Measuring clinical attachment: reproducibility of relative measurements with an electronic probe

During the past few years, improvements in detecting longitudinal changes in clinical attachment or alveolar bone density have been introduced. For example, constant-force electronic probes and computer-assisted subtraction analysis of longitudinal radiographs have been reported to be more sensitive and reproducible in detecting changes in clinical attachment or alveolar bone density, respectively. Use of these new technologies requires that sources of measurement error be identified and their contribution quantified. This study investigated the reproducibility of a constant-force electronic probe in a careful clinical setting. Measurements were performed from individually fabricated acrylic stents. Three groups of subjects were selected for the study: 10 adults without oral disease, 10 adults with gingivitis, and 10 adults with moderate periodontitis. Four probing designs were employed to investigate the reproducibility of the probe. In design A, the probe tip was left in the sulcus between successive probings. In design B, the probe tip was removed from the gingival margin between probings but the next probing followed immediately. In design C, successive whole-mouth probings were interrupted by a 5-minute interval and a mouth rinse. In design D there was a 4-week interval between each successive probing. Three measurements were taken at each site for each design. The main purpose of this study was to identify variance components in the attachment level variation. The maximum probing error standard deviation ranged from 0.2 to 0.3 mm depending on the periodontal health of the subject. This level of variation is considerably smaller than that found in most previous studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproducibility of an electronic probe in relative attachment level measurements

4 probing designs have been employed to investigate the reproducibility of the Florida Probe. 3 groups (each composed of 10 subjects) were selected for the study: healthy adults, gingivitis subjects, and periodontitis subjects. The 4 probing designs were as follows: (a) the probe tip was left in the sulcus between successive probings; (b) the probe tip was removed from the gingival margin between probings but the next probing followed immediately; (c) successive whole-mouth probings were interrupted by a 5-min interval and a mouthrinse; (d) there was a 4-week interval between each probing. 3 measurements were taken for each design. The main purpose of this study was to identify variance components in the attachment level variation. The maximum probing error standard deviation was found to be around 0.3 mm, which is considerably smaller than that found in most previous studies. The errors associated with the periodontal condition and probing effect were also estimated. The variance components obtained here can be used for determining the sample size in controlled clinical studies.

Effects of endothelin in portal hypertensive rats

1. Effects of endothelin-1 on systemic arterial blood pressure, heart rate and portal venous pressure were compared in normal Sprague-Dawley rats and rats with portal hypertension induced by CCl4 and partial portal vein ligation. 2. Endothelin-1 produced biphasic effects on systemic blood pressure and portal venous pressure in all three groups of rats. However, the magnitude of the changes in blood pressure was less in portal hypertensive rats. 3. The ability of endothelin-1 to increase the portal venous pressure was also significantly diminished in portal hypertensive rats. On the other hand, the initial decrease in portal pressure was augmented in rats with partial portal vein ligation, and disappeared at higher dosage in CCl4-treated rats. 4. In accordance with the pressure recording in vivo, the dose-response vasoconstrictive activity of endothelin-1 was significantly attenuated in the intrahepatic vasculature. 5. The plasma immunoreactive endothelin concentration was significantly higher (5.55 +/- 0.81 fmol/ml) in Sprague-Dawley rats than in CCl4-treated rats (2.83 +/- 0.56 fmol/ml) and rats with partial portal vein ligation (2.68 +/- 0.53 fmol/ml). 6. It was concluded that a lower plasma level of endothelin and a reduced vascular responsiveness may contribute, at least in part, to the hyperdynamics of portal hypertension.

Predictive power of various models for longitudinal attachment level change

Several statistical models that have been suggested in the periodontal literature for describing longitudinal attachment level changes, such as the gradual loss, single-burst, multiple-burst, and random walk models as well as other models introduced in this paper are compared by their power to predict future attachment loss. The data used in this analysis is from 1061 sites of 8 subjects, with moderate to severe periodontal disease, monitored monthly for about a year. This study found that none of the suggested models could significantly outperform the naïve mean predictor, which predicts the future attachment level from the past mean. It was also found that no single model, such as the burst, gradual, or random walk, together with measurement error can fully explain the variation in the data. These results indicate that in the course of one year, the attachment level change may not follow the same model. Consequently, a model that fits well to past data cannot be accurately extended to the future.

Lung deposits of lipiodol in normal and cirrhotic rats

The distribution of Lipiodol in the liver and lungs following arterial or portal injection was studied in normal (n = 55) and cirrhotic rats (n = 20). Using magnified xeroradiography and radioisotope labeled tracers, it was found that Lipiodol was deposited mainly in the liver and lung after either arterial or portal administration. In control rats after arterial injection, deposits in the lung peaked after 2 hours and gradually declined over 48 hours; whereas after portal injection, the deposit steadily increased for 48 hours. Twenty-five percent of cirrhotic rats demonstrated a Lipiodol-induced military pattern in the lung. An increased number of portosystemic shunts in cirrhotic rats was also noted. These results suggest that cirrhosis of the liver may be a potential risk factor for developing pulmonary complications after Lipiodol administration.

Evaluation of statistical methods for monitoring periodontal disease

Three methods for detecting the progression of periodontal disease based on the change in attachment level on teeth are compared from a statistical point of view. Regardless of gradual or burst disease progression theories, the regression method is found to be the most efficient way to detect changes. The exact false alarm rate is computed when the decision is based on the maximum regression coefficient at all sites during several visits.

cAMP and vascular action of endothelin

Endothelin, a potent vasoconstricting peptide, induced maximal contraction of the rat tail artery within 3 min of administration. Endothelin also caused a dose-dependent decrease in tissue levels of cAMP. Concentrations of cAMP decreased about 60% 1 min after endothelin (10(-8) M) administration, but returned to basal levels in 5 min. By contrast, tissue levels of cGMP were not changed by endothelin. Modulation of cAMP production may provide one mechanism for the vascular action of endothelin.

Correlation between low-temperature immunosuppression and the absence of unsaturated fatty acid synthesis in murine T cells

1. Studies were performed to determine if the inability of murine T cells to provide primary helper function at low temperature (27 degrees C) could be correlated with their inability to synthesize unsaturated fatty acids (UFAs). 2. In the absence of exogenous oleic acid (18:1), splenocytes responded to a T-dependent (TD) Ag (trinitrophenyl-keyhole limpet hemocyanin, TNP-KLH) at 37 degrees C but not at 27 degrees C. The addition of 150 microM 18:1 almost completely restored plaque-forming cell (PFC) responses to TNP-KLH at 27 degrees C but markedly suppressed PFC responses to the TD Ag at 37 degrees C. 3. During incubation at 27 degrees C, B cells converted 3- to 5-fold more stearic acid (18:0) to 18:1 and showed a greater accumulation of monounsaturated phospholipid molecular species than did T cells. 4. Following incubation in the presence of a rescuing dose of 18:1 (150 microM), both B and T cells accumulated large amounts of dioleoyl PC. 5. It is proposed that the absence of 18:1 synthesis in T cells is responsible for the unique low temperature susceptibility of this lymphocyte population.

Electrooculography and discriminant analysis in Duane's syndrome and sixth-cranial-nerve palsy

Eye-movement recordings may be helpful in the differentiation of Duane's syndrome from sixth-cranial-nerve palsy. Voluntary horizontal saccades were recorded and quantitated by electrooculography in 18 patients with unilateral type I Duane's syndrome and in 25 patients with sixth-nerve palsy. When ranges of abduction were matched, the peak velocities of abducting saccades in affected eyes were decreased equally in both groups. However, the peak velocities of adducting saccades in sound eyes were slowed in patients with Duane's syndrome. Because the standard deviations in saccadic velocities are large, computer-based, stepwise discriminant analyses were performed to identify the variables that proved to be useful in differentiating the two disorders. By entering these variables into the discriminant functions that were created, we could distinguish Duane's syndrome from sixth-nerve palsy in a statistically significant manner.

The hypotensive and negative chronotropic effects of dehydroevodiamine

The cardiovascular effects of dehydroevodiamine, an alkaloid isolated from Evodia rutaecarpa Jussieu, were studied in both in vivo and in vitro experiments. The in vivo experiments revealed that i.v. administration of dehydroevodiamine elicited a slight but significant reduction in blood pressure and a marked decrease in heart rate which was confirmed by an increased cycle length of the electrocardiogram. However, a hemodynamic experiment with microspheres showed that the total peripheral resistance was not altered by dehydroevodiamine. The blood flows of various organs were not significantly changed except those of kidney and skin, in which blood flow was decreased. In vitro, the spontaneously beating atria were significantly suppressed by dehydroevodiamine in a dose-dependent manner. These findings suggested an important effect of dehydroevodiamine in suppressing the heart, which may largely contribute to the hypotensive effect of this alkaloid. However, its vasodilator effect on hindquarter muscles cannot be neglected.

Identifying families at high risk of cardiovascular disease: alternative work site approaches

By examining coverage, concordance, and costs, this project evaluated four methods of cardiovascular disease (CVD) risk screening at a work site with 1821 central office employees of an energy company in Houston, Tex. Screening methods included a health risk appraisal mail questionnaire (HRA), an HRA plus brief physical assessment, an analysis of medical claims data, and an analysis of absenteeism data. Coverage ranged from 99% of employees for the absenteeism method to about 30% for the HRA method. Combining the first three screening methods, 18% of families had at least one member with a CVD or related diagnosis or one of four major CVD risk factors. The absenteeism method yielded 12.1% of the central office employees with 9 or more days absent. Although the absenteeism method identified high-cost families, only 9% had a heart disease or related diagnosis. This lack of concordance also occurs with other methods. For example, only 9.4% of families identified with the claims data were also identified by the HRA. Therefore, the methods identify different groups of high-risk families. Findings are discussed in relation to costs and other factors important to firms' selection of screening methods.

Effect of parathyroid hormone on portal pressure in portal hypertensive rats

Conflicting results have been common in the pharmacological treatments of portal hypertension. In an attempt to seek better management of portal hypertension, we studied the effect of the synthetic parathyroid hormone (PTH) fragment, [bPTH-(1-34)], in portal hypertensive rats (partial portal vein ligation). PTH, 10 U/kg, administered via the jugular vein resulted in a reduction of both mean arterial blood pressure (MAP) and portal pressure (PP) to a similar extent (18.9% and 16.9%, respectively). A higher dose (40 U/kg) of PTH lowered the PP by 27.8% and MAP by 43.2%. Hemodynamic experiments, performed with labelled microspheres, demonstrated that PTH decreased the blood flow of the splanchnic and hepatic portal collateral vascular beds. To determine whether there is a direct vasodilatory effect on the venous vasculature, the effect of PTH on the isolated portal vein was examined. PTH was capable of inhibiting both spontaneous and drug (methacholine 10(-7) mol/l or KCl 40 mmol/l-induced contraction in a dose-dependent manner. Therefore, it can be assumed that some of the effect of PTH on portal pressure is due to a selective effect on the portal vein.

Mechanisms of the vascular action of parathyroid hormone

The vasodilatory effect of parathyroid hormone (PTH) has been investigated repeatedly and confirmed over the past few years. The present study correlates the PTH-induced vasodilatory effect with the biochemical changes in cyclic AMP (cAMP) content and Ca++ uptake in the vascular tissue. Synthetic fragment bPTH-(1-34) (1.2 X 10(-7) M) significantly inhibited the contraction of the isolated tail artery of rat induced by KCl (30-80 mM). It also relaxed KCl (40 and 60 mM)-induced contractions in a concentration-dependent manner [2.7 X 10(-9) to 3.7 X 10(-8) M)]. In addition, the concentration-contraction curve of Ca (0.3-3.0 mM) was shifted to the right by PTH in 40 mM KCl Krebs-Henseleit solution. These suggest the blocking effects of PTH on Ca entry. This hypothesis was supported by a study in which PTH inhibited KCl-enhanced 45Ca uptake, an effect similar to that of D600. In the experiment with matched tissue, PTH increased tissue cAMP content whereas KCl did not. These suggest that the vascular actions of PTH may involve both cAMP and Ca entry blocking. It is important to know that PTH was capable of stimulating cAMP content in Ca-free medium, suggesting that the increase in cAMP level by PTH may not be secondary to the change in Ca++ uptake.

Castration may not affect the penile erection ability in terms of peripheral neurocavernous mechanism in dogs

The penile erection ability (PEA) was assessed in 27 dogs with intact orchids (Group I), seven dogs with bilateral orchidectomy for one month (Group II) and four dogs with bilateral orchidectomy for three months (Group III). PEA was indicated by the increase of the intracorporeal pressure (ICP) upon electrical stimulation of the cavernous nerves. PEA was significantly decreased in both orchidectomized groups. However, when reduction in the blood pressure was considered, the difference in PEA between Group I and the orchidectomized group was no longer significant. Before the orchidectomy, plasma testosterone level of 22 adult male dogs varied widely from 105 to 6302 pg./ml. At one or three months after the orchidectomy in 11 dogs, it decreased to a level below 100 pg./ml. There was no significant change in the body weight in the post orchidectomy period. These findings indicate that the castration and/or the resulting low plasma testosterone level does not directly affect PEA through the peripheral neural and cavernosal mechanism.

Effects of endothelin and vasopressin on portal pressure of rats

Endothelin is a vasoconstrictor peptide which has recently been isolated and sequenced from the vascular endothelial cells. It was reported to increase blood pressure in vivo and produce a prolonged contraction with a slow onset in vitro. The purpose of this study was to investigate whether endothelin can lower the portal pressure as another endogenous vasoconstriction peptidevasopressin (AVP) can. Heart rate, systemic blood pressure, portal pressure, and portal vein blood flow were measured. Effects of endothelin on these parameters were compared with those of AVP. Endothelin 10(-10) mol/Kg significantly decreased all of the parameters mentioned. At the higher dose (5 x 10(-10) mol/Kg), however, the portal pressure and blood pressure were increased and portal vein blood flow was unchanged. On the other hand, AVP decreased the portal pressure and portal vein blood flow but elevated the systemic blood pressure. In vitro experiments revealed that endothelin contracted both tail artery and portal vein of rat and vasopressin contracted only tail artery. We concluded that although both are endogenous vasoconstricting peptides, endothelin and AVP affect differently on arterial and venous vascular beds as well as on portal pressure.

Unsaturated fatty acids inhibit IL-2 production in thymus-dependent antibody responses in vitro

Albumin-complexed unsaturated fatty acids such as oleic acid (18:1) exerted a dose-dependent inhibitory effect on in vitro primary anti-TNP plaque-forming cell (PFC) responses to trinitrophenyl keyhole limpet haemocyanin (TNP-KLH), but did not affect primary PFC responses to trinitrophenyl lipopolysaccharide (TNP-LPS). The addition of 150 microM 18:1 at the initiation of thymus-dependent (T-D) antibody cultures inhibited the subsequent PFC response by 85%, and removal of the fatty acid after 24 hr did not reverse its inhibitory effect. By contrast, delaying the addition of 18:1 until 3 or 4 days after culture initiation abrogated its inhibitory effects. T-D antibody cultures displayed maximum production of interleukin-2 (IL-2) on the third day after culture initiation and a 24-hr exposure to 18:1 resulted in a dose-dependent inhibition of IL-2 production. Lastly, the addition of exogenous IL-2 reversed the inhibition of PFC responses in cultures transiently exposed to 18:1. These findings suggest that unsaturated fatty acids inhibit in vitro T-D PFC responses by selectively interfering with early stages of the antibody response, particularly those events leading to IL-2 production by T-helper cells.

Effect of calcium diet on the vascular reactivity of DOCA-salt hypertensive rats

It has been demonstrated that an increase in dietary calcium intake can lower the blood pressure of the hypertensives. We examined the effect of dietary calcium on blood pressure and vascular reactivity in DOCA-salt hypertensive rats. Blood pressure was significantly decreased after four weeks of calcium feeding. Nevertheless, the development of hypertension was not completely avoided. There was no difference between the calcium fed group and the control group in their response to NE, KCl and AVP in tail artery helical strips in normal calcium medium in vitro. However, the responses of these two groups to NE (10(-6) M) and AVP (10mU) were significantly different in Ca2+-free medium. Furthermore, the tail artery from Ca-fed group was less responsive to K+-induced relaxation. Since K+-induced relaxation has been applied to indicate the activity of Na+-K+ pump, we suggest that the activity of Na+-K+ pump may be involved and that the change in vascular reactivity to agonists might be rather insignificant in lowering the blood pressure of Ca-fed DOCA-salt hypertensive rats.

Local suppressive effect of clonidine on penile erection in the dog

Dogs, 8.5 to 10 kg. in weight, were anesthetized with sodium pentobarbital (35 mg./kg.), intraperitoneally. Penile erection as indicated by an increase in the intracorporal pressure (ICP-increase) was produced by electrical stimulation of the right cavernous nerves. Drugs were administered into the internal pudendal artery (IPA) and femoral vein. A low dose (0.2 to 0.4 microgram/kg.) of clonidine, an alpha 2 adrenoceptor agonist, which could not affect either ICP or systemic arterial pressure (SAP) through an intravenous route, did suppress the ICP-increase markedly via direct injection into the IPA which supplies the penile blood flow. By intra-IPA injection, yohimbine (2.5 micrograms/kg.), an alpha 2 adrenoceptor antagonist, remarkably restored the ICP to the erection state. By intravenous injection, clonidine at a dose of 1.6 to 3.2 micrograms/kg. also profoundly reduced the ICP-increase, but only negligibly lowered the SAP. The IPA blood flow (IPAF) decreased coincidentally when the ICP-increase was effectively reduced by either intravenous or intra-IPA injection of clonidine. These findings suggest clonidine could act locally in the penile structure to suppress penile erection, possibly resulting from a penile vasoconstriction involving alpha 2 adrenoceptor. Whether this vasoconstriction is caused by a direct alpha 2 stimulating effect on the vascular smooth muscle or by an alpha 2 presynaptic inhibition of the vasodilator nerve (cavernous nerve) endings has been discussed.

Parathyroid hormone and calcium entry blockade in a vascular tissue

The mechanism of the vasorelaxing action of a synthetic parathyroid hormone fragment, bPTH-(1-34), was studied. Rat tail artery helical strips were constricted in vitro with potassium chloride (6 x 10(-2) M), arginine vasopressin (2 mU/ml) or BAY-K-8644 (3 x 10(-7) M in the presence of 1.5 x 10(-2) M KCl). bPTH-(1-34) was able to relax the constricted tissue or to inhibit the constriction. All three constricting agents increased calcium uptake by the vascular tissue as determined by the measurement of the low-affinity lanthanum-resistant pool of calcium. Such increases in calcium uptake were significantly reduced by bPTH-(1-34). These data suggest that PTH may be a natural circulating hormone or chemical capable of inhibiting calcium entry in a vascular tissue.

Protein and metabolizable energy requirements of hand-fed squabs from hatching to 28 days of age

Incubator-hatched squabs were hand fed slurries containing 14% diet and 86% water by weight for the 1st 4 days, followed by 20% diet and 80% water for the next 2 to 3 days. From Days 7 to 28, the slurry contained 25% diet and 75% water. A diet containing about 61% isolated soybean protein, 8.9% soybean oil, 21.5% glucose, 4% CaHPO4.2H2O, and 1.3% CaCO3 supplemented with vitamins and trace elements supported the optimum growth of squabs for the first 7 days. It contained 3,675 kcal metabolizable energy (ME)/kg and 53.3% crude protein (CP). The composition of the optimum diet for feeding from Days 7 to 289 was as follows: corn starch, 58.37%; isolated soybean protein, 23.1%; cellulose, 8.0%; soybean oil, 3.0%; CaHPO4.2H2O, 3.0; methionine, .3%; CaCO3, 1.0; plus vitamins and trace minerals. This diet provided 3,200 kcal ME/kg and 20% CP.

Structure-activity relationship of parathyroid hormone: relative sensitivity of rabbit renal microvessel and tubule adenylate cyclases to oxidized PTH and PTH inhibitors

It has been shown previously that secondary structural changes of bPTH-(1-34) (synthetic amino-terminal (1-34) fragment of bovine parathyroid hormone), obtained by oxidation of the methionines 8 and 18, abolished its hypotensive but not its hypercalcemic action. Hence, it has been postulated that the various physiological effects of the hormone are mediated by different receptors that require different regions or configurations of the peptide. To further examine this hypothesis the relative sensitivity of the PTH-responsive adenylate cyclase of microvessels and tubules isolated from rabbit kidney cortex, to oxidized PTH and PTH inhibitors, was examined. In the presence of GTP, bPTH-(1-34) stimulated both microvessel and tubule adenylate cyclase in a dose-dependent fashion and with analogous affinities (ED50 = 52 nM in the microvessels and 85 nM in the tubules). Hydrogen peroxide treatment of bPTH-(1-34) resulted in the loss of the adenylate cyclase stimulating potency in the microvessels while there was substantial enzyme activation (ED50 = 900 nM) in the tubules. Oxidized PTH inhibited the untreated PTH-stimulated adenylate cyclase, suggesting that oxidized PTH still retains an affinity for vascular receptor sites. Similar treatment of the sulfur-free PTH analog [Nle8,18, Tyr34]bPTH-(1-34)NH2, where methionines have been replaced by norleucine, had little or no effect in both fractions. In the microvessels the synthetic PTH antagonist analogs [Nle8,18, Tyr34]bPTH-(3-34)NH2 and [Tyr34]bPTH-(7-34)NH2, strongly inhibited the adenylate cyclase responses to bPTH-(1-34). No inhibition was seen in the tubules with the same molar ratios of inhibitor to native PTH. Together, these results suggest strongly that the differences in the adenylate cyclase response to various PTH fragments most likely represent a difference in the structural requirements for PTH actions between microvessels and tubules.

Cyclic AMP and the vascular action of parathyroid hormone

The involvement of tissue cAMP in the vasodilating action of parathyroid hormone (PTH) was investigated. The bovine active fragment bPTH-(1-34) was used in all studies. In anesthetized dogs, theophylline, a phosphodiesterase inhibitor, potentiated the hypotensive action of bPTH-(1-34) at the dose of 1 microgram/kg. The potentiation was related to the dose of theophylline infused. In an in vitro rat tail artery helical strip assay, dibutyryl cAMP produced dose-related relaxation in arginine vasopressin (AVP) constricted blood vessels. bPTH-(1-34) also produced dose-related relaxation in the tail artery constricted by AVP. In the presence of isobutylmethylxanthine, another phosphodiesterase inhibitor, the bPTH-(1-34) dose--response curve was shifted to the left, indicating potentiation. Imidazole, which has phosphodiesterase stimulating activity, significantly decreased the in vitro vasorelaxing effect of bPTH-(1-34). In addition, bPTH-(1-34) increased significantly the rat tail artery cAMP content. b-PTH-(1-34) oxidized with hydrogen peroxide lost its vasorelaxing activity and was also ineffective in increasing the tail artery cAMP content. All these data strongly suggest that cAMP may be involved in eliciting the vasorelaxing action of bPTH-(1-34).

Correlation of structural changes in parathyroid hormone with its vascular action

The analysis of the spectrum of circular dichroism (CD) of methionine-oxidized bovine parathyroid hormone peptide, bPTH(1-34) revealed that approximately 43% of the orderly conformation (alpha-helix and beta-sheet) was converted into random coil structure. This peptide failed to elicit any hypotensive response in rats at any of the tested doses from 0.01 to 0.05 mg/ml. The blue shift of tryptophan fluorescence and the increase in the fluorescence intensity of the fluorescence probe 2-p-toluidinylnaphthalene-6-sulfonate (TNS) bound to the oxidized peptide indicated that the more hydrophobic environment was generated in the tryptophan domain as well as the molecule as a whole when the methionines in the peptide were oxidized. Modification of arginine with 1,2-cyclohexanedione (CHD) reduced 30% to 50% of the hypotensive action of the peptide hormone. Similar results in the increase of hydrophobicity of the arginine-modified peptide were also observed. These studies suggest that the conformational changes due to the methionine oxidation or arginine modification may be related to the inactivation of the vascular activity of bPTH(1-34).

Kinetics of membrane immunoglobulin capping on murine B lymphocytes. Effects of phospholipid fatty acid replacement

Detailed analyses regarding the effects of temperature and phospholipid fatty acid replacement on the capping of membrane immunoglobulin (mIg) have been performed using a recently described flow cytometric procedure (Cuchens, M. A., and Buttke, T. M. (1984) Cytometry 5, 601-609). Purified murine B cells were incubated for 12-20 h in the presence of bovine serum albumin-complexed 80 microM stearic (18:0), oleic (cis-18:1), or linoleic (cis, cis-18:2) free fatty acids. Unmodified and free fatty acid-treated cells were stained with fluorescein-conjugated rabbit anti-mouse Ig and subjected to pulse-shape (width) analyses to follow the kinetics of mIg capping. In both unmodified and free fatty acid-treated cells, capping of mIg occurred at all temperatures between 17 and 37 degrees C, but the rate of cap formation was temperature dependent. Arrhenius plots of mIg capping were linear, with activation energies ranging from 14 to 23 kcal/mol depending on the saturated/unsaturated fatty acid ratio of B cell phospholipids. Ligand-induced redistribution of mIg thus appears to be sensitive to changes in membrane acyl chain composition.

Hypotensive action of parathyroid hormone in chicken

In a recent series of studies, the hypotensive action of parathyroid hormone (PTH) was demonstrated in several vertebrate species. In mammals, the mechanism of this direct action on specific vascular beds was studied. An increase in intracellular cyclic AMP and an inhibition of entry of extracellular calcium into the vascular tissue was correlated with the vasorelaxing action of PTH. In the present report, PTH was found to relax chicken mesenteric vessels in vitro in the presence or absence of constriction with concentrated potassium chloride (KCl). PTH produced dose-related inhibition of the chicken vessel constricted with 10, 20, 40, or 60 mM KCl. Extracellular calcium-dependent constriction of the chicken mesenteric artery was also decreased by PTH. An inhibitory effect was also observed with D600, a known calcium-entry inhibitor, in the above in vitro test systems. The low affinity lanthanum-resistant pool of calcium, which supposedly reflects the rate of calcium entry into cells, was also decreased by PTH in the control or KCl-stimulated chicken mesenteric artery. These data suggest that PTH may produce vasorelaxation in chicken mesenteric artery by inhibition of calcium entry into cells. This vessel from the chicken seems to have a high turnover rate of calcium and may be a good model for studying the effects of substances on calcium entry in vascular smooth muscle.

Parathyroid hormone (PTH) fragments relax the guinea-pig trachea in vitro

Synthetic bovine parathyroid hormone fragment containing the N-terminal 1-34 amino acids (bPTH-(1-34) ) relaxed the guinea-pig trachea constricted with histamine in vitro. Peptides with bovine and human sequences purchased from Peninsula Laboratories and Beckman Bioproducts produced similar effects. Substitution of methionine in positions 8 and 18 by norleucine did not affect this property of bPTH-(1-34). However, when the methionines were oxidized by treating the peptide with hydrogen peroxide, the peptide could no longer produce relaxation in the trachea. Oxidation of the methionine-replaced analog did not affect the action of the peptide on the trachea. It seems that the methionines per se are not necessary, but once oxidized the conformation of the molecule may be sufficiently altered to affect its ability to relax the trachea. While propranolol can block the relaxing action of isoproterenol, this blocking agent produces no inhibition of the bPTH-(1-34) effect. This action of PTH on the trachea may be related to cAMP because isobutyryl-methylxanthine, a phosphodiesterase inhibitor, potentiates and imidazole, a phosphodiesterase stimulator, inhibits the trachea relaxing action of bPTH-(1-34).

Chronotropic actions of bPTH-(1-34) in the right atrium of the rat

Bovine parathyroid hormone and its N-terminal (1-34) peptide fragment (bPTH-(1-34] are known to possess direct hypotensive activity in the rat. The purpose of the present study was to determine if bPTH-(1-34) possessed a direct chronotropic action as well. In vivo studies revealed that bPTH-(1-34) did produce a chronotropic effect in the rat comprising both a direct component as well as a reflex tachycardia related to its hypotensive actions. In vitro studies of isolated right atria indicated that while bPTH-(1-34) had no positive inotropic effect, it did produce significant chronotropic effects which were direct and dose-dependent. The potency of bPTH-(1-34) was found to be similar to that of isoproterenol, however, it was only one-third as effective as isoproterenol in maximally increasing atrial rate. A slight but significant increase in atrial cyclic AMP was generated prior to the chronotropic actions of bPTH-(1-34).

Structure activity relationship of parathyroid hormone: separation of the hypotensive and the hypercalcemic properties

The present study was conducted to show that the hypercalcemic and the vascular relaxing activities of PTH are two separable properties. During the hypotensive action of the synthetic fragment bovine (b) PTH-(1-34), plasma calcium levels were not significantly changed. Mild oxidation with hydrogen peroxide abolished the hypotensive and hypercalcemic actions of bPTH-(1-84). However, the same treatment on bPTH-(1-34) abolished only the hypotensive and not the hypercalcemic action. Analysis of the amino acid composition revealed only the oxidation of the methionines to methionine sulfoxides. The other amino acids remained unchanged. In addition, the analog with methionines replaced by norleucine, [Nle8,Nle18,Tyr34]bPTH-(1-34), was active in all the vascular assays, and these activities were unaffected by hydrogen peroxide treatment of the molecule. Perhaps the methionine sulfoxides in the hydrogen peroxide-treated bPTH-(1-34) affected the changes of the molecule in such a manner that the part of the molecule for the vascular action but not that for the hypercalcemic action was no longer accessible to the receptors of the target organs. The hypotensive pentapeptide, bPTH-(24-28), was not active in the hypercalcemic assay. All these data are consistent with our hypothesis that the vascular relaxing and the hypercalcemic actions of PTH are two separate properties of the molecule.

The effect of the propagation coefficient on size distribution in micellar systems

In this study the effect of the propagation coefficient on the molar distribution function in a modified shell model for micellar systems was examined. The sharpness of the micelle size distribution boundary was found to depend less on the degree of polymerization, n, than on the propagation coefficient, P. Although Kegeles (J. Phys. Chem. 83 (1979) 1728) has reported a marked sharpening of the distribution boundary when P = 2.0. we found the boundary to be fairly broad at this point. However, as values of the propagation coefficient were increased from 3 to 10, the micelle distribution boundary became increasingly sharp. The possibility of such a change in the reaction boundary arising from a structural transition, accompanied by a change in the rate of dissociation of monomer from the shell, is also discussed.

Structure and vascular activity relationship of parathyroid hormone and some hypotensive peptides

The synthetic fragment of bovine PTH [bPTH-(1-34)] had direct vasodilatory action in the coronary, renal, hepatic and some visceral vascular beds. The vascular action of bPTH-(1-34) was separable from its hypercalcemic action. We attempted to identify the amino acid sequence responsible for this vascular action. The methionines in positions 8 and 18 were not necessary for vascular relaxation since [Nle8, Nle18, Tyr34]-bPTH-(1-34) was active. However, when these methionine residues were oxidized, the vascular action of this peptide disappeared. This would suggest conformational changes of this oxidized peptide, resulting in loss of activity. Adjacent basic amino acids in positions 25, 26 and 27 may play an important role in the hypotensive action of peptides. Other hypotensive peptides such as neurotensin, xenopsin and VIP which also possess adjacent basic amino acids but are not known to be vasoactive were also hypotensive in our assays.

Hypotensive action of synthetic fragments of parathyroid hormone

Parathyroid hormone (PTH) and its N-terminal 1-34 fragment were shown to be hypotensive in dogs. In this study, synthetic bovine PTH fragments containing the N-terminal amino acids 1-34, 24-34, 24-28 and 25-27 [bPTH-(1-34), bPTH-(24-34), bPTH-(24-28) and bPTH-(24-27)] were synthesized and tested for hypotensive activity in dogs. bPTH-(1-34) is the most potent of these. The tripeptide is ineffective at doses as high as 2 mg/kg. bPTH-(24-34) and bPTH-(24-28) exhibited hypotensive activity but were less effective than bPTH-(1-34). A decrease in chain length decreased the hypotensive activity. The maximum response produced by bPTH-(1-34) was greater than that of either bPTH-(24-34) or bPTH-(24-28). The maximum responses, however, of bPTH-(24-34) and bPTH-(24-28) were similar. Another striking difference between bPTH-(1-34) and the other two effective fragments was the duration of action. Whereas the action of bPTH-(1-34) at ED50 lasted for up to 6 min the action of bPTH-(24-34) and bPTH-(24-28) lasted for less than 1 min. The hypotensive effect of these three bPTH fragments was not affected by propranolol, phentolamine, atropine, promethazine or cimetidine. In the perfused rat hindlimb, bPTH-(24-28) produced log dose-related sustained vasodilation.

Lack of histamine involvement in parathyroid hormone hypotensive action

Promethazine and cimetidine blocked the hypotensive actions of 2-pyridylethylamine, and H1 agonist and dimaprit, an H2 agonist, respectively, but not that of bovine parathyroid hormone fragment [bPTH-(1-34)]. Rats were treated repeatedly with the histamine releaser, compound 48/80, until the release could no longer produce a decrease in blood pressure. The hypotensive action of bPTH-(1-34) could still be seen. Rats with histamine partially depleted with one injection of compound 48/80 were injected with cimetidine and pyrilamine, and H1 antagonist, which together blocked the hypotensive action of subsequent injections of compound 48/80, but not that of bPTH-(1-34). These data suggest that the vasodilatory action of bPTH-(1-34) does not involve the release or action of histamine.

Scanning molecular sieve chromatography of interacting protein systems. III. Effect of kinetic parameters on the large zone boundary profiles for local equilibration between mobile and stationary phases

Large zone reaction boundary profiles for molecular sieve chromatography as affected by kinetic parameters have been simulated for local equilibration between the mobile and stationary phases. Our studies of monomer-dimer and monomer-tetramer systems indicate that in a slowly equilibrating system, the kinetic controls operating between the mobile and stationary phases contribute most significantly to the overall boundary profile. In a rapidly equilibrating system, however, the kinetic parameters kij and kji operating in the mobile phase are the principal determinants of the reaction boundary, while the kinetic effects of kii and k-ii between the mobile and stationary phases are minimal.

Scanning molecular sieve chromatography of interacting protein systems. Simulation of large zone behavior for self-associating solutes undergoing rapid chemical equilibration under kinetic control

Theoretical large zone reaction boundaries for molecular sieve chromatography have been simulated by computer for a self-associating solute undergoing rapid chemical equilibration under kinetic control. These patterns show that the kinetically-controlled reaction rate between the mobile and stationary phases is the principal determinant of the elution boundary profile in molecular sieve chromatography. The overall chemical reaction rate in the mobile phase was found to have a much greater role in a rapidly equilibrating system than did the effect of axial dispersion within the gel matrix.

Multiple leukocyte abnormalities in chronic granulomatous disease: a familial study

A variety of leukocyte enzyme activities were studied in an 11-year-old female with chronic granulomatous disease (CGD) and several members of her family. Leukocyte glucose-6-phosphate dehydrogenase (G-6-PD) activity was 17 nmol/min/mg protein in the patient; two brothers with symptoms of recurrent bacterial infections have G-6-PD activities of 58 and 37 nmol/min/mg protein; the activites of this enzyme in both parents, maternal grandmother, and one additional brother were within normal limits. Storage at 4 degrees or heating at 37 degrees over a 120-min period revealed a marked lability of G-6-PD activity in the patient's cells which could not be stabilized by the addition of NADP and 2-mercaptoethanol; this lability was not seen in other family members tested. Activities of leukocyte glutathione reductase were reduced in both parents and the two affected male siblings with values of 18, 23, 23, and 24 nmol/min/mg protein, respectively. Activities of leukocyte glutathione peroxidase were reduced in all of the immediate family members tested, with values ranging from 11.2 to 43 nmol/min/mg protein; the activity of this enzyme in the patient was 38.5. Leukocyte NADP content in the patient, father, and two affected male siblings were 16.5, 23.4, 22.2, and 28.2 nmol/15 min/10(7) leukocytes, respectively.

Scanning molecular sieve chromatography of interacting protein systems. III. Effect of kinetic parameters on the large zone boundary profiles for local equilibration between mobile and stationary phases

Large zone reaction boundary profiles for molecular sieve chromatography as affected by kinetic parameters have been simulated for local equilibration between the mobile and stationary phases. Our studies of monomer-dimer and monomer-tetramer systems indicate that in a slowly equilibrating system, the kinetic controls operating between the mobile and stationary phases contribute most significantly to the overall boundary profile. In a rapidly equilibrating system, however, the kinetic parameters k(ij) and k(ji) operating in the mobile phase are the principal determinants of the reaction boundary, while the kinetic effects of k(ii) and k-(ii) between the mobile and stationary phases are minimal.