Effect of vitamin D metabolites on calcitriol degradative enzymes in renal failure

We have demonstrated that in renal failure calcitriol degradation is decreased and that administration of vitamin D metabolites increases the degradation. In this study, we measured intestinal 24- and 26-hydroxylase activities and the effects of chronic infusion (7 days) of vitamin D metabolites on these enzymes' activities in rats with experimental renal failure. The enzymatic activity of intestinal 24-hydroxylase, but not 26-hydroxylase, was significantly lower in renal failure rats compared to control sham operated rats. Replacement of calcitriol (3 ng/day) significantly increased 24-hydroxylase activity by 17% in rats with renal failure (P < 0.01), although the activity remained 15% lower than the controls (P < 0.01). Intestinal 26-hydroxylase activity was not lower in renal failure; however, calcitriol treatment increased the activity beyond that of normal controls. In contrast, administration of 25(OH)D3 (600 ng/day) and 24,25(OH)2D3 (1 microgram/day) reduced the conversion of calcitriol to 1,24,25(OH)3D3 by more than 50% and to 1,25,26(OH)3D3 by more than 38%, respectively. We conclude that calcitriol increased its own degradation in renal failure by increasing the enzymatic activities of both 24- and 26-hydroxylase. However, the mechanisms of increased calcitriol degradation by 25(OH)D3 and 24,25(OH)2D3 in renal failure remain unknown.

Effects of terbutaline on alpha-adrenergic responses and Ca2+ influx in isolated rabbit aorta

Effects of terbutaline applied in vivo or in vitro on alpha-adrenergic receptors in the rabbit aorta in normal and Ca(2+)-free solution, and on basal, high potassium-, and phenylephrine-stimulated Ca2+ uptake into aorta were investigated. Three day terbutaline administration (25 mg/kg, subcutaneously three times daily) to rabbits increased the pKB for phentolamine in aorta rings (control 7.3 +/- 0.2, n = 9; terbutaline 7.8 +/- 0.2, n = 15). It also depressed phenylephrine-stimulated contractions of aorta rings in Ca(2+)-free but not those in normal Krebs solution. It did not significantly depress the basal, or phenylephrine-evoked Ca2+ influx into aorta rings, but decreased high potassium-induced Ca(2+)-influx (control 0.58 +/- 0.05 mumoles/g aorta; n = 3, terbutaline 0.41 +/- 0.06 mumoles/g aorta, n = 3). In vitro application of 50 microM terbutaline did not significantly alter phenylephrine-stimulated contractions of aorta rings in Ca(2+)-free Krebs solution or significantly depress basal or phenylephrine-induced Ca2+ influx into aortas, but did decrease high potassium-stimulated Ca(2+)-influx. Thus, 3-day terbutaline administration increased the affinity of alpha-adrenergic receptors for phentolamine and had a tendency to increase contractions of aorta rings to phenylephrine. It also decreased high potassium-stimulated Ca2+ influx, and depressed phenylephrine-induced contractions in Ca(2+)-free Krebs solution, while in vitro terbutaline application also decreased potassium-induced Ca2+ influx.

Tissue distribution of 3H-terbutaline in rabbits

Terbutaline is a widely used, selective beta 2-adrenergic agonist whose penetration into brain has not been demonstrated in laboratory animals. Although its tissue uptake has been reported in some animals, no uptake into brain has been demonstrated. A single dose of 20 microCi of 3H-terbutaline along with 10 mg/kg of unlabeled terbutaline was injected into a rabbit marginal ear vein. The distribution of 3H-terbutaline in several tissues was determined 0.5, 1, 3, or 6 hr later. Radioactivity in the brain was well-maintained over the 6 hr observation period. In most tissues, radioactivity peaked in less than 1 hr, then declined. Radioactivity in the urine was high at all time periods and was highest at 3 hr. Thus, terbutaline or a metabolite(s) does cross the blood-brain barrier in rabbits, and the radioactivity in the rabbit brain does not decrease during the 6 hours following terbutaline injection.

Acute segmental obstructing enteritis in children

We studied a group of 15 children with acute segmental enteritis associated with intestinal obstruction. The disease is characterized by fever, leukocytosis, copious bilious vomiting, and severe abdominal pain with signs of intestinal obstruction. Exploration revealed varying degrees of segmental ischemic change in the small bowel, but surgery seemed to be unnecessary in most cases. Antibiotics were effective in nonoperative cases. The clinical illness lasted 10-14 days. The disease was self-limited, and no mortality was found in our series. To our knowledge, this is the first report of this disease entity in Chinese children.

Duplex ultrasonographic assessment of gut blood flow velocity: effect of meal composition in normal full-term newborns after first feed

We used transcutaneous duplex Doppler ultrasound to measure superior mesenteric artery and celiac artery blood flow velocity in 45 normal healthy newborn infants. Doppler indices of PSV, TAMV, EDV, and PI were measured immediately before and after feeding at 15 minute intervals up to 75 minutes. Maximal changes were compared with preprandial baseline values. There were no significant differences between the preprandial and postprandial blood pressures and heart rates. In the superior mesenteric artery the PSV, TAMV, and EDV rose progressively and peaked 30 minutes after feeding in both the milk-fed group and the 5% glucose, water-fed group over baseline (73 versus 41% and 110 versus 63%, 130 versus 100%) (P < 0.05). The PI decreased significantly in the milk-fed group only. There were no significant changes in any blood flow velocity parameters derived from the celiac artery. We conclude that duplex ultrasonography provides a noninvasive means of studying the reactivity of the splanchnic arterial circulation to different stimuli. The chemical composition of the meal is a significant factor determining postprandial mesenteric hyperemia.

Computerized Dysmorphology Database Mackay (CDDM): preliminary report

A computerized dysmorphology database is useful for the pediatrician and geneticist in the task of diagnosing multiple malformation syndromes in children. We set up a new dysmorphology database "Computerized Dysmorphology Database Mackay (CDDM)" managed by the Clipper program. At present 278 disease entities with their clinical features and references are stored in the database. In this article, we report a practice analysis of ten dysmorphic patients by CDDM. A specific syndrome was accurately and rapidly diagnosed with the aid of CDDM in all ten cases. They serve as examples on how CDDM can be efficiently applied to obtain a short list of syndromes for differential diagnosis.

Obturator hernia: a report of eight cases

Obturator hernia is a rare problem that occurs predominantly in elderly, emaciated women. The diagnosis of obturator hernia is difficult to establish in most patients before an operation is performed. Both delayed diagnosis and delayed surgical intervention contribute to high mortality. From 1978 to 1992, eight cases of obturator hernia involved elderly females who had received operations at this hospital. Resection of the incarcerated bowel was required. The often debilitated condition of these patients and the frequent delay of diagnosis combined to produce significant operative mortality.

Pulmonary artery sling with tracheo-bronchial stenosis: report of one case

This patient is a 6-month-old female baby with intermittent symptoms of air-way obstruction for two months. The diagnostic examinations performed included: esophagogram, two-dimensional echocardiography, cardiac catheterization with selective right pulmonary arteriography, magnetic resonance imaging (MRI) and tracheo-bronchogram. The esophagogram revealed anterior indentation of the esophagus. The echocardiogram, cardiac catheterization and MRI all demonstrated anomalous origin of the left pulmonary artery from the right pulmonary artery instead of the main pulmonary artery. The tracheo-bronchogram showed long-segment stenosis of the lower portion of the trachea. A final diagnosis of pulmonary artery sling with tracheo-bronchial stenosis was made. Since the parents refused surgery, the baby expired after several episodes of cyanosis & cardiac arrest.

Effect of uric acid on plasma levels of 1,25(OH)2D in renal failure

Previous studies from these laboratories have demonstrated that uremic biologic fluids contain substances that suppress 1,25(OH)2D metabolism. Among these substances, it was found that uric acid suppresses 1 alpha-hydroxylase activity and synthesis of 1,25(OH)2D in rats. In this study, the effect of uric acid on plasma concentrations of 1,25(OH)2D in patients with renal failure was examined. Nine patients with stable chronic renal failure (serum creatinine, 1.9 to 6.4 mg/dL) were studied. None of the patients received vitamin D supplementation. Plasma concentrations of Ca, P, parathyroid hormone, creatinine, uric acid, 1,25(OH)2D, and 25(OH)D were measured before and 1 wk after the patients received allopurinol, 300 mg daily. Plasma creatinine, Ca, P, parathyroid hormone, and 25(OH)D did not change before or after allopurinol treatment. However, plasma uric acid decreased significantly from 7.3 +/- 0.4 to 4.0 +/- 0.4 mg/dL (P < 0.01) and plasma concentration of 1,25(OH)2D rose from 30.8 +/- 2.7 to 38.2 +/- 4.8 pg/mL (P < 0.01) after the ingestion of allopurinol. Allopurinol itself did not appear to directly enhance 1 alpha-hydroxylase activity in rats. It was concluded that a short-term administration of allopurinol suppresses plasmic uric acid and increases plasma 1,25(OH)2D in patients with chronic mild to moderate renal failure.

[Clinical study of infants with birth weight less than 1500 grams]

One hundred and seventy-seven infants of birth weight less than 1500 grams admitted to the neonatal intensive care unit of Mackay Memorial Hospital in 1987 were studied. The sex distribution, male to female ratio was 100:77, inborn 78 cases, outborn 99 cases. At one year follow-up, the mortality rate of these weighed between 500 gm and 799 gm was 100%, between 800 gm and 999 gm 54%, between 1000 gm and 1249 gm 17%, between 1250 gm and 1499 gm 19% respectively. The mortality rate of outborns was higher than that of inborns (X2 = 6.03, P < .05). The most common cause of mortality of these infants was intracranial hemorrhage, it accounts for 55% of the mortality. Seventy-three percent of the deceased cases expired during the first three hospitalization days. Of these 177 cases, 94 were put on respirator with IPPB initially, another 47 cases were on nasal CPAP. Only 36 cases didn't require respiratory therapy. Complications of the extreme prematurity and management including intraventricular hemorrhage, pulmonary hemorrhage, sepsis, pneumothorax, persistent pulmonary hypertension, disseminated intravascular coagulopathy, electrolyte imbalance, bronchopulmonary dysplasia and retinopathy of prematurity were discussed. In order to improve survival and reduce complications of these extreme prematurity, advanced monitoring system, early detection and prevention of intracranial hemorrhage, establishment of the transport system are essential.

Duplex Doppler assessment of visceral and cerebral blood flow velocity in full-term newborns

To assess postnatal visceral and cerebral blood flow velocity changes, transcutaneous duplex Doppler ultrasound was used to measure the superior mesenteric artery (SMA), celiac artery (CA) and anterior cerebral artery (ACA) blood flow velocity in 20 normal healthy newborns. Doppler indices of peak systolic velocity (PSV), time-averaged mean velocity, end-diastolic velocity and Pourcelot resistance index (PI) were measured immediately after delivery and consecutively for three days at 24-hour intervals. At 24 hours after delivery, PSV had risen significantly in the CA, SMA and ACA (p < 0.01). The PI had decreased significantly in all three vessels. We conclude that the most prominent hemodynamic changes in the splanchnic and cerebral artery circulation occur within 24 hours after delivery in normal healthy newborns. Possible mechanisms are discussed.

Monocyte 1 alpha-hydroxylase regulation: induction by inflammatory cytokines and suppression by dexamethasone and uremia toxin

Alveolar macrophages acquire 1 alpha-hydroxylase activity in inflammation, and thereby metabolize 25 hydroxyvitamin D3 (25 D3) to the active metabolite, 1 alpha,25-dihydroxyvitamin D3 (1,25 D3, calcitriol). Calcitriol is a potent differentiation agent that modulates mononuclear phagocyte activation and effector functions. The mediators that induce macrophage 1 alpha-hydroxylase activity are not well delineated. Furthermore, it is unclear whether calcitriol is a product only of terminally differentiated macrophages or whether less mature mononuclear phagocytes can produce it as well. The ability of newly recruited monocytes to produce calcitriol as an autocrine differentiation agent is particularly important in inflammation, as it may substantially expand the functional repertoire of these cells. To assess the effects of cytokines on 1 alpha-hydroxylase activity, blood monocytes were cultured in the presence and absence of human recombinant tumor necrosis factor alpha (TNF-alpha), interferon-gamma (IFN-gamma), and interleukins 1 and 2 and then incubated with 25 D3 substrate. The conditioned media were assayed for calcitriol by high-performance liquid chromatography and competitive receptor binding assay. No detectable calcitriol was produced by unstimulated monocytes. However, all the cytokines markedly increased monocyte calcitriol production (range 133-151 pg/mg protein; in all cases P < .001). We then determined whether calcitriol production was suppressed by preincubation with either dexamethasone or the putative uremia toxin guanidinosuccinic acid (GSA). Dexamethasone pretreatment significantly inhibited subsequent cytokine-induced calcitriol production by monocytes, as did GSA (average 69 and 63% of control, respectively).

Efficacy of plasmin-treated intravenous gamma-globulin for therapy of Kawasaki syndrome

In order to delineate the efficacy of plasmin-treated intravenous gamma-globulin (IVGG) in the treatment of Kawasaki syndrome, we compared the frequency of coronary artery abnormalities in children treated or not with IVGG for Kawasaki syndrome. Among 291 cases of Kawasaki syndrome diagnosed during the period of 1987 to 1991 without coronary abnormalities within 10 days of the onset of illness, 128 were treated with IVGG and aspirin and were compared with 163 treated with aspirin alone. IVGG was given in a dosage of 400 mg/kg/day for 4 consecutive days. The detection of coronary abnormalities was monitored by two dimensional echocardiography. Two weeks after enrollment coronary artery abnormalities were present in 37 (22.7%) of 163 children in the aspirin group and in 9 (9%) of 128 in the gamma-globulin group (P < 0.05). Seven weeks after enrollment, abnormalities were present in 20 (12.3%) of 163 children in the aspirin group and in 6 (4.6%) of 128 in the IVGG group (P < 0.05). We conclude that plasmin-treated IVGG is effective in reducing the prevalence of coronary artery abnormalities in Kawasaki syndrome and suggest a predominant role of the Fc gamma fragment of IgG in the therapeutic effect.

Mechanism of decreased intestinal calcitriol receptor concentration in renal failure

The biological actions of calcitriol and its receptor synthesis are believed to be mediated through the calcitriol-receptor complex interacting with nuclear chromatin of target cells. Thus inhibition of the receptor interaction with DNA could diminish the biological actions of calcitriol and upregulation of its receptor. We found that uremic ultrafiltrate reduced the receptor interaction with DNA in vitro. DNA-cellulose chromatography showed that the receptor from normal rats and rats infused with normal ultrafiltrate eluted as a single peak at 0.22 M KCl, whereas chronic renal failure rats and rats infused with uremic ultrafiltrate had two receptor peaks, i.e., one of normal activity at 0.22 M KCl and the other of weak activity at 0.12 M KCl. Furthermore, infusion of uremic ultrafiltrate to normal rats reduced the intestinal calcitriol receptor concentration (397 +/- 15.8 vs. 307 +/- 15.4 fmol/mg protein, both n = 4, P < 0.005). Uremic ultrafiltrate also suppressed the calcitriol-induced upregulation of the receptor (816 +/- 34.6 vs. 606 +/- 35.3 fmol/mg protein, P < 0.005). It appears that uremic toxins may reduce the biological action of calcitriol in renal failure by inhibiting receptor synthesis and the interaction of the hormone-receptor complex with nuclear chromatin.

Liver transplantation for a hepatitis B-related cirrhotic patient

A patient with chronic end-stage liver cirrhosis resulting from a hepatitis B viral infection had a successful liver transplantation performed on 1 July 1991. Preoperative serology revealed that both HBsAg and HBeAg were positive, and the anti-HBs antibody was negative. Immunoprophylaxis included active immunization, as well as injections of large doses of hepatitis B immunoglobulin (HBIG) given perioperatively to reverse the antigen status. The patient has been anti-HBs antibody positive for more than 10 months since the transplantation. The immunoprophylaxis protocol used has been effective in the prevention of hepatitis B viral reinfection.

Uremic plasma contains factors inhibiting 1 alpha-hydroxylase activity

The effect of uremic plasma ultrafiltrate on calcitriol synthesis was investigated. Renal 1 alpha-hydroxylase activity was measured in normal rats infused for 20 h with 20 mL of normal or uremic plasma ultrafiltrate. Renal 1 alpha-hydroxylase activity was determined by the generation of calcitriol measured 5, 10, 20, and 30 min after the reaction was initiated by the addition of cold 25(OH)D3. The activity was significantly lower in rats infused with uremic plasma ultrafiltrate. Kidney homogenates preincubated for 3 h with uremic plasma ultrafiltrate also had significantly lower renal 1 alpha-hydroxylase activity than did those preincubated with normal plasma ultrafiltrate. In addition, the effect of the putative uremic toxin, guanidinosuccinic acid (GSA), on renal 1 alpha-hydroxylase activity was studied. Normal rats infused for 20 h with 20 mL of saline solution containing 1.5 mg/dL of GSA had significantly lower renal 1 alpha-hydroxylase activity than did rats infused with normal saline. The enzyme activity was also lower in kidney homogenates preincubated for 3 h with 4 mg/dL of GSA. Enzyme kinetic analysis revealed that the inhibition of renal 1 alpha-hydroxylase by GSA was noncompetitive. It was concluded that uremic plasma contains substances that directly inhibit renal 1 alpha-hydroxylase activity.

Mechanism of decreased calcitriol degradation in renal failure

Metabolic clearance rate (MCR) of calcitriol is decreased in renal failure, and uremic toxins play a major role in the suppression of calcitriol degradation. In this experiment, we studied the effect of uremic toxins on renal 24- and 26-hydroxylase (HX) activities. Normal rats were infused for 20 h with 30 ml of normal or uremic plasma ultrafiltrates. At the end of infusion, renal enzymes activities were measured by the generations of 1,24,25- and 1,25,26-trihydroxyvitamin D3 10 min after the addition of 25 nM or 1 microM calcitriol. Renal 24-HX activity decreased approximately 50%, whereas 26-HX activity did not decrease in rats infused with uremic plasma ultrafiltrate. The induction of 24-HX activity by 100 ng calcitriol also decreased in rats infused with uremic ultrafiltrate. To examine whether uremic ultrafiltrate could directly inhibit the degradation enzymes, 24- and 26-HX activities were measured in kidney homogenates preincubated for 3 h with either normal or uremic ultrafiltrate. Uremic ultrafiltrate did not directly suppress 24- and 26-HX activities. Furthermore, the disappearance rate of calcitriol was similar for 90 min in kidney homogenates after they were preincubated for 3 h with uremic and normal ultrafiltrates. Because 24-HX synthesis is induced by the calcitriol-receptor complex binding to nuclear chromatin and activating genes coding for the enzyme, we studied the effect of uremic toxins on the binding affinity of calcitriol-receptor complex for DNA-cellulose. Uremic ultrafiltrate significantly reduced the binding affinity of the hormone receptor complex for DNA when the receptor was preincubated with the ultrafiltrate for 3 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification of radioiodinated human insulin by high performance liquid chromatography for a sensitive radioimmunoassay

The optimal sensitivity of a radioimmunoassay depends on the purity of the radiolabeled antigen. The conventional purification methods are not complete and are time consuming. The combination of a Sep-pak C18 cartridge and high performance liquid chromatography (HPLC) for the purification of 125I-labeled insulin in our study revealed that the Sep-pak cartridge can serve as the preliminary step to remove unreacted radioactive iodide, the reactants, and labeled but presumably damaged materials unadsorbed to the cartridge. The fractions eluted from the Sep-pak containing high radioactivity and high immunoreactivity to the antibody were chosen for further purification by HPLC to eliminate undesirable radiolabeled substances with a lesser immunoreactivity. The purified radiolabeled insulin was used to develop a sensitive radioimmunoassay with detecting limits of 0.03 microU/mL per tube.

Subfractions in uremic plasma ultrafiltrate inhibit calcitriol metabolism

Previous study from our laboratory has demonstrated that uremic plasma ultrafiltrate suppresses both the production rate (PR) and metabolic clearance rate (MCR) of calcitriol in normal rats. To characterize the the substances responsible for the suppression of the synthesis and degradation of calcitriol, we fractionated 20 ml uremic plasma ultrafiltrates into 13 fractions using high-performance liquid chromatography (HPLC) and studied the effect of each fraction on calcitriol metabolism. We measured the MCR and PR of calcitriol in normal rats after they were infused for 20 hours with each fraction dissolved in 20 ml normal saline. Using a UV absorption and fluorescence emission technique, several known uremic compounds were identified as individual peaks corresponding to the fractions. We found that fractions 4, and 6 to 13 markedly reduced the MCR of calcitriol. The patterns of the MCR suppression by the HPLC fractions suggest that there were at least two groups of chemically distinguishable compounds. Infusion of a solution containing all 13 fractions of the uremic ultrafiltrate also inhibited the calcitriol synthesis. One of the 13 fractions (fraction 4, containing uric acid, xanthine, and hypoxanthine) was further fractionated into eight subfractions. Infusion of subfractions 4 to 7 markedly reduced both the PR and MCR of calcitriol. We conclude that uremic plasma ultrafiltrate contains factors that inhibit calcitriol synthesis and degradation. These substances have molecular weight less than 2,000 Daltons.

Stimulation of 22Na+ efflux from rat forebrain membrane vesicles by L-glutamic acid, L-aspartic acid and kainic acid

A glass fiber filter assay method is described for measuring 22Na+ efflux stimulated by L-glutamic acid, L-aspartic acid and kainic acid from osmotically sensitive membrane vesicles prepared from rat brain. L-Glutamic acid and L-aspartic acid showed the greatest efficacy for the stimulation of 22Na+ efflux with EC50 values of 3 microM. Kainic acid produced 28% of the maximal efflux seen with L-glutamic acid or L-aspartic acid with an EC50 value of 1.5 microM. Quisqualic acid never showed statistically significant increases in 22Na+ efflux over control experiments. N-Methyl-D-aspartic acid showed no detectable efflux activity in this preparation. DL-2-Amino-4-phosphonobutyric acid (APB) inhibited up to 40% of the 50 microM L-glutamic acid-stimulated or 50 microM L-aspartic acid-stimulated 22Na+ efflux with an IC50 value of 1.5 nM. Calcium was required for the inhibitory action of APB, but not for the stimulatory actions of L-glutamic, L-aspartic, or kainic acids. L-Glutamic, L-aspartic, and kainic acids at concentrations above 100 microM were found to inhibit rather than to stimulate 22Na+ efflux. Veratridine (1 microM) had no influence on the 22Na+ efflux component which was produced by L-glutamic or kainic acids. We are unable to firmly establish the mechanism for the stimulated 22Na+ efflux.

Preparation of radioiodinated secretin for radioimmunoassay

Radioiodination of synthetic human secretin on its N-terminal histidyl residue was not difficult when a greater amount of Chloramine T and a longer reaction time were employed to achieve better incorporation of 125I. The radioiodinated tracer for an optimal radioimmunoassay required purification. The combination of Sep-pak C18 Cartridge and high performance liquid chromatography for the purification of 125I-secretin in our study revealed that the Sep-pak cartridge was a preliminary step in removing unlabeled radioactive iodide, the reactant, and labeled materials unadsorbed to the cartridge. The eluate eluted from the Sep-pak containing high radioactivity and high immunoreactivity to the antibody were selected for further purification by HPLC which eliminated undesirable radiolabeled substances with lower immunoreactivity. The purified radiolabeled secretin was used in developing a sensitive radioimmunoassay.

Effects of soman on calcium uptake in microsomes and mitochondria from rabbit aorta

Daily administration of soman for several days results in several alterations in the vascular neuroeffector system. To determine whether or not soman alters intracellular Ca2+ uptake, the effects of acute exposure to soman or 7-day administration of 5 micrograms kg-1 of soman on the capacity of microsomes and mitochondria from rabbit aortic vascular smooth muscle to take up 45Ca2+ were determined. Acute exposure to soman concentrations of 1-100 microM did not alter significantly (P greater than 0.05) 45Ca2+ uptake by either microsomes or mitochondria. On the other hand, 7-day soman administration markedly reduced (P less than 0.05) 45Ca2+ uptake by both microsomes and mitochondria. Thus, calcium uptake and intracellular calcium uptake-dependent responses will be affected by repeated soman administration.

Determination of Giardia lamblia cyst infective dose for the Mongolian gerbil (Meriones unguiculatus)

The purpose of this study was to determine the 50% infective dose for Giardia lamblia (CDC:0284:1) cysts in Mongolian gerbils (Meriones unguiculatus). The log10 50% infective dose results calculated by probit analysis and the Spearman-Karber method were 2.45 and 2.50, respectively.