U-type exchange in a paracentric inversion as a possible mechanism of origin of an inverted tandem duplication of chromosome 8.

A mentally retarded male with dysmorphic features was found to have a de novo 46,XY,inv dup(8) (p.23.1-->12). Confirmation of the segments duplicated in the rearrangement was achieved by biochemical analysis of glutathione reductase, which maps to 8p21.1, and DNA studies using the chromosome specific probe y-19-1D (D85131), which maps to 8p21. Assay of cathepsin B, which has been localised to 8p22, did not differ from controls with normal chromosomal constitution. DNA studies using the Defensin 1 gene probe, which maps to 8p23, showed a previously undetected deletion of that segment. We propose that the inverted tandem duplication/deletion arose as a single U-type exchange within an inversion loop.

Newborn screening for sickle cell and other hemoglobinopathies: a Canadian pilot study.

We estimated incidence of HbS disease in Quebec. It is approximately 9 cases per 100,000 births (equivalent to the incidence of the hyperphenylalanemias). Accordingly, we performed a voluntary pilot study in 9 self-identified ethnic groups; 3528 families were counselled about the relevance of newborn screening for hemoglobinopathies; and 2779 cord blood samples were collected (participation rate, 78.7%) and analyzed for Hemoglobin S and other hemoglobin variants by cellulose acetate electrophoresis. There were 95 (3.42%) positive tests on the initial (cord blood) samples, of which only 40 could be confirmed because of low participation in follow-up. We identified 8 false-positive tests; 7 had been classified initially as alpha-thalassemia trait and one as HbC heterozygosity on the first test. The relative frequency of hemoglobinopathy genes (confirmed) was: 52.5% HbS; 22.5% alpha-thalassemia; 22.5% other mutation; all but one patient with sickle cell disease were heterozygotes; the majority (71%) of HbS genes were accounted for by the 7% of screened newborns who were Black; a further 24% of the HbS genes were accounted for by 7% with Central American ancestry. Record linkage of the findings in heterozygotes for use later in life is an unsolved problem. Seventy five first-degree relatives of the 48 probands were screened in follow-up studies (64% of parents participated); 5 couples at risk for having a future child with a hemoglobinopathy were identified. Attitudes toward follow-up varied among the ethnic groups. The single family with an affected newborn (sickle cell anemia) was counselled effectively; the infant received penicillin prophylaxis.(ABSTRACT TRUNCATED AT 250 WORDS)

Speech processing studies using an acoustic model of a multiple-channel cochlear implant.

The speech perception of two multiple-channel cochlear implant patients was compared with that of three normally hearing listeners using an acoustic model of the implant for 22 different speech tests. The tests used included a minimal auditory capabilities battery, both closed-set and open-set word and sentence tests, speech tracking and a 12-consonant confusion study using nonsense syllables. The acoustic model represented electrical current pulses by bursts of noise and the effects of different electrodes were represented by using bandpass filters with different center frequencies. All subjects used a speech processor that coded the fundamental voicing frequency of speech as a pulse rate and the second formant frequency of speech as the electrode position in the cochlea, or the center frequency of the bandpass filter. Very good agreement was found for the two groups of subjects, indicating that the acoustic model is a useful tool for the development and evaluation of alternative cochlear implant speech processing strategies.

Glare disability in eyes with intraocular lenses.

For 32 eyes tested for glare disability after undergoing extracapsular cataract extraction with implantation of posterior chamber intraocular lenses, the mean contrast threshold in the presence of the glare source was 23% for undilated pupils and 31% with dilation. A regression analysis of glare scores as a function of the amount of posterior capsule opacification showed a significant (P less than .00001) association between the two.

Clinical trial of a multiple-channel cochlear prosthesis. An initial study in four patients with profound total hearing loss.

The clinical trial of a multiple-channel cochlear prosthesis was undertaken in four patients with postlingual deafness and profound total hearing loss. The results of open-set speech tests confirmed that, using electrical stimulation alone, one patient could have a meaningful conversation without resorting to lipreading (for example, this patient uses the prosthesis to converse with her husband on the telephone). The results of closed-set speech tests also suggested that a multiple-channel stimulator is more effective than a single-channel one in conveying speech information. The cochlear prosthesis was especially effective in all four patients when it was used in conjunction with lipreading, and speech-tracking tests showed that the patients could combine the information obtained from both electrical stimulation and lipreading.

Bilateral intraocular lens implantation.

A study of 1796 consecutive cataract patients in a posterior chamber intraocular lens implant (IOL) series revealed 373 patients (20.8%) who had bilateral IOLs. Visual acuity was 20/40 or better in 87% of first eyes operated and 90% in second eyes. The major cause of vision less than 20/40 was senile macular choroidal degeneration in both first and second eyes. The surgical reintervention rate was 11.8% in first eyes and 3.7% in second eyes. Ninety-two percent of patients had an interval of six months or more between surgery on the first and second eyes.

A fluorescein angiographic study of cystoid macular edema.

We performed a prospective fluorescein angiographic study on 66 patients who had undergone extracapsular cataract extractions with implantation of a Shearing posterior chamber intraocular lens. A primary posterior capsulotomy was performed in every case. The eyes were studied 11 to 23 months postoperatively. The incidence of cystoid macular edema (3%) was lower than that found in three series of cataract extractions previously reported. Extracapsular cataract extraction with either (1) a Shearing posterior chamber intraocular lens and a primary posterior capsulotomy or (2) a Binkhorst intraocular lens and an intact posterior capsule produces a lower rate of cystoid macular edema than does intracapsular cataract extraction either with a Binkhorst intraocular lens or without an intraocular lens. There was no significant difference in the incidence of cystoid macular edema in the two extracapsular series, indicating that preservation of an intact posterior capsule was not a significant factor.

Internal proteins of influenza virus: 35S-methionine peptide maps as genetic markers.

Methods are described for the preparation in vivo of 35S-methionine-labelled influenza viruses, the purifiction of the nucleoprotein (NP) and matrix (M) proteins and the separation of peptides obtained by protease digestion by two-dimensional thin-layer chromatography. The maps of the M proteins of A/Okuda/57(H2N2) and A/Finland/4/74(H3N2) were very similar overall but differed in three peptides. Hence they could be clearly distinguished. Maps of the NP proteins of the same strains showed a greater number of differences. A recombinant strain having the haemagglutinin and neuraminidase of the A/Finland/4/74 parent and the virulence of the A/Okuda/57 parent was shown to have the M and P proteins of A/okuda/57.