose. Adverse clinical outcomes were infrequent in all patients and were not different among the small number of patients within each group.

CONCLUSIONS

This study establishes a rational and generally well tolerated dosing regimen for administration of tirofiban as adjunctive therapy in high risk angioplasty patients. The impact of tirofiban on adverse clinical outcomes after angioplasty awaits definition by a larger clinical trial.

Clinical practice guidelines. New-to-practice family physicians' attitudes

OBJECTIVE

To examine the attitudes toward clinical practice guidelines of a group of family physicians who had recently entered practice in Ontario, and to compare them with the attitudes of a group of internists from the United States.

DESIGN

Mailed questionnaire survey of all members of a defined cohort.

SETTING

Ontario family practices.

PARTICIPANTS

Certificants of the College of Family Physicians of Canada who received certification in 1989, 1990, and 1991 and who were practising in Ontario. Of 564-cohort members, 395 (70%) responded. Men (184) and women (211) responded at the same rate.

MAIN OUTCOME MEASURES

Levels of agreement with 10 descriptive statements about practice guidelines and analyses of variance of these responses for several physician characteristics.

RESULTS

Of respondents in independent practice, 80% were in group practice. Women were more likely to have chosen group practice, in which they were more likely to use practice guidelines than men. Generally favourable attitudes toward guidelines were observed. Physician characteristics occasionally influenced agreement with the descriptors. The pattern of agreement was similar to that noted in the study of American internists, but, in general, Ontario physicians were more supportive.

CONCLUSIONS

This group of relatively new-to-practice Ontario family physicians shows little resistance to guidelines and appears to read less threat of external control in them than does the US group.

Endoglin (CD105) expression in non-neoplastic and neoplastic human tissues and human cancer cell lines

Endoglin is an integral membrane glycoprotein that binds TGF-beta(1,3) with high affinity and is thought to play an important role in modulating the interaction of TGF-beta with its cell surface receptors. In this study a recently characterized monoclonal antibody (29-G8) recognizing endoglin was used to examine expression in a variety of human tissues and human cancer cell lines. Formalin-fixed, paraffin-embedded sections were examined by light microscopy and cell lines were analyzed by now cytometry. Immunostaining was noted in a variety of non-neoplastic epithelia from different organs; most of the neoplastic tissues surveyed also demonstrated prominent immunoreactivity for 29-G8. Flow cytometric analysis of the cell lines revealed strong 29-G8 immunoreactivity in almost all lines examined. Our results suggest that endoglin expression is much more ubiquitous than was previously thought and that endoglin may play a role in modulating TGF-beta binding activity in a variety of normal and neoplastic human tissues.

Reduction of high-grade spondylolisthesis using Edwards instrumentation

STUDY DESIGN

Sixteen patients with high-grade spondylolisthesis (Grade III or higher) who underwent posterior decompression and reduction using the Edwards Modular Spine System (Spinal System Ltd., Baltimore, MD) were reviewed clinically and radiographically.

OBJECTIVES

This study was undertaken to determine the efficacy of one specific reduction technique to treat patients with high-grade spondylolisthesis where there has been a loss of sagittal balance, intractable pain, and/or neurologic deficit.

SUMMARY OF BACKGROUND DATA

The average age of our patients was 20 years. Preoperative slippage averaged 89%; preoperative slip angle averaged 50 degrees. Indications for surgery were back and leg pain, progression of slippage (in 9 patients), and/or the inability to stand upright with the knees straight.

METHODS

Pre- and postoperative radiographic films were reviewed. The percent slip and the slip angle were measured pre- and postoperatively. Clinical data were obtained via chart review, telephone interview, and/or office visit.

RESULTS

The average preoperative slip was 89%; postoperatively, the average slip was 29%. Slip angle averaged 50 degrees preoperatively and improved to a postoperative average of 24 degrees. Three patients had neurologic impairment postoperatively; one did not resolve. Four patients had hardware failure; all were revised. Ten patients had an excellent result, 5 patients had a good result, and 1 patient had a fair result. The average follow-up was 3.8 years.

CONCLUSION

This procedure is technically demanding and is subject to the known risks of surgical treatment for high-grade spondylolisthesis. For select patients, it may be effective for reducing severe deformity and can be expected to afford good to excellent results. Improved sacral fixation may reduce the rate of hardware-related complications.

Transcriptional activation of the Cdk inhibitor p21 by vitamin D3 leads to the induced differentiation of the myelomonocytic cell line U937

The hormonal form of vitamin D, 1,25-dihydroxyvitamin D3, acting through its cognate nuclear receptor (vitamin D3 receptor, VDR) will induce myeloid leukemic cell lines to terminally differentiate into monocytes/macrophages. Because VDR acts by transcriptionally regulating responsive genes in a ligand-dependent manner, we sought target genes of the receptor that initiate, the differentiation process in response to ligand. We screened a cDNA library prepared from the myelomonocytic U937 cell line with probes generated from either 1,25-dihydroxyvitamin D3-treated or untreated cells. We report here that a candidate clone that hybridized differentially is the Cdk inhibitor p21WAF1, CIP1. Furthermore, we show that p21 is transcriptionally induced by 1,25-dihydroxyvitamin D3 in a VDR-dependent, but not p53-dependent, manner, and we identify a functional vitamin D response element in the p21 promoter. Transient overexpression of p21 and/or the related Cdk inhibitor p27 in U937 cells in the absence of 1,25-dihydroxyvitamin D3 results in the cell-surface expression of monocyte/macrophage-specific markers, suggesting that ligand-modulated transcriptional induction of the p21 gene facilitates the induced differentiation of this monoblastic cell line. We believe that this is the first report demonstrating that the ectopic overexpression of a Cdk inhibitor such as p21 or p27 directly leads to a terminal differentiation program.

Efficiency in Israel Defence Forces Dental Labs: assessing the need for privatizing publicly provided services

In the last 10 to 15 years, privatization has been used as a policy instrument to reduce the involvement of the public sector in the provision of a variety of services. The purpose of this paper is to discuss models of privatization in the dental technician market and to report on the findings of an analysis of the functioning and efficiency of such services within the framework of the Israel Defence Forces (IDF). We also develop a method for assessing the quality and efficiency with which such services are produced and assess the need for privatization of the service. Currently, the IDF employs a mixed model of privatization whereby some dental technician services are produced in-house and others are contracted out to the civilian private market. A comparative quantitative analysis of the efficiency, quality, and cost of services indicates that the civilian labs are able to produce prosthetic services at a lower cost per unit of output and at a higher level of quality than are the IDF labs. The highly competitive nature of the industry as well as the relative ease with which the IDF could monitor the quality of service further supports the case for privatization of the entire service. The analysis and method described in this paper can serve as a paradigm for evaluating dental technician services in a variety of settings.