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Biomedical subjects

A Sommer

Publications and source records attributed to A Sommer.

At least 361 records · Page 20Linked to original sources
PubMed1984

Cross-polarization photography of the nerve fiber layer.

Cross-polarized photography was used to enhance the visibility of the arcuate bundles of the retinal nerve fiber layer ( NFL ). A fundus camera (Zeiss) was modified to accept a linear polarizing filter in front of the flash and another polarizing filter in front of the film plane. The azimuths of the two filters were kept at right angles to one another. Cross-polarized photographs were taken of the NFL of seven normal eyes and 18 eyes with ocular hypertension. The polarizers were rotated together to obtain four different orientations, equally spaced through 90 degrees. The manner in which visibility of the arcuate fibers was enhanced varied consistently with the orientation of the polarizing filters. Cross-polarization accentuated apparent defects in the NFL when compared with standard red-free illumination.

Adult↗
PubMed1984

Detection of ocular surface abnormalities in experimental vitamin A deficiency.

Hypovitaminosis A is the major cause of childhood blindness in many developing countries. Unfortunately, serum vitamin A levels do not accurately reflect liver stores, and there is no good objective test for detecting early, physiologically important deficiency. The purpose of this study was to determine if we could detect ocular surface abnormalities in the eyes of vitamin A-deficient rabbits at early stages of xerophthalmia. Cellulose acetate filter strip impressions were taken serially from the bulbar conjunctiva of vitamin A-deficient rabbits every two weeks, beginning eight to 12 weeks before keratinization of the corneal or conjunctival epithelium was clinically apparent. The percentage of light microscopic fields containing goblet cells decreased, and the percentage of fields containing enlarged epithelial cells increased in a linear fashion, beginning at least four to six weeks before the clinical changes. The results indicate that this technique may be of potential usefulness as a screening tool for early xerophthalmia.

Animals↗
PubMed1984

Evaluation of nerve fiber layer assessment.

More than 1,400 eyes with either ocular hypertension glaucomatous visual field loss, or normal pressures and fields (controls) were studied prospectively in standardized, masked fashion. The appearance of the nerve fiber layer was evaluated independently from red-free photographs with the discs blocked-out by two observers. The vast majority of photographs could be evaluated, the proportion varying with the observer and with the age and clinical status of the subject. Sensitivity (proportion of glaucomatous eyes with nerve fiber defects) and specificity (proportion of normal control eyes without defects) averaged 80% to 94%, varying with the observer and with the age, race, and severity of field loss. In two thirds of presumed false-positive eyes, but only 5% of true-positive eyes, the abnormalities were limited to focal slitlike defects. The prevalence of nerve fiber defects in eyes with elevated pressure and normal visual fields was similar to that in control eyes, approximately 10%. However, the proportion of eyes in which these defects included diffuse loss was considerably higher among the hypertensive eyes.

Adult↗
PubMed1984

Apnea and sudden unexpected death in infants with achondroplasia.

Thirteen infants with achondroplasia and sudden unexpected death or unexplained apnea were discovered through nonsystematic retrospective case collection. Most were initially thought to have died from sudden infant death syndrome. However, historical and pathologic findings suggest that many of these infants had apnea and sudden unexpected death secondary to acute or chronic compression of the lower brainstem or cervical spinal cord. Infants with achondroplasia evidently are at considerably increased risk for such deaths between 1 month and 1 year of age. Appropriate intervention, given these previously unrecognized risks, may include cervical restraint, polysomnographic evaluation, and apnea monitoring.

Achondroplasia↗
PubMed1984

Ocular BB injuries.

Data from the United States Consumer Product Safety Commission indicate that air-powered guns were responsible for 22,800 injuries treated in emergency rooms during 1981, of which 1255 were eye injuries. From 1970 to 1981, 32 patients have undergone surgical intervention at the Wilmer Eye Institute for airgun-related eye injuries. Of the 22 patients with penetrating injuries from the pellets, 19 eyes were enucleated; final vision in the three remaining eyes was worse than 5/200. Of seven patients with nonpenetrating injuries, six had final vision of 20/40 or better. All three patients with penetrating injuries from shattered spectacle lenses had final vision of 20/40 or better. Histopathologic examination of the enucleated specimens demonstrated severe disruption of intraocular contents, particularly posteriorly. Despite the potential ocular dangers of airguns, only 11 states have enacted legislation that regulates their sale or use. BB injuries represent a devastating form of ocular trauma which can be prevented by adoption and enforcement of appropriate legislation.

Adolescent↗
PubMed1984

Investigations of the influence of the content of plant crude protein in the ration on the utilisation of urea in dairy cattle. 5. 15N-fractions in the blood of lactating cows given 15N-urea intraruminantly.

The incorporation of urea-15N (given as an intraruminal drench or infusion) into plasma urea and protein of dairy cows fed isoenergetic rations with different levels of plant protein (9, 11, 12, 14, 15 and 17% in DM) was investigated. A nonlinear and asymptotic dependence between the plasma concentration of urea and protein level in the ration was stated. The availability of dietary urea-15N for plasma urea for 48 hours after administration was lowest in cows fed with low protein rations (9 and 11% of plant protein). On the contrary the highest incorporation of urea-15N into plasma protein of these animals was observed. The possible explanation of these results is presented.

Animals↗
PubMed1984

Investigations about influence of the content of plant crude protein in the ration on the utilization of urea in dairy cattle. 6. Digestive enzymes and their interactions in contents of proximal small intestine.

Forty-two samples were taken from the contents of the proximal small intestine of two lactating dairy cows fitted with re-entrant duodenal cannula. Most samples were free of detectable amylase activity. The (chymo)trypsinogen present was only partially activated to (chymo)trypsin. The activation was continued in vitro: slowly at the original pH of the samples (between pH 2.8 and 4.2), and faster after neutralization or a slight alkalinization. The effect of Ca, EDTA and soybean inhibitor on the activation of trypsinogen was also studied. The pancreatic enzymes were inactive in the acid pH range of the samples, but pepsin was markedly active. At pH 3.8 casein was digested rapidly by purified pepsin and slowly by the samples (agar-plate experiments). In model experiments performed with purified enzymes, pepsin digested (chymo)trypsin rapidly at pH 1-2 and slowly at pH 3.8. In the intestinal juice (chymo)trypsin and their zymogens seemed to be unaffected by pepsin under the conditions of the samples. It is concluded that the conditions prevailing in the duodenum/upper jejunum of the experimental cows account for a gastric-type digestion, despite the presence of pancreatic enzymes. In vivo the intestinal contents pass in distal direction. Meanwhile the pH of the chyme gradually increases and gives rise to first an increase of enterokinase activity accounting for a faster activation of the zymogens; second a start of function of activated pancreatic proteases and third a gradual decrease of pepsin activity and finally to its irreversible denaturation. Thus the development of intestinal type digestion is delayed in ruminants.

Animals↗
PubMed1984

Increased risk of respiratory disease and diarrhea in children with preexisting mild vitamin A deficiency.

Preschool-age rural Indonesian children were reexamined every 3 months for 18 months. An average of 3135 children were free of respiratory disease and or diarrhea at the examination initiating each of the six, 3-month follow-up intervals. Children with mild xerophthalmia (night blindness and/or Bitot's spots) at the start and end of an interval developed respiratory disease and diarrhea at twice (p less than 0.001) and three times (p less than 0.001) the rate, respectively, of children with normal eyes during the same interval, independent of age and anthropometric status (weight for length). The risk of respiratory disease and diarrhea were more closely associated with vitamin A status than with general nutritional status. These results may explain much of the excess mortality recently reported for mildly vitamin A-deficient children.

Child↗
PubMed1984

Preaxial polydactyly type 4: variability in a large kindred.

A five generation family with type 4 preaxial polydactyly is reported. The 21 affected individuals demonstrated variability in expression without apparent sex influence and penetrance which was complete. The deformities were more severe in the feet than the hands. Anteroposterior flatness of the thumbs was the only manifestation of the trait in the hands of several affected family members.

Adult↗
PubMed1984

Changing indications for cataract surgery.

Despite the fact that two community-based surgeons switched from routine intracapsular cataract extraction to planned extracapsular cataract surgery and routine implantation of posterior chamber lenses, they did not materially increase the size of their surgical load or change their indications for cataract surgery. In contrast a similar change in surgical technique by two high-referral hospital-based surgeons was associated with a marked increase in operative rates and increased preoperative acuity. A significant proportion of this change appeared to represent reduced reluctance toward monocular cataract surgery. By eliminating the aniseikonia of monocular aphakic and visual distortion of aphakic spectacle correction, use of IOLs appears to have contributed to changing indications for cataract surgery among some ophthalmologists. A larger, more comprehensive study would be needed to determine the full extent of these trends.

Aged↗
PubMed1983

Increased mortality in children with mild vitamin A deficiency.

An average of 3481 preschool-age rural Indonesian children were re-examined every 3 months for 18 months. The mortality rate among children with mild xerophthalmia (night blindness and/or Bitot's spots) was on average 4 times the rate, and in some age groups 8 to 12 times the rate, among children without xerophthalmia. Mortality increased, almost linearly, with the severity of mild xerophthalmia (night blindness, Bitot's spots, and the two combined). These relations persisted after stratification for respiratory disease, wasting, gastroenteritis, pedal oedema, and childhood exanthems. Mild vitamin A deficiency was directly associated with at least 16% of all deaths in children aged from 1 to 6 years. These results suggest that mild xerophthalmia justifies vigorous community-wide intervention, as much to reduce childhood mortality as to prevent blindness, and that night blindness and Bitot's spots are as important as anthropometric indices in screening children to determine which of them need medical and nutritional attention.

Anthropometry↗
PubMed1983

Identical multiple congenital anomalies/mental retardation (MCA/MR) syndrome due to del(2)(q32) in two sisters with intrachromosomal insertional translocation in their father.

We report two sisters with a deficiency of band 2q32 that resulted from meiotic crossover events in their father, who is a balanced, intrachromosomal insertional translocation heterozygote. This three-break rearrangement involving a single chromosome is among the rarest class of human structural chromosome abnormalities. A review confirms the theoretically predicted high risk of unbalanced progeny for such translocation heterozygotes. Fertility of carriers seems to be unimpaired in either sex. Available information is insufficient to define the effect of insertional translocation on homologue pairing, crossover frequency, and other meiotic phenomena.

Abnormalities, Multiple↗
PubMed1983

Previously undescribed syndrome of craniofacial, hand anomalies, and sensorineural deafness.

We describe in a mother and her infant daughter a previously unreported syndrome of unusual craniofacial, hand, and digital anomalies. Both mother and child have a flat facial profile, hypertelorism, hypoplastic nose with slit-like nares, and a sensorineural hearing loss. Common radiographic manifestations include small maxilla, absent or small nasal bones, and ulnar deviation of the hands. This is either an autosomal dominant or X-linked trait.

Abnormalities, Multiple↗