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Biomedical subjects

R M Klein

Publications and source records attributed to R M Klein.

At least 163 records · Page 9Linked to original sources
PubMed1981

The effects of dipalmitoyl phosphatidyl choline on the precipitation of native fibrils and segment-long-spacing aggregates from collagen solution.

The effect of dipalmitoyl phosphatidyl choline (DPPC), the major phospholipid component of pulmonary surfactant, on the precipitation of collagen in the form of native fibrils and segment-long-spacing (SLS) aggregates was studied in vitro. The effects of DPPC on both phases of collagen fibrillogenesis were analyzed spectrophotometrically, and alterations in the morphology of precipitated fibrils and SLS aggregates were ascertained by transmission electron microscopy (TEM). Low concentrations of DPPC inhibited the growth phase of fibrillogenesis, while higher concentrations were required to inhibit nucleation. Both the meshwork density and mean width of precipitated fibrils were altered by DPPC, as was the size of SLS aggregates. Segment-long-spacing aggregates prepared from pepsin-treated collagen were inhibited to a greater degree than SLS aggregates prepared from untreated collagen, indicating that the pepsin-susceptible residues of the telopeptide extensions of tropocollagen molecules stabilize SLS aggregates against the effects of DPPC. Based on these results and the inhibition of the growth phase at lower concentrations than those which inhibited the nucleation phase of fibrillogenesis, it was concluded that the primary mechanism of DPPC inhibition is electrostatic interference between the positively charged phospholipid molecules and the net positive charge of collagen. It is proposed that pathological conditions involving the pulmonary epithelium may allow interaction between surfactant and collagen, which could further weaken the interstitial connective tissue.

Animals↗
PubMed1981

Autoradiographic assessment of 3H-proline uptake by osteoblasts following guanethidine-induced sympathectomy in the rat.

Sympathectomy was carried out in rats by injections of guanethidine-sulfate from birth to 14 days of age. At 45 days of age, the activity of osteoblastic cells was monitored by 3H-proline autoradiography. Effectiveness of sympathectomy was verified by light-microscopic examination of superior cervical and celiac ganglia. Grain counts over periosteal osteoblasts of the femoral diaphysis and osteoblasts mesial to the first molar in the mandible demonstrated a significant reduced uptake of 3H-proline in the sympathectomized rats. The data provide direct evidence of sympathetic influence on osteoblastic activity and suggest that sympathectomy may result in the loss of a trophic influence which is important in the regulation of osteogenesis.

Animals↗
PubMed1981

Pressure relief training device: the microcalculator.

The use of a commercially available timer/microcalculator as a pressure relief training device for spinal cord injury patients is discussed. The device can be programmed to emit a high frequency tone at the end of a specified time interval, and then reset itself to repeat the cycle as long as is desired. The device's low cost, high reliability, convenient size and attractiveness to patients contribute to high potential as a training device. A rationale for using such a device soon after the onset of disability, rather than after pressure sores develop, is discussed.

Equipment and Supplies↗
PubMed1980

The value of routine preoperative chest roentgenograms in infants and children.

The charts and routine preoperative roentgenograms of 350 children admitted for elective pediatric surgery were analyzed to evaluate the clinical importance of routine preoperative chest roentgenograms. This analysis, and a review of the literature, should indicate that routine preoperative roentgenograms for elective pediatric surgery are unnecessary. Indications for selected preoperative roentgenograms based on patients' history and clinical findings are enumerated.

Adolescent↗
PubMed1980

Pattern of crypt cell proliferation in the pre- and post-closure ileum of the neonatal rat: effects of sympathectomy.

The present experiments were designed to investigate ileal crypt cell division before and after neonatal closure to macromolecular absorption by measurements of mitotic index, labelling index, colchicine-induced estimation of mitotic rate (mitoses/cell/hour) and crypt depth and villus height on postnatal days 15--23. In addition, the effects of the sympathetic nervous system on crypt cell proliferation were analyzed by guanethidine-induced sympathectomy. Guanethidine treatment resulted in at least a 70% reduction in superior cervical and coeliac perikarya at 15 days after birth. All cell proliferative indices demonstrated a rather constant rate of cell division in the ileal epithelium between 15 and 17 days after birth with a sudden burst of mitotic activity on day 18. The mitotic rate of control rats increased from day 18 to 23 with 3-week-old rat demonstrating a faster rate of ileal crypt cell proliferation than adult rats. The ileal crypt depth more than doubled between 15 and 23 days while the height of the villus column increased slowly but steadily (36%) during the period of this study. Cell division is inhibited by guanethidine-induced sympathectomy although there is still an acceleration of mitosis in the post-closure period. The relationship of sympathectomy and ileal crypt cell proliferation is discussed and compared to hormonal effects on closure and related developmental events.

Animals↗
PubMed1980

Cell cycle kinetics of uninfected and feline leukemia virus-infected canine lymphoma cell lines: effects of methotrexate treatment.

The cell cycle kinetics of uninfected and feline leukemia virus-infected canine lymphoma cell lines were determined by autoradiography (PLM method) as follows: DT-5: generation time (TC), 15.2 h; pre-synthetic gap phase (TG1), 3.2 h; DNA-synthetic phase (TS), 8.2 h; post-synthetic gap ph se (TG2), 3.3 h; visible mitotic phase (TM), 0.5 h. 11028: TC, 13.6 h; TG1, 1.9 h; TS, 7.7 h; TG2, 3.4 h; TM, 0.6 h. 11028+FeLV (11028 productively infected with feline leukemia virus): TC, 11.2 h; TG1, 0.2 h; TS, 8.3 h; TG2, 2.1 h; TM, 0.6 h. Exposure of the lymphoma cell lines to methotrexate (MTX) in vitro produces dose-related increases in cellular volume, associated with reductions in cellular proliferation. The relative sensitivities of these cell lines to MTX, measured by the ID50 MTX concentrations for DT-5, 11028, and 11028+FeLV are 118 nM, 122 nM, and 28 nM respectively. The cell kinetic effects of the ID50 MTX concentrations added to cultures of lymphoma cells pulse-labeled with tritiated thymidine are an approximately 2-h prolongation of TC, attributable to a lengthening of TS, with other cell cycle phases not significantly altered. These cell lines are highly tumorigenic when transplanted into the cheek pouches of immunosuppressed hamsters, with inocula of 10(4) cells producing rapidly growing, well vascularized tumors.

Animals↗
PubMed1980

Circadian rhythms in neonatal rat parotid gland acinar cell and ileal crypt cell mitosis.

Mitotic activity of parotid gland acinar cells and ileal crypt cells was analyzed over the course of a 26-hour period at 8 and 15 days after birth. At 8 days there is no detectable circadian rhythm of mitosis in either tissue while at 15 days after birth there is a mitotic rhythm with an amplitude of 36.8% in ileum and 26.5% in parotid gland. Possible factors which may influence and initiate circadian rhythms are discussed.

Aging↗
PubMed1979

Greig cephalopolysyndactyly syndrome.

Based on the family presented and five others previously described, it can be concluded that the Grieg cephalopolysyndactyly syndrome is a fully penetrant autosomal dominant disease consisting of four variably expressed malformations: postaxial polydactyly (type B), preaxial polydactyly, syndactyly, and minor craniofacial abnormalities. This entity can be differentiated from other craniofacial-digital syndromes because of the absence of mental retardation, craniosynostosis, and brachydactyly.

Adult↗
PubMed1979

The effect of indomethacin pretreatment on aphakic cystoid macular edema.

In patients treated with oral indomethacin for four weeks after intracapsular cataract extraction, five of 57 eyes (9%) had cystoid macular edema four to six weeks postoperatively as shown by fluorescein angiography. In a control group not treated with indomethacin, 15 of 34 eyes (44%) had cystoid mascular edema. Oral indomethacin, therefore, caused a statistically significant decrease in the incidence of aphakic cystoid macular edema.

Adult↗
PubMed1979

The MURCS association: Müllerian duct aplasia, renal aplasia, and cervicothoracic somite dysplasia.

Two patients and 28 others in the literature were ascertained because of congenital vaginal agenesis associated with clinical and/or radiographic evidence of malformations derived from the cervicothoracic somites. In these patients, there was a high incidence of Müllerian duct aplasia/hypoplasia (96%), renal agenesis and/or ectopy (80%), and abnormalities related to cervicothoracic somite dysplasia, particularly 2 to 4 anomalous vertebrae located between C5-T1 (80%). These consistent findings suggest a distinctive non-random association of malformations: Müllerian duct (MU) aplasia, renal (R) aplasia, and cervicothoracic somite (CS) dysplasia (MURCS). Identification of one component of the MURCS association suggests the presence of the other associated anomalies. A hypothesis for the embryogenic pathogenesis of the MURCS association is proposed which attributes the malformations to an alteration of the blastemas of the lower cervical-upper thoracic somites, arm buds, and pronephric ducts, all of which have an intimate spatial relationship at the end of the fourth week of fetal life. A presently unidentified teratogen may be one of the possible causes of the MURCS association on the basis of a lack of familial transmission, normal chromosomal studies, and the similar effects of a known teratogen (thalidomide) on the developing genitourinary tract.

Abnormalities, Multiple↗
PubMed1979

Reversible effects of green and orange-red radiation on plant cell elongation.

The differential cell elongation of cress (Lepidium sativum) roots that results in geotropic bending can be decreased by green radiation with an action spectrum peaking at 550 nm. This decrease can be negated by prior or simultaneous irradiation by orange-red light with an action spectrum peaking at 620 nm. The green radiation appears to be effective during the cell elongation phase of geotropic response.

Journal Article↗