Three distinct molecular species of proteoglycan synthesized by the rat limb bud at the prechondrogenic stage

To characterize proteoglycans in the prechondrogenic limb bud, proteoglycans were extracted with 4 M guanidine HCl containing a detergent and protease inhibitors from Day 13 fetal rat limb buds which had been labeled with [35S]sulfate for 3 h in vitro. About 90% of 35S-labeled proteoglycans was solubilized under the conditions used. The proteoglycan preparation was separated by DEAE-Sephacel column chromatography into three peaks; peak I eluted at 0.45 M NaCl concentration, peak II at 0.52 M, and peak III at 1.4 M. Peaks I and III were identified as proteoglycans bearing heparan sulfate side chains. The heparan sulfate proteoglycan in peak III was larger in hydrodynamic size than the proteoglycan in peak I. The heparan sulfate side chains of peak III proteoglycan were smaller in the size and more abundant in N-sulfated glucosamine than those of peak I proteoglycan. Peak II contained a chondroitin sulfate proteoglycan with a core protein of a doublet of Mr 550,000 and 500,000. The chondroitin sulfate proteoglycan was easily solubilized with a physiological salt solution and the heparan sulfate proteoglycan in peak I was partially solubilized with the physiological salt solution. The remainder of the proteoglycan in peak I and the heparan sulfate proteoglycan in peak III could be solubilized effectively only with a solution containing a detergent, such as nonanoyl-N-methylglucamide. This observation indicates the difference in the localization among these three proteoglycans in the developing rat limb bud.

New assessment of airway responsiveness. Effect of pretreatment with procaterol on allergen-induced bronchoconstriction

We examined airway responsiveness to allergen inhalation using a novel technique by which dynamic compliance (Cdyn) and pulmonary resistance (Rl) are simultaneously calculated by Fourier-series analysis of flow and transpulmonary pressure during tidal breathing. C0 and C0.5 (Cdyn at the frequency of zero and 0.5 Hz, respectively) were computed using the regression line of Cdyn versus frequency measured at the fundamental and first three harmonics in each breathing cycle. First, the validity of this system was tested by comparing Rl, C0 and C0.5 during five consecutive breaths with those obtained by the conventional method. A good correlation was seen in Rl, C0 and C0.5 between the two methods. Second, we studied airway response to allergen inhalation before and after oral administration of a long-acting beta 2-stimulant (procaterol, 50 micrograms or 100 micrograms) or placebo in a double-blind crossover trial in six atopic asthmatic subjects. In control allergen inhalation tests by administration of placebo, Rl increased progressively, and C0.5, expressed as percentage of control compliance at zero frequency (C0.5/COcont), decreased progressively. After 100 micrograms procaterol, Rl response to allergen was almost completely inhibited. However, a decrease in C0.5/C0cont was still observed. These findings suggest that pretreatment of asthmatic patients with procaterol can release allergen-induced bronchoconstriction of the central airways, but cannot release that of the peripheral airways.

Studies on prolactin and growth hormone gene expression in the pituitary gland of spontaneous dwarf rats

The spontaneous dwarf rat (SDR) is a newly established experimental model for pituitary dwarfism with an autosomal recessive mode of inheritance. GH and PRL gene expressions were studied in the pituitary gland of this animal. Immunocytochemistry failed to detect any immunoreactive GH cells in SDR pituitary gland, whereas numerous PRL cells were encountered throughout the anterior lobe. Similarly, GH was not detectable in the pituitary cytosol from SDR of 7, 20, and 80 days of age. PRL of the same mol wt as the authentic rat PRL was found in the pituitary glands in all SDRs examined. Since these results were thought to be due to the absence of GH mRNA in the SDR's pituitary gland, we attempted to detect GH mRNA by dot hybridization. Very small amounts of GH mRNA were found in the pituitary glands of both male (2.6% of normal) and female (6.0% of normal) SDRs. Reduced levels of PRL mRNA were also found in the pituitary glands of male (50%) and female (30%) SDRs. Northern blot analyses of total RNA extracts revealed that the GH mRNA of the SDR was similar in size to the mature GH mRNA found in the pituitary glands of control rats. PRL mRNA from the SDR also migrated to the same position as normal PRL mRNA. Nuclear DNA preparations were prepared from normal and SDR livers, and the genomic organizations of the GH and PRL genes were examined using restriction mapping. The DNA fragment length patterns obtained with the cDNA probes for GH or PRL using several restriction enzyme digestions were identical. The results suggest that the GH deficiency in SDR is not due to a gross deletion or rearrangement of the GH gene. It is proposed that SDR may be an excellent experimental model for the study of isolated GH deficiency in the human.

Elevated accumulation of hyaluronate in the tubular bones of osteogenesis imperfecta

The content and composition of glycosaminoglycans in the tubular bones of osteogenesis imperfecta were compared to those in the tubular bones of age-matched controls. Chondroitin sulfate was the major glycosaminoglycan (70-80% of total) both in the normal and pathological bones, and its level, based on the tissue wet weight, was slightly less in the pathological bones. The composition of chondroitin sulfate disaccharide units in the pathological samples was different from those of the control; a lower proportion of chondroitin 4-sulfate unit. Hyaluronate accounted for at most 7% of total glycosaminoglycans from the normal bones. The hyaluronate content of the pathological bones was 1.5- to 3-fold higher than that of the controls. Glycosaminoglycans have been shown to participate in the formation of a functional supramolecular complex in extracellular matrices. Therefore, it may be postulated that the abnormalities in glycosaminoglycan composition in the tubular bones of osteogenesis imperfecta is implicated in some clinical aspects of this connective tissue disorder such as the bony fragility.

Studies on the development of growth hormone and prolactin cells in the rat pituitary gland by in situ hybridization

Cytogenesis of growth hormone and prolactin cells in the rat pituitary gland was studied using in situ cDNA-mRNA hybridization and immunocytochemistry. Frozen or Paraplast sections of fetal and neonatal pituitaries were hybridized with 3H-cDNAs for rat prolactin or growth hormone, and were then processed for autoradiography. A number of growth hormone mRNA-positive cells were encountered throughout the anterior lobe on day 19 of gestation. Individual variation in growth hormone gene expression was observed between fetuses at day 19 of gestation (6 out of 8 fetuses examined were positive for growth hormone mRNA). In contrast, growth hormone mRNA was detected in the all fetuses examined on day 20 or later. The autoradiographic signal (number of reduced silver grains) appeared to increase with later stages of development. Fetal growth hormone mRNA-positive cells were evenly scattered throughout the anterior lobe. Most of them were isolated, however, small clusters of several growth hormone cells were infrequently observed. Prolactin mRNA-positive cells were found first on the 22nd day (the last day of gestation) in 3 of 6 fetuses examined, but were rarely observed on earlier gestational days. By postnatal day 8, prolactin mRNA-positive cells were numerous and the grain density over prolactin cells increased. Both growth hormone and prolactin cells were found as early as 18 days of gestation using immunocytochemistry, although the number of positive cells was very small at this stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Defective association between collagen fibrils and proteoglycans in fragile bone of osteogenesis imperfecta

The relationship between collagen fibrils and proteoglycans in the bone matrices of three osteogenesis imperfecta (OI) patients was observed ultrastructurally to clarify the mechanism responsible for pronounced bony fragility. Collagen fibrils and noncollagenous components were prepared from the bone matrix of patients with osteogenesis imperfecta and a control sample, respectively. Compared with the control, a 95.2% decrease was found in the number of proteoglycan granules periodically associated with the cross-banding of collagen fibrils in one OI sample from a patient with severe bony fragility. Extractability of collagen fibrils and proteoglycans was high in this sample. However, proteoglycans and collagen fibrils could be reattached in vitro to reproduce the condition observed in the controls. There was no decrease in the number of proteoglycan granules attached to prepared collagen fibrils in a sample from a patient with predominantly bowing deformity of bones. Hypothetically, the separation of proteoglycans from collagen fibrils in OI may be associated with increased bony fragility. In osteogenesis imperfecta patients, the mechanism inducing bowing deformity appears to be different from that inducing fragility.

Possible site of bronchodilation due to inhaled procaterol aerosol in asthmatic patients

We studied the effective site of an inhaled aerosol of procaterol, a beta 2-selective adrenergic bronchodilator, in 8 asthmatic patients whose basal lung functions are almost within the normal range in both slow vital capacity (VC) and forced expiratory volume in one second (FEV1.0), and are free from asthmatic attack. In patients who had received procaterol 30 min after inhalation of aerosol, there was no significant change in VC, although FEV1.0, maximal expiratory flow at 50% VC (V50), maximal expiratory flow at 25% VC (V25) and maximal expiratory flow at 30% VC of partial maximal expiratory flow volume curve (V30p) improved significantly. On the other hand, in those who had received placebo, none of the parameters changed. Furthermore, R1 decreased and C0.5 increased significantly during the first 5 min after inhalation of procaterol aerosol. After an interval of 5 min, R1 did not change any further, while C0.5 continued to improve until 30 min after inhalation of procaterol. These results suggest that procaterol may first dilate the large airway and then may gradually dilate the small airway in bronchial asthma.

A new method of inhalation challenge with propranolol: comparison with methacholine-induced bronchoconstriction and role of vagal nerve activity

To establish a safe procedure for examining propranolol-induced bronchoconstriction, we have developed a new method for performing inhalation challenge with propranolol. Monitoring respiratory resistance during tidal breathing with continuous inhalation of propranolol in 1.5-fold increasing concentrations from 0.78 to 30 mg/ml for 1 minute at each concentration, we tested 43 subjects with stable asthma and 10 normal subjects. We also compared bronchial responsiveness with responsiveness to inhaled methacholine on separate days. In addition, to determine the role of vagal nerve activity in propranolol-induced bronchoconstriction, we studied the effect of atropine. Inhaled propranolol caused dose-related bronchoconstriction in all subjects with asthma but not in normal subjects. None of the subjects suffered severe asthmatic attack during the test, which was performed in 15 minutes or less. The minimum cumulative dose of methacholine and of propranolol, at the point where respiratory conductance began to decrease, was not significantly correlated. Increased respiratory resistance was reversed by atropine in 70% of the subjects with asthma with marked individual differences. These data suggest that, although in most subjects with asthma, vagal nerve activity contributes in varying degree to bronchoconstriction, other constricting factors may contribute in the remaining subjects. It is also suggested that the mechanism of bronchial response to propranolol differs from that of the nonspecific airway reactivity estimated by methacholine challenge.

Possible sensory receptor of nonadrenergic inhibitory nervous system

To determine the sensory receptor of the nonadrenergic inhibitory nervous system (NAIS), 22 cats were anesthetized and serotonin was continuously administered (50-250 micrograms.kg-1.min-1 iv) to increase pulmonary resistance (RL) to 377 +/- 57% (SE) of the control value. We then 1) mechanically irritated the trachea, 2) intravenously administered capsaicin (5 micrograms/kg), or 3) induced hypoxia (arterial PO2 30-40 Torr) to stimulate irritant and bronchial C-fiber receptors, pulmonary C-fiber receptors, or the carotid body (chemoreceptors), respectively. After treatment with atropine (3 mg/kg iv) and propranolol (2 mg/kg iv), the serotonin-induced change in RL was reduced by 58.6 +/- 14.3% by mechanical irritation and 63.3 +/- 12.1% by intravenous capsaicin. However, hypoxia produced no dilatation of the airways. In further experiments, we employed capsaicin inhalation to stimulate bronchial C-fiber receptors. Inhaled capsaicin (0.1%, for 5 breaths) also reduced RL by 79.2 +/- 9.2% of the elevated value, after atropine and propranolol. Treatment with a ganglionic blocking agent, hexamethonium (2 mg/kg iv), abolished bronchodilator responses, implying that a reflex pathway through vagal nerves is involved in this phenomenon. These results suggest that pulmonary and bronchial C-fiber receptors may be involved as sensory receptors in NAIS reflex bronchodilatation.

Levels of creatine kinase activity in cartilage of tubular and nontubular bone in relation to pathogenesis of achondroplasia

For the purpose of investigating events of energy metabolism in growing cartilages of human tubular and nontubular bones, measurements of creatine kinase (CK), lactate dehydrogenase (LDH), and aldolase of freshly excised cartilages in normal and pathologic conditions were performed. The level of cartilage CK of the normal phalanges (tubular bone) and exostosis was significantly less than those of the normal iliac bones (nontubular bone) and the achondroplasia tubular bone. A similar difference was also found between the tubular and the nontubular bone of an autopsy subject with achondroplasia. There was no statistical difference in the levels of LDH and aldolase in the cartilage between the tubular and the nontubular bone. These observations together with results obtained from iliac and limb cartilages of the newborn rat suggest the hypothesis that CK activity of cartilage of the tubular and the nontubular bone is different; cartilage of achondroplasia tubular bone has CK activity similar to that of normal nontubular bone cartilage.

Uptake and retention of 3H-estradiol by gonadotrophs and lactotrophs in the pituitary glands of the guinea pig, hamster and gerbil

Nuclear uptake and retention of 3H-estradiol by luteinizing hormone (LH) and prolactin (PRL) cells was examined in three species of rodents (guinea pigs, hamsters and gerbils) using the combined techniques of immunocytochemistry and autoradiography. Castrated animals were injected with 3H-estradiol and decapitated 1.5 h later. The pituitary glands were processed for thaw-mount autoradiography followed by conventional immunocytochemical staining for LH and PRL. 3H-estradiol accumulated in more than 80% of the anterior pituitary cells in the gerbils, while only 33 and 22% of the cells accumulated 3H-estradiol in the hamsters and guinea pigs, respectively. A varying percentage of immunoreactive LH and PRL cells in all three species were found also to contain binding sites for estradiol. Some LH and PRL cells in hamsters and guinea pigs and only some in PRL cells of gerbils were found to be devoid of grains. Quantitative analysis revealed that the number of grains per nucleus differed considerably from cell to cell. LH cells of guinea pigs accumulated much larger amounts of 3H-estradiol than did the PRL cells, while the LH cells in the hamsters and gerbils accumulated only slightly more 3H-estradiol than the PRL cells. These results confirm the previous observations in rats and baboons that demonstrated tremendous species differences in percentage of cells in the anterior pituitary gland that accumulated 3H-estradiol. Also, these data suggest that there are functionally heterogeneous cell types among the LH and PRL cells in hamsters, guinea pigs and gerbils as has been previously demonstrated in rats and baboons.

Deficiency of density-dependent regulation of cell growth in the culture of skin fibroblasts from patients with mucolipidosis III

Cultured skin fibroblast cells were prepared from two patients with mucolipidosis III (ML III), which is a genetic disorder characterized by low activities of multiple lysosomal enzymes in fibroblasts. Genetic complementation analysis of fused fibroblast hybrids revealed that the patients were classified in different complementation groups. Growth curves of fibroblasts of ML III patients in culture were compared with those of fibroblasts of Sanfilippo's syndrome patients as well as of the normal fibroblasts. Normal and Sanfilippo fibroblasts gave essentially the same sigmoid curve of cell growth. However, although both ML III cell lines grew at the normal rate in the initial logarithmic phase, they continued to proliferate actively even after the cultures reached confluency. This is the first report to demonstrate the deficiency of density-dependent regulation of cell growth in the culture of nontransformed cell types. Therefore, the culture of skin fibroblasts of ML III patients may serve as a useful experimental model for investigating the regulation of cell proliferation in vitro.

Aberrant composition of chondroitin sulfates in the cartilage-type proteoglycan isolated from the iliac crest of patients with some lysosomal storage diseases

In order to investigate the involvement of cartilage proteoglycans in the pathogenesis of human congenital skeletal disorders, proteoglycans were extracted with 4 M guanidine HCl from the iliac crest cartilage of children with various skeletal diseases; lysosomal storage diseases (group I), osteochondrodysplasias (group II) and controls (group III). The cartilage-type proteoglycan (PG-H) was purified and its chondroitin sulfate moiety was analyzed by digestion with chondroitinase-ABC. In group II and group III, the relative amounts of the unsaturated disaccharide products changed in an age-related manner; decrease (from 50% to 30%) of delta Di-4S with a compensatory increase (from 40% to 60%) of delta Di-6S with increasing age from 0 to 15 years. On the other hand, some cases in group I showed aberrant composition of the disaccharide products; a lower content of delta Di-4S with a correspondingly higher content of delta Di-6S. Patients in group I have clinically similar skeletal disorders, and the extent of the compositional abnormality seems to reflect the severity of the skeletal disorder. Therefore, one may consider that the aberrant composition of the glycosaminoglycans in PG-H is involved in the pathogenesis of the skeletal disorder of lysosomal storage diseases.

Glycosaminoglycans and proteoglycans synthesized by rat limb buds during prechondrogenic and chondrogenic stages

The sulfated glycosaminoglycans synthesized in the forelimb plates of rats on days 12, 13, 14, and 15 of gestation were characterized by their susceptibility to various glycosaminoglycan lyases. On days 12 and 13, heparan sulfate accounted for approximately 65% of the newly synthesized sulfated glycosaminoglycans. Small amounts of dermatan sulfate and chondroitin sulfates were also observed. On day 14, the relative amount of chondroitin 4-sulfate began to increase, there being a compensatory decrease in the amount of heparan sulfate. 35S-Sulfate-labeled material was extracted from day-13 forelimb plates with 4 M guanidine/HCl without proteolysis. Using ultracentrifugation on a sucrose density gradient, the extract was separated into two peaks: a light peak (L) mainly composed of heparan sulfate, and a faster-sedimenting peak (M) mainly composed of chondroitin sulfate. The cartilage-type proteoglycan (H) was first detectable on day 14 of gestation, indicating that chondrogenesis in rat forelimb plates starts on day 14 of gestation. In addition to these previously identified glycosaminoglycans or proteoglycans, we isolated an unknown component in the glycosaminoglycan preparations obtained from limb plates during these developmental stages. This component was not found in glycosaminoglycan preparations obtained either from the brain or tail of rat fetuses at the same stages.

Polydactyly and polysyndactyly of the fifth toe

Classification and treatment of polydactyly and polysyndactyly of the fifth toe are described based on a study of 37 patients with 46 affected feet. Polydactyly was seen in 26.1% of duplicated toes, polysyndactyly in 28.3%, and polysyndactyly fused with the fourth toe in 45.7%. Thirty-three patients with 42 toes were surgically treated. The medial toe was removed in patients with the duplicated fifth toe fused with the neighboring fourth toe; if necessary, a free full-thickness skin graft was performed on the fourth toe and not on the fifth toe. Either the lateral or the medial fifth toe was excised for better contour of the forefoot in patients with polysyndactyly without fusion with the fourth toe. The lateral digital ray, including the metatarsal, was excised in patients with polydactyly of the metatarsal type. The average age of patients at operation was 12.3 months (range, five days to five years). Reorganization of the foot was facilitated when the child was treated early or before it could walk.

Phasic changes in immunocytochemical stainability of pituitary luteinizing hormone cells associated with their ultrastructural changes during estrous cycle in the rat

Changes in the immunoreactivity of pituitary luteinizing hormone (LH) cells and in their fine structure were studied in 4-day-cyclic female rats along with the radioimmunoassay of pituitary and serum LH. Pituitary LH increased during diestrus (DE) and in early proestrus (PE) to a maximal level at noon of PE, followed by a marked decrease by 2100 h PE. Serum LH stayed at low levels in estrus (E) and in DE, while they displayed a significant increase at PE. Light microscopic immunocytochemistry distinguished intensely and weakly stained cells using rat LH beta antiserum. The populations of intensely stained cells were 80% at PE, 30% at E and 75% at DE. This suggests that all of the LH cells do not secrete LH synchronously on the afternoon of PE. Immunoreactivity of LH cells was related to the amount of secretory granules stored in the cells as determined by the superimposition technique. Analysis of the LH storage site by the protein A-gold method confirmed that the small secretory granules, which accumulated in LH cells at DE or PE, certainly contain LH. At least two LH cell types were distinguished: one is the oval or polygonal cell with flattened rER numerous mitochondria, abundant small secretory granules (about 200 nm), a well developed Golgi complex, and a round nucleus. The other has similar structural characteristics along with large secretory granules which are more than 300 nm in diameter. At noon of PE almost all of the LH cells were the first type while the second ones were mainly found at DE or E. The relationship of these LH cell types of the male gonadotrophs is discussed.

Congenital bowing of long bones: clinical and experimental study

The mechanism responsible for prenatal bowing of long bones was investigated based on the results of morphological observation and biochemical analysis of glycosaminoglycans of the autopsied bone from a newborn patient with classic campomelic dysplasia and the result of an experiment which produced a similar deformity in rat fetuses. An excised bone with postnatal bowing from a patient with osteogenesis imperfecta was also examined for comparison. In the case of campomelic dysplasia, marked hypertrophic change of the cambium layer of the periosteum at the concave side of the bone was noted. Parallel rays of the periosteal bone extended from the concave (posterior) side toward the apex of the bowing at the anterior side. Increased amounts and differences in composition of glycosaminoglycans were found in the diaphyseal bone on the concave side, suggesting the existence of bone with maturity retardation. In contrast, there were no such differences in the case with postnatal bowing and in the control. Congenital bowing of long bone in the patients with multiple malformations such as campomelic dysplasia is probably manifested as early as the cartilaginous model as the experimental result suggested.

Direct-writing recorder of the frequency dependence of dynamic compliance analyzed from one cycle of breathing and pulmonary resistance: effect of fenoterol on asthmatic subjects

We developed a new method of direct-writing recording of the frequency dependence of dynamic compliance analysed from one cycle of breathing and pulmonary resistance. Both pulmonary resistance (RL) and frequency dependence of dynamic compliance (Cdyn.f) are calculated by Fourier-series analysis of flow and transpulmonary pressure in a single cycle of breathing. RL was obtained from fundamental harmonics. Cdyn.f was calculated from 1st and 2nd harmonics and estimated by the ratio of Cdyn at 0.5 Hz to Cdyn at zero frequency, C0.5/C0. We used fenoterol aerosol which contained 0.2 mg of fenoterol with one puff of aerosol. Two puffs of fenoterol aerosol were used in each subject and followed changes of RL, C0 and C0.5 as long as 30 min. After fenoterol inhalation RL decreased considerably and C0.5/C0 cont [C0.5/(control C0)] increased. With time, while RL was kept stable, C0.5/C0 cont increased further. We suggest that fenoterol has a potent effect on the small airways which is enhanced with time.