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Biomedical subjects

M Michejda

Publications and source records attributed to M Michejda.

At least 37 records · Page 2Linked to original sources
PubMed1984

Fetal hydrocephalus. II. Amelioration of fetal porencephaly by in utero therapy in nonhuman primates.

The postnatal course of a form of infantile porencephaly under pressure in monkeys was evaluated by comparing brain development between animals that had received the hydrocephalic antenatal vent for intrauterine treatment and those that had not been treated antenatally. Brain development was assessed by computed tomographic scans. The studies showed asymmetric malformations and associated porencephalic lesions in infant monkeys not treated in utero, despite installation of a conventional postnatal ventriculoperitoneal shunt. In contrast, apparently normal development of brain tissue in infants given intrauterine therapy was observed.

Amnion↗
PubMed1984

Intrauterine treatment of spina bifida: primate model.

A spina-bifida-like condition was induced in 8 Macaca mulatta fetuses by intra-uterine lumbar laminectomy (L3-L5) followed by displacement of the spinal cord from the central canal. This condition was repaired in utero in 5 animals. A key feature of the repaired in utero in 5 animals. A key feature of the repair method was the use of allogeneic bone paste made from fetal bone particles suspended in an agar-thickened modified Dulbecco's medium. The bone paste was used to correct the bone deficit produced by the laminectomy. All of the monkey babies were delivered by cesarean section at near term (160-164 days of gestation). Neurological test on the neonates and subsequent morphological studies indicated that the in utero treated animals developed normally. In contrast, 3 control animals, which had the induced spinal dysraphism but were left untreated, showed severe spina-bifida-like abnormalities, including paraplegia, incontinence and somatosensory loss.

Animals↗
PubMed1982

Fetal treatment 1982.

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Congenital Abnormalities↗
PubMed1981

In utero diagnosis and treatment of non-human primate fetal skeletal anomalies. I. Hydrocephalus.

We describe the antenatal diagnosis and intrauterine treatment of hydrocephalus induced (corticosteroid teratism) in fetal rhesus monkeys. Diagnostic techniques included (1) maternal serum alpha-fetoprotein (AFP) measurement, (2) ultrasonography of the fetal ventricular system, (3) roentgenography, and (4) fetoscopy. After measuring excessive intracranial CSF pressures in hydrocephalic fetuses, an indwelling prosthetic valve was devised--the hydrocephalic antenatal vent for intrauterine treatment (HAVIT). The HAVIT was surgically implanted in the fetal skull so that when CSF pressures exceeded 60 mm H2O, the ports opened to vent CSF from the fetal ventricular system into the amniotic fluid. Whereas unaided hydrocephalic neonates seldom survived more than ten to 14 days, manifesting progressive muscular weakness and frequent seizures, fetal monkeys receiving the HAVIT demonstrated markedly superior postnatal development of motor skills and weight gain. Although additional laboratory studies are indicated, ultimately, clinical investigations combining early diagnosis and in utero insertion of the HAVIT or similar prosthesis may significantly enhance the prognosis of children in whom severe antenatal hydrocephalus develops.

Animals↗
PubMed1981

In utero allogeneic bone transplantation in primates: roentgenographic and histological observations.

Intrauterine allogeneic bone transplantation was performed on 25 monkey fetuses at 120 to 135 days of gestation. Two surgical techniques for orthotopic transplantation of the humeral midshaft were utilized: (1) A segment (5 to 7 mm) of fetal humerus was transplanted from fetus (donor) to fetus (recipient). An intramedullary pin (Kirschner orthopedic wire) was used for fixation of the severed humerus. (2) Without severing the humerus, a midshaft area (5 to 7 mm X 5 to 6 mm) was surgically ablated. A bone paste composed of crushed bone particles mixed with an agar-enriched culture medium was sculpted to fill this lesion. We used fresh frozen or fresh allograft tissue with equal success. Postsurgical observations included serial roentgenographic and histological evaluation of humeral osteogenesis, as well as postnatal assessment of limb use. The contralateral arm served as a control. Our findings indicate that the immune surveillance system of fetal monkeys may be tolerant of these bone allografts; alternatively, healing by substitution may also occur. The roentgenographic and histological results demonstrate that both of the transplantation procedures used here achieved restoration of the long bone. The use of bone paste allowed us to sculpt the allograft to the desired conformation. These results from laboratory primate models encourage continued investigation of fetal allogeneic bone transplantation, because of its ultimate potential for intrauterine repair of skeletal anomalies in man.

Animals↗
PubMed1980

Surgical approaches in fetal radiography and the study of skeletal age in Macaca mulatta.

The fetal surgery and fetal radiography utilized in longitudinal radiographic study of bone maturation in Macaca mulatta and their implications for fetal surgery are discussed. The novel technique of serial uterotomies and multiple exposure of the same fetus (two-week intervals) starting on 120 days of gestation as well as anesthesia and surgical procedures are presented.

Abortion, Veterinary↗
PubMed1980

Growth standards in the skeletal age of rhesus monkey (M. mulatta) chimpanzee (Pan tryglodytes) and man.

Various methods of age assessment in nonhuman primates of unknown gestation or chronological age are discussed. The most precise of all methods, the utilization of skeletal age (appendicular bone maturation), is described. The prenatal growth standards and age indicators of M. mulatta are discussed and compared to Pan tryglodytes and man. Also several post-natal growth standards comparable in M. mulatta, Pan tryglodytes and man are presented. The determination of unknown age of experimental animals which provide an accurate basis of comparison with human material is discussed.

Adolescent↗
PubMed1979

Estimation of gestational and skeletal age in Macaca mulatta.

Results of qualitative and quantitative studies of prenatal skeletal development in Macaca mulatta are presented. Longitudinal radiographic observations were carried out on 20 monkeys of known gestational age, beginning on 120 days of gestation until the neonatal stage of skeletal development. These studies were based on multiple uterotomies on each pregnant female. The technique described provides accurate data on prenatal bone ossification, and permits an accurate estimation of fetal age in pregnant rhesus monkeys with unknown conception dates.

Age Determination by Skeleton↗
PubMed1975

Ontogenic growth changes of the skull base in four genera of nonhuman primates.

Cross-sectional studies of the degree of the cranial base flexion were carried out in infant, juvenile and adult skulls in four genera of nonhuman primates (P. paniscus, H. lar, P. urinus, and M. mullatta). The cephalometric observations of the cranial base included linear and angular measurements of each specimen. The data obtained in this study showed that the anterior portion of the cranial base exhibits a significant shortening trend as the mammalian evolutionary scale ascends. Moreover, the growth pattern of the anterior portion of the skull base follows that of the facial bony structures. The ontogenic growth changes of the posterior portion of the skull base follows the growth pattern of the endocranial cavity. The significant trend of elongation in this area directly contributes to the posterior migration of the foramen magnum. The magnitude of these growth changes decreases as the evolutionary scale ascends. The angular measurements of the cranial flexion showed a less obtuse cranial base angle in young specimens and the ones higher on the mammalian scale. The skull kyphosis was less pronounced in these specimens and the anatomical features of the cranial base were more humanlike, including the balance of the head expressed by the position of the foramen magnum.

Age Factors↗