Prenatal and adult presymptomatic testing for Huntington's disease

The discovery of a fragment of DNA that is linked closely to the Huntington's-disease autosomal locus offers the opportunity for the presymptomatic diagnosis of this dominantly-inherited neurodegenerative disorder. Presymptomatic testing will present individuals and society with difficult choices and responsibilities. A pilot adult presymptomatic test programme is under way for SA families. Presymptomatic testing requires intensive counselling both before and after the test. A form of prenatal test, which is applicable to a significant proportion of couples with one partner at risk of Huntington's disease, is available also. As this form of prenatal test does not change the risk status of the parent, less extensive counselling is required and testing is available nationally through the SA programme. It is anticipated that other states will develop their own diagnostic programmes in the near future. This article explains the basis for the test, its accuracy and the importance of obtaining DNA from key individuals in pedigrees of Huntington's disease.     

Safety and efficacy of topical norfloxacin versus tobramycin in the treatment of external ocular infections.

Bacterial conjunctivitis appears to resolve more rapidly when treated with appropriate topical antimicrobial agents. In this multicenter, randomized, double-blind study of efficacy and safety, patients with presumed bacterial external eye infections were assigned to topical therapy with 0.3% norfloxacin or 0.3% tobramycin. A total of 120 patients were enrolled. Of the total, 65 had documented bacterial infections and were evaluable; 59 of these patients had bacterial conjunctivitis. All of the patients with documented infections were cured or improved regardless of the drug treatment regimen or in vitro susceptibility testing results. The most common bacteria isolated were Haemophilus influenzae, Streptococcus pneumoniae, alpha-hemolytic streptococci, Staphylococcus aureus, and Staphylococcus sp. No patients had serious adverse reactions attributed to their therapy. Norfloxacin ophthalmic solution seems to be a safe, effective, and appropriate agent for the treatment of bacterial external eye infections.     

Myocardial dysfunction in ankylosing spondylitis.

Echocardiographic evidence has suggested abnormalities of the myocardial function in patients with ankylosing spondylitis. In this work the cardiac function in patients with ankylosing spondylitis and in normal volunteers was evaluated. Twenty four normal volunteers and 21 patients with ankylosing spondylitis aged 18-45 were studied. None had overt cardiac disease. Cardiac function was assessed at rest with echocardiography, at rest and during supine bicycle exercise using radionuclide angiography in the left anterior oblique position following equilibration with 740 MBq of technetium-99. The subjects undertook supine bicycle exercise with 30 W increments every three minutes to the point of fatigue. Comparison of data from normal volunteers and patients with ankylosing spondylitis were made using Student's t test for independent samples or the Mann-Whitney non-parametric technique, as appropriate. Subjects were matched for age, sex, height, and weight. There were no echocardiographic differences; however, global nuclide left ventricular function showed several differences between normal volunteers and patients with ankylosing spondylitis. The peak filling rate during exercise was significantly lower in patients with ankylosing spondylitis: normal volunteers 6.5 (SD 1.2); patients with ankylosing spondylitis 5.7 (1.2). The time to reach peak filling during exercise was significantly lower in patients with ankylosing spondylitis: normal volunteers 102 (22); patients with ankylosing spondylitis 120 (23). Regional analysis also showed differences between patients with ankylosing spondylitis and normal volunteers both at rest and during exercise. In the anteroseptal region the filling fraction and peak filling rate were significantly lower in patients with ankylosing spondylitis. Most of the differences (although not all) were in the variables of diastolic function. This study shows that there are subtle abnormalities in cardiac function in patients with ankylosing spondylitis. The major abnormalities are in the diastolic function, suggesting a decrease in left ventricular compliance.     

Who is providing ambulatory care to Medicaid beneficiaries with acquired immunodeficiency syndrome in New York State?

This study examined the number of ambulatory care providers treating individuals with the acquired immunodeficiency syndrome who were Medicaid beneficiaries in New York State in 1988 and examined the distribution of this care across various practice settings. The study population was identified retrospectively in the New York State Medical HIV/AIDS Research Data Base and included a cohort of 5535 individuals with the acquired immunodeficiency syndrome who were enrolled in Medicaid in 1988 for at least 6 months after being diagnosed as having the disease and who had at least one ambulatory care encounter during the year. Ambulatory care for the study group was provided by more than 700 hospital or freestanding clinics and more than 3000 private physicians in 1988. Many sites had low caseloads; 47% of the clinics and 68% of the physicians treating this population saw only one or two patients with the acquired immunodeficiency syndrome who were enrolled in Medicaid. More than half the patients in the study group were seen most frequently in clinics for their ambulatory care during 1988. These data provide reassurance that a wide network of providers is involved in the care of patients with the acquired immunodeficiency syndrome who are Medicaid beneficiaries in New York.     

Zygomycosis requiring amputation of the hand: an isolated case in a patient receiving haemodialysis

A case of zygomycosis due to Rhizopus microsporus variety microsporus in a patient who was receiving haemodialysis is described. This infection resulted in amputation of the right hand. Criteria to identify the fungus are presented. The pathogenesis and treatment of zygomycosis are discussed.     

Object recognition versus object discrimination: comparison between human infants and infant monkeys.

Human infants (12-32 months old) and adults learned a delayed nonmatching-to-sample (DNMS) task and single- and multiple-pair discrimination tasks using nonverbal procedures previously used with monkeys. Infants learned discriminations rapidly and at a young age (12 months), but they required prolonged training and maturation before learning the DNMS task. Adults learned all tasks rapidly. After learning the DNMS task to criterion, memory performance declined systematically in an inverse relation to age. The dissociation in ability of infants on the DNMS versus discrimination tasks closely resembles the dissociation previously reported with infant monkeys (Bachevalier & Mishkin, 1984). Results from both infant humans and monkeys support a neurocognitive maturational model.     

Use of long catheters for multipatient anesthetic monitoring at high respiratory frequencies

Anesthetic gases from several patients can be monitored simultaneously with a centrally located mass spectrometer. Such monitoring requires catheters from patient to spectrometer that are several meters long. Scamman (J Clin Monit 1988;4:227–229) found that when the respiratory frequency is high, as with infants, the CO₂ signal from the patient is unacceptably distorted during passage down the catheter. This is due to Taylor dispersion of the input signal. An outline of the theory of Taylor dispersion is given. The equations describe the interaction between the velocity distribution (which, in laminar flow, is parabolic) and the radial diffusion of CO₂. This interaction keeps a tracer signal together in a pulse, as it moves down the tube with themean velocity, spreading somewhat as it proceeds. How much does an initially sharp signal become blurred? The spread of such a signal when it reaches the detector, measured in time, can be expressed in various ways. Measurement is complicated, however, by the fact that the gas pressure may fall by as much as a factor of 10 along the line. The resultant expansion and acceleration of the gas cannot be ignored. A full treatment of this complication is given elsewhere, but the following simple equation is described: {ie237-1} Typically, the spread time is up to a quarter of a second for catheters of 50 m, such as used by Scamman. This is comparable with the period of CO₂ rise and fall for infants and explains the serious distortion in wave form that Scamman found. Some distortion can be eliminated by reducing R to 0.1 or less, but the extent of this improvement is small. Ideally, for fast-breathing patients, the catheter length should be reduced to 20 m or less, if possible.     

Efficacy of autograft and freeze-dried allograft to enhance fixation of porous coated implants in the presence of interface gaps.

Autogenous cancellous bone and freeze-dried allogeneic cancellous bone were tested in a total of 41 adult male mongrel dogs. In each humerus, an implant with a commercially pure titanium fiber metal porous coating was placed in an overreamed cavity so that a uniform 3-mm gap was present between the implant and host cancellous bone. Graft material was placed in the gap of one humerus while the gap of the other humerus was left empty and served as a paired negative control. Histologically, both autograft and allograft appeared to aid repair of the defect, but quantitatively only autograft enhanced new bone formation within the defect. Treatment with autograft significantly increased the amount of bone ingrowth within the implants by nearly three-fold at 4 weeks and eight-fold at 8 weeks. The enhancing effect was recognizable as early as 2 weeks. The strength of fixation was increased by nearly seven-fold at 4 weeks and two-fold at 8 weeks in the autograft group, but this was only statistically significant at 4 weeks. Treatment with allograft did not enhance bone ingrowth at any time period, but had a small positive effect on strength of fixation at 4 weeks.