Canadian children: will today's "couch potatoes" be tomorrow's cardiac patients?

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FPs who don't practise obstetrics may still face birth-related legal action

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Spectator events: medical preparation a must

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Restrictive-type hemodynamics following valve surgery for rheumatic heart disease

Over a six-year period three patients with rheumatic valvular disease presented with congestive heart failure due to abnormalities in myocardial diastolic function. Each patient previously had been operated for mitral stenosis; one patient had additional aortic valve replacement for aortic insufficiency. The mean time for the development of symptoms following surgery was 4.7 years. In all patients, left ventricular systolic function was normal (radionuclide or angiographic ejection fraction greater than 0.50). Abnormalities in diastolic function involved the left ventricle in all patients. Biopsy material from right (one patient) and left (one patient) ventricles was nonspecific in its histologic appearance. Other disease processes, such as constrictive pericarditis and diabetic cardiomyopathy were considered to be clinically unimportant in these patients. Restrictive-type hemodynamics in patients with postoperative rheumatic heart disease may comprise a newly recognized entity.

On a wing and a prayer: health care in the Peruvian jungle

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Are medical computing and the law on a collision course?

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Meperidine-induced delirium

Despite the widespread use of meperidine as an analgesic, its potential for producing delirium has been overlooked. Six cases demonstrating meperidine-induced behavioral toxicity are reported. Toxicity was more likely when meperidine was combined with cimetidine or drugs having anticholinergic activity. Discontinuation of meperidine and substitution of morphine for analgesia were usually successful in treating the delirium. Physostigmine reversed the delirium in one patient. The authors suggest that the delirium results from the excessive anticholinergic activity of meperidine or its only active metabolite, normeperidine.

Computers in health care: we're entering a new phase

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Influence of pressure on permeability of normal and diseased muscular arteries to horseradish peroxidase. A new catheter approach

The effects of different distending pressures on permeability of dog and human arteries to horseradish peroxidase (HRP) were studied. A new catheter was employed to achieve the distention of defined vessel segments to the desired pressure. Normal dog brachial arteries were studied both post mortem and in vivo. Mildly to moderately diseased human coronary arteries were studied post mortem. A predictable linear relationship between pressure and penetration of HRP into the dog arterial media was found, using pressures of 0, 150, 300 and 500 mm Hg. Postmortem vessels were consistently less permeable than those studied in vivo. Full penetration of the media by HRP was achieved by application of 300 mm Hg pressure for 45 sec with the new catheter. When human coronary lesions were examined under these same conditions, plaques were readily demonstrated to be permeable to HRP, even to a depth of many hundreds of micrometer. Thus, penetration of arterial wall thickness by HRP (Mr 40,000 dalton) is related to the distending pressure applied. Human coronary plaques also show ready penetrance by HRP. The new catheter described allows the application of these pressures to defined segments of the arterial tree.

Confronting the prescription drug addict: doctors must learn to say no

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Fighting back: the search for a solution to prescription drug abuse

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The prescription drug sting: be careful out there

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Amniotic fluid alpha-fetoprotein levels and fetal chromosomal abnormalities

406 midtrimester amniotic fluid samples were examined for alpha-fetoprotein (AFP) levels and fetal karyotyping. 44 cases with Down syndrome, 12 with Klinefelter syndrome and 14 with other chromosomal abnormalities were diagnosed. The AFP levels were below the median value for the normal pregnancies in 38 of the 44 Down syndrome-affected fetuses. The mean AFP value was significantly lower (p less than 0.0001) in this group. No such difference was found for fetuses affected by Klinefelter syndrome or other chromosomal aberrations. Almost all of the values for the Down syndrome-affected fetuses were, however, within the normal range, thereby precluding the possibility of using this measurement as an alternative to fetal karyotyping as a screening test for Down syndrome.

Current laser dentistry

Current laser dentistry since our initial studies in 1964 is reviewed. Three areas are considered: routine dental office practice, tooth restoration, and oral surgery. For tooth restoration and oral surgery, CO2 and neodymium:YAG lasers are used and lasers are used in photodynamic therapy for oral cancer. Dental office practice today is concerned mostly with uncontrolled studies of biostimulation and requires more basic research and controlled clinical studies. The laser industry in the United States should take a more active interest in defining the applications of lasers in dentistry.

Battlefield has been the classroom for Israel's military doctors

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Effect of blood contamination on the fluorescence polarization value of amniotic fluid lamellar bodies

Estimation of fetal lung maturity by examination of amniotic fluid samples is unreliable in the presence of blood. Centrifugation of amniotic fluid at 10,000 X g separates the surfactant-containing lamellar bodies from contaminants, such as serum lipids. The influence of serum contamination of amniotic fluid was evaluated using the fluorescence polarization technique for determination of fetal lung maturity. Addition of serum changed the amniotic fluid P value of both the amniotic fluid and the lamellar body pellets in the direction of the P value of serum. After centrifugation at 10,000 X g, there was no significant difference in the P value of the pre- and postcontamination samples, demonstrating that centrifugation resulted in the removal of pulmonary nonrelevant lipids in contaminated amniotic fluid specimens. In 24 patients in whom the amniotic fluid sample was blood stained, the P value on the lamellar body pellet compared favorably to that obtained from noncontaminated samples.

Determination of fetal lung maturity by fluorescence polarization of the amniotic fluid lamellar bodies

High-speed centrifugation of amniotic fluid enables separation of surfactant-containing lamellar bodies. Fifty-three amniotic fluid samples from pregnancies of 28 to 39 weeks' gestation were examined for fetal lung maturity by measuring fluorescence polarization (P). For each sample the P value was determined at 37C on both the whole amniotic fluid and on the surfactant-containing lamellar bodies obtained by centrifugation at 10,000 X g. A close linear correlation (r = 0.80) was found between the P value of the amniotic fluid samples and that of the lamellar bodies. There was no difference in the specificity for discrimination of hyaline membrane disease cases by both methods (93.5%) with 95% confidence limits of 82.1 to 98.6%. Because high-speed centrifugation enables the selective sedimentation of pulmonary surfactant, determination of the lamellar body P value may offer a practical solution for the estimation of fetal lung maturity in amniotic fluid samples contaminated with blood.

Treatment-independent pregnancy after in vitro fertilization and embryo transfer trial

This study indicates that SP occur in a higher percentage than theoretically expected after IVE-ET treatment, but it is not conclusive as to whether the SP is independent or a result of the treatment or operative laparoscopy. Our results are in agreement with those of previous studies that have shown that SP occur with almost all kinds of infertility. We therefore reject the previous suggestion of Steptoe, who argued that to prevent ectopic pregnancy from complicating embryo replacement, preparatory electrocauterization of diseased tube should be performed. We also suggest that as long as the results of treatment are below the normal monthly spontaneous conception rate, there is justification for a prospective random study that includes all diagnoses other than BTB. Such a study might help make any future selection of patients for treatment more appropriate.

Periovulatory 17 beta-estradiol changes and embryo morphologic features in conception and nonconceptional cycles after human in vitro fertilization

Thirty-one patients who became pregnant after in vitro fertilization were compared with a matched control group of 31 patients who underwent embryo transfer but did not conceive. During the follicular phase there was no difference in the mean daily estradiol (E2) levels between the pregnant and control groups. In 95% of the women who conceived, E2 continued to rise or plateau on the day after human chorionic gonadotropin (hCG) administration; this pattern was seen in only 62.5% of the control group. There were significantly more "regular" embryos (i.e., those with symmetric blastomeres and no visible cytoplasmic fragments) replaced in patients who became pregnant, compared with the control subjects (65.6% versus 47.0%, P less than 0.05). Embryo regularity was associated with preovulatory E2 pattern; falling E2 levels on the day after hCG administration were associated with transfer of only 18.8% of regular embryos in the control group, whereas in the conceptional cycles with rising E2 levels, 61.5% of the replaced embryos were morphologically regular (P less than 0.01). These results would indicate that changes in the follicular environment as reflected by peripheral E2 levels might affect the developmental potential of the human embryo.

Differences between cystic fibrosis and normal cells in the degree of satellite association

The degree of satellite association was found to be significantly higher in phytohemagglutinin (PHA)-stimulated lymphocytes from cystic fibrosis (CF) patients than from those of control individuals. PHA-stimulated lymphocytes from obligatory heterozygotes for the CF mutant allele showed an intermediate degree of satellite association. The degree of satellite association was estimated by the frequency of cells exhibiting associations, by the number of associations per cell, and by the number of chromosomes in an association. The differences in the degree of satellite association were dependent on the concentration of colchicine used for cell arrest. These findings may assist in developing a diagnostic method for the early identification of heterozygotes for the CF allele and for prenatal detection of CF homozygous fetuses.

Brazil's Institute of Tropical Medicine: it's not pretty but it works

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Penetration of sperm from teratospermic men into zona-free hamster eggs

The ability of sperm samples from male partners of infertile couples, with isolated teratospermia (ITS), to penetrate zona-free hamster eggs was examined. The ITS patients had a significantly lower proportion of normal spermatozoa than did a control group of men of proven fertility (23.6% and 47.8%, respectively; P less than 0.001), while the mean total sperm count and the % motility did not differ between the two groups. The mean hamster egg penetration rate of sperm from ITS patients was 2.64% compared to 31.1% in the control group. A significant negative correlation was found in the ITS group between the proportion of a) abnormal forms and the ability to penetrate zona-free hamster eggs, and b) pyriform-shaped sperm and the penetration rate. Of the sperm parameters which were examined, only the morphology could be correlated with the rate of penetration.

Urinary loss of glucose, phosphate, and protein by diffusion into proximal straight tubules injured by D-serine and maleic acid

In several models of acute renal failure leakage of glomerular filtrate out of the tubule is an important pathogenetic mechanism; however, bidirectional diffusion of solute to account for certain pathophysiologic features of acute renal failure has received meager attention. Using micropuncture and clearance methods, we assessed sequentially leakage of solutes and inulin across proximal straight tubules (PST) injured by two nephrotoxins. In d-serine-treated rats with extensive necrosis of PST, the basis for glucosuria and tubular leakage of inulin was studied. Glucose absorption by the proximal convoluted tubule and glucose delivery to the PST were normal, but glucose delivery to the distal tubule was increased nearly 8-fold, indicating diffusion of glucose from interstitial to tubular luminal fluid across the necrotic PST. Total kidney inulin clearance was greatly reduced, but single nephron glomerular filtration rate, based on proximal convoluted tubule samples, was normal, indicating tubular loss of inulin. Urinary recovery of [14C]inulin infused into tubular lumina revealed that proximal convoluted tubule and distal tubule were impermeable to inulin and that inulin diffused out of the necrotic PST. The progressive return over 6 days of tubular impermeability for inulin correlated with relining of PST with new cells. In maleic acid-treated rats the site and extent of tubular necrosis and the nature of urinary loss of solutes were studied. Microdissection revealed that maleic acid caused limited necrosis of PST which averaged 7.4% of total proximal tubular length. Increased urinary excretion of protein, phosphate, and glucose and increased tubular permeability to microinfused [14C]inulin occurred with the onset of PST necrosis, and return of these abnormalities to normal correlated with the degree of cellular repair of the PST. Together these data indicate that with severe cellular injury there is bidirectional, concentration-dependent diffusion of solutes between the interstitial and tubular fluids. Thus, experimental or human toxic nephropathies should not be classified as acquired Fanconi's syndrome unless specific tubular transport defects are present.

Determination of amniotic fluid microviscosity at body temperature: a predictor of fetal lung maturity

One of the most convenient ways to determine fetal lung maturity is by measuring the fluorescence polarization (P) of the amniotic fluid at room temperature. With sensitivity fixed on 100%, specificity is relatively unsatisfactory. The present study compared the predictive power of fluorescence polarization measured at temperatures 25C (P25), 37C (P37), and 40C (P40) among 195 consecutive samples tested at both 25C and 37C, with a subgroup of 86 samples tested also at 40C. A better separation between the results for fetuses with and without hyaline membrane disease is attained at P37, demonstrated by a greater mean standardized distance (distance between P values for those patients with and the mean P value for those patients without hyaline membrane disease in unit of standard deviation of the latter; 1.597 +/- 0.528 for P25 versus 2.332 +/- 0.591 for P37). Fixing the sensitivity at 100%, the specificity of P25 and P37, were 68.9 and 94.9%, respectively; a highly significant difference (P less than .001). The specificity of P40 was 90.5%, lower than that of P37. P37 is the best predictor and adding either P25 or P40 does not improve the prediction of lung maturity. It is concluded that P37 should replace P25 as the definite index for fetal lung maturity.

The effect of pressure on the lipid microviscosity and phase transition of lung surfactant

The effect of pressure on the lipid dynamics of the rat lung surfactant was studied in liposomes made of the natural lung surfactant of the rat and of model phospholipid mixture. The determined parameter was the lipid microviscosity, monitored by the fluorescence polarization of the probe 1,6-diphenyl-1,3,5-hexatriene. Osmotic pressure of up to 47 atm, as well as hydrostatic pressure of up to 1.4 kbar, were applied at a constant temperature. The effect of pressure was monitored by the change in the lipid microviscosity of the system. The maximal change achieved with osmotic pressure at a constant temperature was only 30%. This suggests that the conversion of melted lipid to its solid phase above the lipid critical temperature requires several hundred atmospheres. Similarly, measurements of lipid microviscosity under increased hydrostatic pressure revealed transitions which occurred at above 400 atm. Since such pressures are far beyond the physiological scale, it excludes the possibility that pressure alone can be responsible for a full phase transition of the lung surfactant during respiration. Upon decompression, microviscosity of the examined lipid system was found to return to its original values, confirming the reversibility of the process.

James Welsh: Amnesty International's medical office coordinator

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Professional courtesy: my colleagues will no longer be my brothers

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Endocrinological evaluation in a case of XX male syndrome

A case of a phenotype male with 44 XX karyotype is presented. Clinical, endocrinological and anatomical findings are recorded. Serum level of FSH was elevated, LH level was normal and testosterone level was low. A subnormal response by testicular Leydig cells to hCG was observed. A dexamethasone suppression test and an ACTH test were normal. A B scan ultrasonographic examination did not show female internal genitalia, nor a hyperplasia of adrenal tissue. A review is made of the literature with theories of etiology.

Meiotic association between the XY chromosomes and unpaired autosomal elements as a cause of human male sterility

Intimate association between autosomal translocation trivalents and XY bivalents at pachytene was observed in a majority of cells of two men ascertained through primary sterility and found to be heterozygous for a 14;21 Robertsonian translocation. The association, studied by light and electron microscopy of spread first spermatocytes, was between the unpaired short arms of the normal chromosomes of the translocation trivalent and the differential axes of the XY chromosomes. In a minority of cells, this contact was not established, or not maintained, as alternative combinations between the elements available for non-homologous pairing were realized. Following a suggestion of Lifschytz and Lindsley (1972), sterility in these patients was attributed to spermatogenic arrest caused by physical contact of sex chromosomes with autosomal material and consequent interference with the normal metabolism of the sex chromosomes. Autosomal aberrations and polymorphisms, which lead to the presence of unpaired segments at meiosis, may thus play a critical role in a general mechanism of chromosomally-derived male sterility. It is proposed that such a mechanism may also be instrumental in the initiation of reproductive barriers in nature.

The doctor goes to summer camp

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Professional misconduct: does the public have the right to know?

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"House of God" author optimistic about future

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Ontario experiments with emergency paramedics

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Can Aimé Limoge sell electroanesthesia to North America?

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Chromosome analysis of multipronuclear human oocytes fertilized in vitro

In an in vitro fertilization and embryo transfer program composed mainly of patients with tubal infertility, the incidence of fertilized oocytes with multiple pronuclei was 4.3%. An attempt was made to fix such oocytes with supernumerary pronuclei in order to assess the chromosome constitution of the gametes. Nine multipronuclear oocytes containing a total of 29 pronuclei were successfully fixed before the first cleavage division, and another oocyte containing 3 pronuclei was fixed before the second cleavage division. On analysis, chromosome counts could be obtained for 28 of the 29 total pronuclei, and 24 gave informative results. Nineteen pronuclei had a normal haploid chromosome count, 2 pronuclei contained one extra chromosome, and 3 pronuclei had one chromosome missing. The presence of a Y chromosome in six pronuclei identified their paternal origin; two of the six sperm pronuclei had a 22,Y,-E chromosome constitution. Only three pronuclei could be conclusively ascertained to be maternal in origin, yet two of these were aneuploid; one pronucleus had a 24,X,+D karyotype and the second had only 22 chromosomes. Multipronuclear oocytes present ideal material for analyzing the chromosome constitution of those human gametes which can undergo fertilization in vitro.

Electroconvulsive seizures inhibit amygdala kindling: implications for mechanisms of action in affective illness

Amygdala kindling, the progressive development of seizures following repeated electrical stimulation, has been used as a model of epileptogenesis, neural memory, and the development of behavioral alterations. In an attempt to interfere with the kindling process, electroconvulsive seizures (ECS) were administered 6 h prior to or immediately after once-daily amygdala stimulation. ECS compared with sham ECS 6 h prior to kindling profoundly inhibited the development of amygdala-kindled seizures, while ECS immediately after the afterdischarge (AD) were not effective. In a second study, seven daily ECS, but not a single ECS followed by a 6-day delay, markedly suppressed established amygdala-kindled seizures compared with sham ECS controls. The generalized seizures of ECS thus appear to be paradoxically anticonvulsant to limbic seizures. Carbamazepine, a potent anticonvulsant for temporal lobe and limbic seizures in animals and man, inhibits amygdala-kindled seizures and is effective in the treatment of manic-depressive illness. The current findings suggest the possibility that the efficacy of ECS in affective illness may be, in part, related to its limbic antikindling and anticonvulsant effects.