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Biomedical subjects

J Chao

Publications and source records attributed to J Chao.

At least 271 records · Page 15Linked to original sources
PubMed1982

Genetic heterogeneity of dynein-deficiency in cilia from patients with respiratory disease.

Impairment of mucociliary clearance as a result of genetic defects of cilia in the respiratory tract has been recognized as a cause of chronic or recurrent respiratory diseases. Respiratory cilia have been examined by high resolution electron microscopy of nasal and bronchial biopsies from children and young adults from 6 months to 24 yr of age. In this series, 17 children with immotile cilia syndrome have been shown to have deficiencies of dynein arms in the cilia. Ultrastructural analysis reveals a variability of dynein defects from the lack of inner arms, the lack of outer arms, to the complete lack of both inner and outer dynein arms. The spectrum of defects that contribute to dynein-deficient cilia presumably reflects separate genetic determinants, affording further evidence that the immotile cilia syndrome is genetically heterogeneous. Despite ultrastructural differences in cilia, no significant differences are evident in the clinical course of the respiratory disease in affected subjects or in the incidence of situs inversus that affects 50% of subjects.

Adenosine Triphosphatases↗
PubMed1982

Human plasma inactive renin: purification and activation by proteases.

A new affinity chromatographic procedure was devised to purify inactive renin by using a selective hydrophobic interaction of inactive renin to octyl-Sepharose. Additional extensive purification was accomplished by immunoaffinity chromatography on antihuman renin immunoglobulin G-Sepharose. A trace amount of active renin was removed by chromatography on pepstatin-Sepharose. Human plasma inactive renin purified by this method was free from protease inhibitors and permitted the investigation of protease-mediated activation without the acid treatment which was used previously to remove inhibitors. Human plasma kallikrein, human plasmin, cathepsin B1, and arginine esteropeptidases associated with mouse epidermis growth factor and nerve growth factor were effective activators. Human urinary kallikrein, hog pancreatic kallikrein, and rat urinary esterase A were inefficient activators of low potency. Thrombin, factor Xa, factor XIIa, and urokinase did not activate inactive renin. The in vitro activation of 56,000-dalton inactive renin by these proteases was not accompanied by a recognizable reduction in molecular weight. Activation required plasma albumin, presumably as a protecting substance. These results suggest that human inactive renin can be activated by a minimum change in its molecular size.

Cathepsin B↗
PubMed1982

A method for determination of human urinary inactive kallikrein (prekallikrein).

Inactive kallikrein (prekallikrein) in human urine was discovered recently. A more accurate method to measure this zymogen and total kallikrein is described. With trypsin pretreatment, it was found that 35.3 +/- 2.7% of total urinary kallikrein activity was prekallikrein. The results are supported by a new direct radioimmunoassay which measures predominantly active kallikrein.

Adult↗
PubMed1981

Kallikrein-induced uterine contraction independent of kinin formation.

Responses of smooth muscle to kallikreins (EC 3.4.21.8) are generally considered to result from kinin formation. This premise was reexamined with the isolated rat uterus. Rat urinary kallikrein or bradykinin produced dose-dependent contractions of rat uterus but kallikrein was 5-fold more potent than bradykinin. Kallikrein caused an immediate series of rhythmic contractions which could be increased gradually with subsequent addition of kininogen substrate. Kallikrein-induced contractions were unaffected by carboxypeptidase B or a bradykinin antiserum whereas bradykinin-induced contractions were attenuated or abolished. Other serine proteinases, including trypsin, either did not induce contraction in the absence of added kininogen or did so minimally. Although small amounts of kininogen-like substrate were found in uterine tissue, detectable kinin levels (greater than 4 pg) could not be found in bathing media during maximal kallikrein-induced contractions or after uterine tissue was incubated with high concentrations of the enzyme in the presence of SQ 20881, a kininase II inhibitor. The data suggest that uterine contraction produced by a homologous kallikrein does not involve kinin formation but results from an action of this serine proteinase upon other accessible systems coupled to the contractile response.

Animals↗
PubMed1981

Excretion of human urinary kallikrein quantity measured by a direct radioimmunoassay of human urinary kallikrein in patients with essential hypertension and secondary hypertensive diseases.

Recently, we established a very sensitive, specific and simple direct radioimmunoassay method for human urinary kallikrein. In this study, in order to clarify whether or not the low or high excretion rate of urinary kallikrein activity in patients with essential hypertension, primary aldosteronism, pheochromocytoma and Bartter's syndrome is caused by changes in enzyme quantity, urinary kallikrein excretion was measured with this direct radioimmunoassay method in normal subjects and in patients with these diseases. Urinary kallikrein excretion measured as enzyme quantity was significantly lower in patients with essential hypertension, and higher in patients with primary aldosteronism and Bartter's syndrome. These results are consistent with other previously reported data and our data measured by means of esterase assay or kininogenase assay. The results also suggest that lowered or elevated excretion of urinary kallikrein activity in these diseases is caused, in part at least, by the lowered or elevated excretion of enzyme quantity.

Bartter Syndrome↗
PubMed1981

Active-site labeling of rat and human urinary kallikrein by chloro(N alpha-p-tosyllysyl)methane.

This is the first report to demonstrate that chloro(N alpha-p-tosyllysyl)methane (TosLys-CH2Cl) inhibits mammalian glandular kallikrein activities. The inhibitory effect of TosLysCH2Cl on purified rat urinary kallikrein was carried out with three assay methods: 1) Tos-Arg-OMe hydrolysis activity measured by a radiochemical method; 2) kininogenase activity using purified bovine low molecular weight kininogen as substrate and the released kinins subsequently measured by radioimmunoassay; 3) bioassay using isolated rat uterus preparation. Purified rat urinary kallikrein was inhibited by TolLysCH2Cl in a dose and time-dependent manner with all three methods used. The inhibition of purified human urinary kallikrein esterase and kinin-releasing activities were also demonstrated. The results indicate that TosLysCH2Cl inactivates kallikrein activity and support the notion that reactive histidine residue(s) participates in the active center of Kallikrein for catalysis.

Amino Acid Chloromethyl Ketones↗
PubMed1980

Amiloride inhibits mammalian renal kallikrein and a kallikrein-like enzyme from toad bladder and skin.

Renal kallikrein is localized in luminal plasma membranes of the mammalian distal nephron and gains access to urine from this site. Its activity is regulated, in part, by aldosterone. These facts led us to study the effects of amiloride, a drug known to inhibit sodium reabsorption and potassium secretion at this site, on kallikrein activity. Amiloride inhibited the esterolytic activity of purified rat or human urinary kallikrein or of rat renal cortical cells upon a synthetic substrate (ID50 = 0.12-0.23 mM). Kinetic analyses showed that the enzyme inhibition was noncompetitive and reversible in nature. The kinin-generating activity of kallikrein acting upon kininogen substrates was also inhibited by amiloride, as measured by bioassay in the rat uterus of guinea pig ileum or by radioimmunoassay of liberated kinins (ID50 = 85 microM). No other diuretic drug tested inhibited kallikrein activity, except triamterene, which did so, weakly. In addition, kallikrein-like enzyme activity was discovered in the urinary bladder or skin of Bufo marinus toads and this activity was also inhibited by amiloride. The localization of the enzyme and its inhibition by this drug suggest that further study of relationships amongst the glandular kallikrein-kinen system and renal ion and water transport is warranted.

Amiloride↗
PubMed1980

The radioimmunoassay of human urinary kallikrein and comparisons with kallikrein activity measurements.

Human urinary kallikrein was purified to homogeneity, and an antiserum to it was raised in rabbits. A RIA was devised which uses this rabbit antiserum (Keq = 2.75 x 10(11) M-1) in a final dilution of 1:2,500,000 and the purified kallikrein labeled with 125I using a lactoperoxidase method. Assay sensitivity is 8 pg kallikrein. Thus far, the assay is specific for human and perhaps monkey urinary kallikrein. Correlations between this assay of immunoreactive kallikrein and the alpha-N-Tosyl-L-arginine-[3H]methylester (Tos-Arg-OMe) activity method or a kininogenase assay were highly significant (r = 0.94 and 0.96, respectively) and show that each assay measures human urinary kallikrein comparably. Low or high dietary sodium intakes, maneuvers known to change human urinary Tos-Arg-OMe esterase excretion, change immunoreactive kallikrein to an equivalent degree. Normal black children, already known to excrete significantly less Tos-Arg-OMe esterase than white children, excrete similarly reduced amounts of immunoreactive kallikrein. Kallikrein excretion in children with cystic fibrosis of the pancreas was not different from that in normal children. The data show that a specific and sensitive direct RIA for human urinary kallikrein has been developed and that both the Tos-Arg-OMe esterase and kininogenase assays measure human urinary kallikrein activity specifically, at least in the described circumstances.

Animals↗
PubMed1980

Kallikrein content of rat pancreatic acinar cells or islets by direct radioimmunoassay.

Recent reports have suggested that kallikreins may enzymatically convert proinsulin to insulin. The quantity of rat pancreatic kallikrein in isolated Islets of Langerhans, acinar cells and in whole pancreatic extracts was measured by direct radioimmunoassay and bioassay. Immunoreactive kallikrein content in acinar cells was 813 +/- 111 ng/mg protein (mean +/- S.E.M.). In whole pancreatic homogenates, it was 1303 +/- 213 ng/mg protein. Appreciable quantities of the enzyme were not detected in islets. Kallikrein activity as measured with a rat uterine bioassay had similar distribution. Because of the localization of kallikrein, it is unlikely that the enzyme is involved in the in vivo conversion of proinsulin to insulin.

Animals↗
PubMed1979

Studies on rat renal cortical cell kallikrein. II. Identification of kallikrein as an ecto-enzyme.

Suspensions of viable renal cortical cells hydrolyzed a synthetic ester substrate (alpha-N-tosyl-L-arginine methyl ester, Tos-Arg-OMe) and generated kinins from a kininogen substrate. This kallikrein-like esterase activity increased linearly with cell number, or time of exposure to substrate. No radiolabelled substrate or product was found within the cells. Most of the activity appeared to be on cell surfaces as supernatant media had less than 20% of the Tos-Arg-OMe esterase activity on the cell suspensions. Cell surface Tos-Arg-OMe esterase activity was inhibited by aprotinin, benzamidine, pentamidine, and a tris-amidine derivative (alpha,alpha',alpha''-tris(3-amidinophenoxy)mesitylene). Preincubation of cells with phospholipase A2 increased renal cell surface esterase activity up to 76% while only slightly increasing supernatant activity. In contrast, preincubation with deoxycholate caused clearing of suspensions and a marked increase in supernatant esterase activity. Renal cell kininogenase (EC 3.4.21.8) activity was inhibited by preincubation with aprotinin, the tris-amidine derivative, or anti-rat urinary kallikrein antibody. Kallikrein elaborated by renal cells formed a single precipitin line with an antibody to rat urinary kallikrein but the two enzymes were not immunologically identical. We conclude that kallikrein's active sites are facing the external environment of renal cortical cells in suspension with access to substrates, inhibitors, and antibody.

Animals↗
PubMed1979

Cilia with defective radial spokes: a cause of human respiratory disease.

We studied the fine structure of respiratory-tract cilia in three siblings with chronic respiratory disease, comparing them with those from a patient with Kartagener's syndrome who had dynein-deficient cilia and with control patients who had chronic bronchitis or chronic sinusitis. Electron microscopy of the siblings revealed a new abnormality in the ciliary axoneme--namely, lack of the radial spokes. Their cilia showed an eccentric central pair of tubules but otherwise had a normal central sheath, outer-doublet microtubules, nexin links and dynein arms. The cilia were immotile. Mucociliary clearance was completely lacking in the three siblings and in the patient with Kartagener's syndrome, but was normal in their parents and unaffected siblings. Sperm from the male sibling showed identical structural abnormalities and were immotile. We consider the radial spoke defect to be the congenital anomaly responsible for dysfunction of the mucociliary clearance mechanism in these three patients and of the immotile sperm in one of the them. This defect is apparently another cause of the "immotilecilia syndrome."

Adult↗
PubMed1979

Kallikrein localization in rodent salivary glands and kidney with the immunoglobulin-enzyme bridge technique.

Kallikrein has been localized in rodent kidney and salivary glands by means of an immunoglobulin-enzyme bridge technique. In sections of kidney, anti-kallikrein antibodies bound to the apical region of certain distal tubule segments in the cortex, to reabsorption droplets of proximal convoluted tubules, and to certain duct segments in the papilla. In salivary glands of both male and female rats and mice, and apical rim of most striated duct cells of submandibular, parotid and sublingual glands and granular tubules of submandibular glands exhibited immunoreactivity. Granular intercalated duct cells in female submandibular glands also displayed immunostaining for kallikrein. Phenylephrine administration resulted in loss of immunoreactive granules from the granular convoluted tubule cells of male mouse submandibular gland. This response was paralleled by a biochemically demonstrable decrease in kallikrein-like tosylarginine methyl ester (TAME) esterase activity.

Animals↗
PubMed1979

A direct radioimmunoassay of rat urinary kallikrein and comparison with other measures of urinary kallikrein activity.

A highly sensitive radioimmunoassay for rat urinary kallikrein (minimal detectable amount, 40 pg/tube) has been developed. The assay uses a sheep antibody (Keq = 3.25 X 10(10)M-1) against purified Sprague-Dawley rat urinary kallikrein in a final dilution of 1 : 1,200,000. The assay incorporates a convenient and inexpensive PEG technique for separation of free from bound antigen. Parallel standard curves with rat urine or kidney homogenates were obtained. No cross-reactivity with human or dog urine samples or purified human urinary kallikrein was seen. Correlations among this assay, an esterolytic method, and a kininogenase radioimmunoassay for kallikrein were highly significant, with only the esterolytic assay demonstrating any significant nonspecificity. The radioimmunoassay can detect changes in urinary kallikrein levels produced by a maneuver known to alter urinary kallikrein excretion.

Animals↗