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Biomedical subjects

M Hirsch

Publications and source records attributed to M Hirsch.

At least 163 records · Page 9Linked to original sources
PubMed1980

The development of the irido-corneal angle in the chick embryo.

The iridocorneal angle of the chick embryo was examined by scanning electron microscopy from the 7th day to the 19th day of development. The mesodermal tissue situated between the corneal endothelium and the iris differentiated into trabecular cells. These cells formed a strip on the 9th day and enlarged on the 13th day to form long cellular fibres. The trabecular meshwork was recognizable on the 15th day and reached full development only on the 19th day. The development of the trabecular meshwork was probably much earlier than is usually described. It began with differentiation of the corneal endothelial cells and these cells acquired a multipolar cell body with long cellular processes. The last stage is probably regulated to avoid an abnormal development of the angle structure. These results can be correlated with those obtained in the morphological examination of the structure of the angle in congenital glaucoma and the "cleavage syndrome" of the anterior chamber.

Animals↗
PubMed1980

The tight junctions of rabbit choroid plexus and ciliary body epithelia. A comparative study using the double replica freeze-fracture technique.

The spatial arrangement of tight junctions in choroid plexus and ciliary body rabbit epithelia has been determined by studying freeze-fracture complementary replicas. In the choroid plexus epithelium, the interruptions of the junctional P-face fibrils were measured to be 14% in their total length. In the ciliary body epithelium, where the fibrils were found to be more fragmented than in the choroid plexus, the P-face fibril interruption accounted for 12% of the total length of the zonulae occludentes sealing the non-pigmented cells and 30% in the focal linear tight junctions connecting the non-pigmented cells at their apices. In both epithelia, the interruptions of the ridges are precisely complemented by particles or short bars of similar length found in the E-face furrows. Consequently, it is possible to conclude that the junctional fibrils are continuous in these two epithelia. For the zonulae occludentes, this continuity appears to be inconsistent with the 'leaky' properties of these epithelia shown by some physiological investigations.

Animals↗
PubMed1980

Analysis of cardiac kinetics: use of a new photo-optic technique.

The photokymograph (PKG) is a new noninvasive instrument that can record segmental myocardial wall motion from self-illuminated images such as are produce; by fluoroscopy, cine ventriculography, two-dimensional sonography, and 99mTc scintigraphy. The PKG can be calibrated to provide amplitude of myocardial tissue motion. The recordings of segmental wall motion obtained closely resemble those recorded by established techniques, both during control state and during ischemic episodes. Regression analysis was performed to compare PKG recordings with frame by frame analysis of left ventriculograms (0.98) and with M-mode echo derived from two-dimensional images (r = 0.97). The PKG has some distinct advantages over existing techniques used to analyze segmental wall motion: it is inexpensive, usable simultaneously over multiple areas, analyzes individual beats, and is not restricted to any particular myocardial wall or any particular angle of motion.

Echocardiography↗
PubMed1980

Application of conditional probability analysis to the clinical diagnosis of coronary artery disease.

Analysis of multiple noninvasive tests offers the promise of more accurate diagnosis of coronary artery disease, but discordant test responses can occur frequently and, when observed, result in diagnostic uncertainty. Accordingly, 43 patients undergoing diagnostic coronary angiography were evaluated by noninvasive testing and the results subjected to analysis using Bayes' theorem of conditional probability. The procedures used included electrocardiographic stress testing for detection of exercise-induced ST segment depression, cardiokymographic stress testing for detection of exercise-induced precordial dyskinesis, myocardial perfusion scintigraphy for detection of exercise-induced relative regional hypoperfusion, and cardiac fluoroscopy for detection of coronary artery calcification. The probability for coronary artery disease was estimated by Bayes' theorem from each patient's age, sex, and symptom classification, and from the observed test responses. This analysis revealed a significant linear correlation between the predicted probability for coronary artery disease and the observed prevalence of angiographic disease over the entire range of probability from 0 to 100% (P less than 0.001 by linear regression). The 12 patients without angiographic disease had a mean posttest likelihood of only 7.0 +/- 2.6% despite the fact that 13 of the 60 historical and test responses were falsely "positive." In contrast, the mean posttest likelihood was 94.1 +/- 2.8% in the 31 patients with angiographic coronary artery disease, although 45 of the 155 historical and test responses were falsely "negative." In 8 of the 12 normal patients, the final posttest likelihood was under 10% and in 26 of the 31 coronary artery disease patients, it was over 90%. These estimates also correlated well with the pooled clinical judgment of five experienced cardiologists (P less than 0.001 by linear regression). The observed change in probability for disease for each of the 15 different test combinations correlated with their information content predicted according to Shannon's theorem (P less than 0.001 by linear regression). These results support the use of probability analysis in the clinical diagnosis of coronary artery disease and provide a formal basis for comparing the relative diagnostic effectiveness and cost-effectiveness of different test combinations.

Adult↗
PubMed1980

Primary and acquired forms of moyamoya syndrome. A review and three case reports.

Moyamoya is the name given to an angiographic picture consisting of bilateral intracranial carotid artery occlusion associated with telangiectatic vessels in the region of the basal ganglia. It appears that patients with this angiographic finding can be divided into two distinct clinical groups. The first consists of children with a "primary" form of moyamoya that causes alternating hemiplegia, frequently of nonprogressive nature. The second consists of children and adults with various underlying diseases who develop an "acquired," usually progressive form of moyamoya. The striking predominance of Japanese patients with primary moyamoya and its high familial occurrence suggests that the primary form represents a hereditary malformation of the cerebral vascular bed. We report three additional cases of moyamoya. One case represents the primary form and the two are examples of the acquired form in a child and an adult.

Arterial Occlusive Diseases↗
PubMed1980

[Phacoemulsification and corneal endothelium: experimental study by scanning microscopy (author's transl)].

The various traumatic lesions occurring in the corneal endothelium during phacoemulsification were studied in the eyes of anesthetized rabbits. A comparison was made between the effects of massive perfusion of the anterior chamber with simple isotonic saline or Earle's solution, ultrasound emission, total phacoemulsification, and classical extracapsular extraction. The endothelium was examined by electronic scanning microscopy to cover large areas of the endothelium. Simple perfusion with Earle's solution does not alter the appearance of the endothelium, though some modifications in apical digitations may be observed. Perfusion with isotonic saline solution for 15 minutes modifies the appearance of the endothelial surface, with early necrosis in several cells. Ultrasounds provoke complete necrosis of a few isolated cells but do not cause major changes in most of them. Phacoemulsification produces endothelial ulcerations, probably from the trauma from lens debris. Extracapsular extraction, difficult in the rabbit, is the cause of much larger lesions with cell necrosis and vast areas of ulceration.

Animals↗
PubMed1979

Subglottic mucocele in an infant.

A subglottic mucocele caused partial obstruction of the upper airways. The radiologic findings were asymmetrical narrowing of the subglottic area with a mass arising from its posterior wall simulating a subglottic hemangioma. Surgical treatment was successfull.

Glottis↗
PubMed1979

Photokymography: a noninvasive method of detecting ischemic segmental myocardial wall motion abnormalities.

The photokymograph is a new and simple noninvasive device for assessing epicardial segmental myocardial wall motion utilizing cardiac fluoroscopy and image intensification. The validity of this technique in detecting wall motion changes occurring with ischemia was assessed in seven closed chest dogs undergoing acute balloon occlusion of the left circumflex coronary artery. Acute occlusion resulted in a prompt change in the analog signal of the photokymogram, characterized first by a decreased systolic inward motion and late systolic outward movement that later became akinetic and dyskinetic. Systolic amplitude decreased 18 +/- 7 percent (mean +/- standard error of the mean) within 5 seconds of occlusion and progressed to systolic outward motion (- 106 +/- 24 percent) at 2 minutes. The time course and type of morphologic changes observed after occlusion were similar to those previously described using invasive methods. Furthermore, such changes preceded electrocardiographic S-T segment elevation. These data suggest that photokymography is a sensitive technique for noninvasive detection of acute ischemic segmental wall motion abnormalities and holds promise as a simple method of detecting ischemic heart disease in man.

Animals↗
PubMed1978

Ultrastructural study of the cornea in the chick embryo.

The study of the development of the cornea in the chick embryo by transmission and scanning electron microscopy allows us to observe the differences between the aspect of thin sections and the surface of the cells. When studied with the T.E.M. both endothelium and epithelium have a rather normal and mature aspects on the 9th day of development. Observed with the S.E.M., the aspect of the surface of the epithelium becomes mature no earlier than on the 19th day, whereas the development of the endothelium is completed only after hatching. The development of apical junctional complexes occurs at a later stage in the organisation of the endothelial layer.

Animals↗
PubMed1978

Endothelial cell junctions in the ciliary body microvasculature. A freeze-fracture study in the rabbit.

Endothelial cells of the microvasculature (arterioles, fenestrated capillaries, and small venules) of the rabbit ciliary body have been examined in freeze-fracture replicas in ultrahigh vacuum and at very low temperatures, with special regard to their junctional boundaries. The junctional complexes of fenestrated capillaries and venular endothelium are discontinuous and do not seal the interendothelial clefts. They cannot be compared with zonulae occludentes or tight junctions, while the junctions in the arteriolar endothelium are continuous and well organized, suggesting a very low degree of paracellular permeability. It would be of interest to know if these structural differences at the junctional level in each segment of the microvasculature correspond to different paracellular permeability properties.

Animals↗
PubMed1978

Hypopharyngeal injury as a result of attempted endotracheal intubation.

Perforation of the hypopharynx due to traumatic attempted endotracheal intubation usually occurs during resuscitation efforts under poor conditions, but may occur even under optimal conditions due to improper technique. The implication of the appearance of subcutaneous emphysema in the neck, cyanosis, or pneumothorax during or following attempts at endotracheal intubation should be known. Direct laryngoscopy may be helpful in establishing the injury but early radiological examination is necessary for diagnosis of the site and extent of the perforation. The radiological contribution appears to be decisive in the choice of treatment. The radiological findings and the considerable morbidity observed in 6 cases of hypopharyngeal injury are described.

Adult↗
PubMed1978

Corneal changes due to alkali burns.

Rabbit corneal epithelium and endothelium were destroyed in vivo with 0.5 normal sodium hydroxide applied to the anterior surface of the cornea for 1 minute. Specimens were studied by transmission and scanning electron microscopy. Cellular necrosis is intense during the first day and healing begins on the third day on both surfaces of the cornea. The epithelial side is covered with new cells in 12 days and the eptihelium is normal on the 21st day, but there is a transformation of part of the corneal epithelium by conjunctival epithelium. On the endothelial side, healing is very slow and for this there seems to be two reasons: (1) Persistent cellular necrosis, (2) Inflammatory reaction which disorganizes the regenerating process. The overstimulation caused by this slow cicatrization leads to the formation of a retrocorneal membrane similar to those observed in human pathology.

Animals↗