PubMed Health⌕ Search

Biomedical subjects

J Lind

Publications and source records attributed to J Lind.

16 recordsLinked to original sources
PubMed1979

Bovine serum chitinase.

1. A glycol-chitin-splitting enzyme without lysozyme (muramidase) activity has been found in calf serum. The enzyme also degrades colloidal chitin and is thus a true chitinase, 1,4-beta-poly-N-acetylglucosaminidase, without exo-beta-N-acetylglucosaminidase effect. 2. The enzyme is purified 1000-fold by ion-exchange chromatography and gel filtration. Its optimal activity is between pH 1.5-2.0 with glycol chitin and between pH 3-6 in a rather broad optimum with colloidal chitin as substrate. The optimal stability of the enzyme is in the pH interval 3.0-6.5 when tested by incubation with glycol chitin at 50 degrees C for 60 min. The optimal temperature for the degradation of glycol chitin is 40 degrees C when assayed at pH 1.5 and 51 degrees C when assayed at pH 3.5. 3. The enzyme is activated by moderate heating at pH 6.5. The highest relative activity, 135% is reached after 45 min incubation at 30 degrees C, pH 5 or after 30 min at 40, pH 2.4. By incubation with small amounts of trypsin at pH 6.5 at 3m degrees C the enzyme was temporarily activated. 4. The isoelectric point, pH 5.3, and the molecular weight, 47,000 +/- 3,000 were determined by respectively isoelectric focusing and gel filtration. 5. The Michaelis-Menten constant, Km = 0.76 +/- 0.05 (S.E.) mg/ml, was measured with glycol chitin as substrate.

Animals↗
PubMed1978

Structure and closure mechanism of the human umbilical artery.

The structure of the fully-patent umbical artery and rearrangement of its structural elements with postnatal closure were examined 10 centimeter long umbilical cord segments which were double-clamped at different time intervals after delivery. The fully-patent umbilical artery consists of two main layers: an outer layer of circularly arrange smooth muscle cells and an inner layer which shows rather irregularly and loosely arranged cells embedded in abundant metachromatic ground substance. No predominantly longitudinal arrangements of cells and fibers reported by earlier investigators could be identified in the inner layer. Closure of the umbilical arteries is initiated by numerous localized contractions which are mainly formed by muscle cells of the outer circular layer. Ultimate closure of larger segments of the umbilical arteries is also mainly produced by contractions of the outer layer. In contrast, the inner layer (which is rich in ground substance) seems to serve mainly as a plastic tissue which can easily be shifted in an axial direction and then folded into the narrowing lumen to complete closure. Electron microscopy reveals that the cells of this layer represent rather poorly differentiated smooth muscle cells which contain only a few tiny myofilaments and can therefore hardly contribute actively to the process of closure.

Cell Differentiation↗
PubMed1977

Closure of the human umbilical artery: a physiological demonstration of Burton's theory.

30 umbilical cords of normal full-term infants were examined immediately after birth for closure of the arteries. Multiple constrictions were observed in the arteries at birth, which increased in number and degree with time. Between the constrictions there were segments of dilatations with trapped blood. Cutting through the constrictions in the cords clamped later than 1 min after birth did not result in leakage of blood from the adjoining dilated segments which contained trapped uncoagulated blood indicating complete closure. This behavior of the vessels is a physiologic example of critical closure of small arteries according to Burton's theory.

Humans↗
PubMed1977

Effect of early and late cord clamping on the systolic time intervals of the newborn infant.

The effect of early and late cord clamping on the left ventricular performance of the newborn infant was assessed by measuring the systolic time intervals from the indirect carotid pulse tracings and simultaneous phonocardiogram and electrocardiogram. The study was performed in 13 normal, full-term infants sequentially at 20-105 min, 6-6 1/2 hrs, and 24-27 hrs of age. The umbilical cords were clamped early in 7 (E.C.) and clamped late in 6 infants (L.C.). The ratio of the pre-ejection period (PEP) to the left ventricular ejection time (LVET) was found to be significantly higher in the L.C. infants (mean +/- S.E., 0.400 +/- 0.18, 0.433 +/- 0.018, 0.410 +/- 0.021) compared with those of the E.C. (0.334 +/- 0.010, 0.347 +/- 0.009, 0.361 +/- 0.007) with p values of less than 0.01, less than 0.005 and less than 0.05, respectively in the three examination periods. The higher PEP/LVET ratios in the L.C. infants were mainly attributable to a prolongation of the PEP. It is suggested that late cord clamping, by allowing a sizable placental transfusion, appeared to affect adversely the left ventricular performance of the neonate. Furthermore, it is suggested that in evaluating systolic time intervals of the neonate during the first days of life, the volumic state or status of placental transfusion should be taken into consideration as a determinant.

Female↗
PubMed1977

Eleventh Edgar Mannheimer Lecture. Human fetal and neonatal circulation. Some structural and functional aspects.

Normally the neonatal circulation adjusts itself gradually during the first days of extrauterine life. The different closure rates of the major fetal vascular channels (umbilical vessels, ductus venosus, ductus arteriosus, and foramen ovale) permits smooth alterations in direction and size of shunts, should the balance of vascular resistance and pressure become upset. The study of the influence of placental transfusion on the cardio-respiratory adaptation has again demonstrated the great capacity of the transitional circulation to cope with all the strains involved in the reorganization of the circulatory system at birth. Such a capacity proves the existence of an effective system of integrated baroreceptor--and chemoreceptor--reflexes (peripheral and central).

Animals↗
PubMed1976

Chitinase and beta-N-acetylglycosaminidase in the digestive juice of Helix pomatia.

A beta-N-acetylglucosaminidase from Helix pomatia digestive juice was separated and partly purified by gel chromatography. The optimal pH for the degradation of p-nitrophenyl-N-acetyl-beta-D-glucosaminide was 3.4. The molecular weight was around 160 000 and the pI = 4.95. In the same gel chromatography run two chitinase active peaks were also obtained. These chitinase active peaks were also obtained. These chitinases, with molecular weights around 26 000 and 13 000, had somewhat different pH activity curves with optima at 4.2 and 4.3. By isoelectric focusing the first peak with molecular weight around 26 000 was divided in two chitinase active regions with pI at 5.7 and 3.5. The second peak with molecular weight around 13 000 had a pI at 7.3.

Acetylglucosaminidase↗
PubMed1975

[Family birth].

Explore the source record for details and available documents.

Family Planning Services↗
PubMed1975

Lincomycin in selective medium for the isolation of Neisseria gonorrhoeae.

For the isolation of gonococci, the selective culture medium containing colistin, vancomycin, nystatin and trimethoprim which is usually employed has been changed by substituting lincomycin for vancomycin. The best result was obtained if a concentration of 1/2 mug lincomycin/ml medium was used. This is a concentration of lincomycin considerably lower than that which by other investigators is considered most suitable for the purpose. However, the culture medium used by the latter did not contain trimethoprim. The use of 1/2 mug lincomycin/ml instead of vancomycin 3 mug/ml in the medium caused a slightly more pronounced growth of unwanted organisms. In spite of this, the results obtained by the medium containing lincomycin showed that the number of samples positive for gonococci was 7 per cent higher, and that the number of patients with gonococcal infections to be discovered was 4 per cent higher than the numbers obtained by the medium containing vancomycin. The results were considered highly favourable and, accordingly, by now our laboratory uses 1/2 mug lincomycin/ml medium in the routine isolation of gonococci.

Culture Media↗