Spontaneous noncardiac chest pain. Evaluation by 24-hour ambulatory esophageal motility and pH monitoring

Noncardiac chest pain can be a diagnostic dilemma because patients rarely experience spontaneous chest pain in the laboratory. Therefore, we studied 24 patients with chronic, daily, substernal chest pain with a prototype 24-h ambulatory esophageal motility and pH system. Spontaneous chest pain episodes were correlated with pH less than 4 and abnormal motility changes (mean amplitude and duration, maximum amplitude and duration, or percentage of abnormal peristalsis) defined as exceeding the patient's normal esophageal motility pattern. Twenty-two patients experienced a total of 92 spontaneous chest pain episodes. Eleven chest pain episodes (12%) occurred during abnormal motility, whereas 18 episodes (20%) were associated with pH less than 4 and four episodes (4%) had both abnormalities. The majority of chest pain episodes, 59 events (64%), did not have any association with motility or pH. Abnormal maximum duration and amplitude were the motility changes most frequently associated with chest pain. Overall, 13 of 22 patients (59%) had at least one chest pain episode correlating with abnormal motility or pH (range 33%-100%). Therefore, we conclude that ambulatory esophageal motility and pH monitoring is useful in the evaluation of noncardiac chest pain. pH abnormalities (20%) are more commonly associated with chest pain than motility abnormalities (12%). However, the majority of chest pain episodes (64%) did not correlate with either abnormality and may be the result of lowered esophageal pain threshold for distention, i.e., the "irritable esophagus."

Immune and bone properties of chicks consuming corn contaminated with a Fusarium that induces dyschondroplasia

A study was conducted to contrast the dyschondroplasia-inducing capability of several species of Fusarium with that of the natural fungi found in poultry diets and litter. Day-old broiler chicks were fed pure corn cultures of specific fungal isolates for 3 weeks. Humoral immunity to sheep red blood cells (SRBC), body weight, valgus and varus leg deformities, incidence of dyschondroplasia, and mechanical properties of the tibiotarsi were examined. F. equiseti #15 was the only fungal isolate to induce dyschondroplasia to any significant degree, which confirmed previous work in Minnesota. This isolate also suppressed growth rate and humoral immunity, although dyschondroplasia sometimes did occur without associated immunosuppression and growth depression. Bone strength of the tibiotarsal diaphysis was normal, and gross lesions of valgus and varus leg deformities did not appear to be related to the incidence of dyschondroplasia in the 3-week-old chicks.

Evidence that heme d1 is a 1,3-porphyrindione

Heme d1 is the noncovalently associated heme prosthetic group of the bacterial nitrite reductase known as cytochrome cd1. Additional evidence has been obtained in support of a dioxoisobacteriochlorin, or 1,3-porphyrindione, skeleton for this heme. The new data include the natural abundance 13C NMR spectrum of the free base methyl ester derivative of d1, mass spectrometric determinations of the molecular mass of the free base methyl ester and the Cu and the Zn chelates, visible and 1H NMR spectral comparisons between d1 and synthetic porphyrindione model compounds, and the isolation and characterization of several byproducts formed during the purification of the free base methyl ester of d1. The accumulated evidence strongly supports the following structure for the skeleton of d1: 1-oxo-2-methyl-2'-acetyl-3-oxo-4-methyl-4'-acetyl-5-methyl-6-acrylyl+ ++-7- propionyl-8-methylporphyrin.

The porphinedione structure of heme d1. Synthesis and spectral properties of model compounds of the prosthetic group of dissimilatory nitrite reductase

In an attempt to verify the recent proposal that the heme d1 prosthetic group isolated from cytochrome cd1 is not a chlorin, but a dioxo-isobacteriochlorin (Chang, C. K. (1985) J. Biol. Chem. 260, 9520-9522), a model dioxo-isobacteriochlorin has been synthesized possessing a pi-electron system exactly identical to that as proposed. The presence of an acrylic acid substituent strongly perturbs the absorption spectrum of the chromophore and produces a visible spectrum virtually indistinguishable from that of the iron-free heme d1. Based on this finding, buttressed by additional spectral correspondence between the model iron heme and heme d1, we conclude that the proposed diketo ring structure is indeed correct, and the trivial names "dioneheme" and "acryloporphyrindione" are suggested for heme d1 and the demetallated macrocycle, respectively.

Chemical softening and wear of dental composites

The purpose of this work was to determine the influence of chemical food-simulating liquids on the wear of various commercial dental composite restoratives. In many cases, pre-conditioning the restoratives in these liquids for one week produced swelling of the polymer matrix and considerable surface damage. The resulting degradation reduced the hardness and enhanced the wear as measured by a pin-and-disc apparatus. Four kinds of commercial composites were investigated: a conventional quartz-filled, a strontium-glass-filled, a visible-light-activated, and a microfilled composite. The liquids employed were heptane and several aqueous solutions of ethanol with solubility parameters, delta, ranging from delta = 1.5 to 4.8 X 10(4) J1/2m-3/2. With all restoratives, the decline in hardness during pre-conditioning maximized at about delta = 3 X 10(4), which corresponds to a 75% ethanol solution. The wear behavior was considerably more complicated and variable, as discussed in the text. For the most part, the increase in wear rate from pre-conditioning corresponded to the fall in hardness. A notable exception was for the strontium-glass-filled composite pre-conditioned in pure water. Here the wear was enhanced considerably, with no decrease in hardness. In this case, the degradation mode is assumed to be different from the others in that it is attributed to stress corrosion of the glass filler.

Effect of maturation and age on lymphocyte proliferation induced by A23187 through an interleukin-independent pathway

Lymphocyte proliferation induced by lectins declines drastically with age. It has been suggested that the reduction of interleukin production by lymphocytes from old individuals is responsible for the decline in proliferation. In this study, lymphocyte proliferation was stimulated by the calcium ionophore, A23187. A23187 induced the proliferation of spleen lymphocytes from rats through an interleukin-independent pathway; depletion of spleen lymphocytes of macrophages, addition of exogenous interleukin 2 (IL 2), and addition of anti-IL 2 monoclonal antibodies had no effect on the proliferation stimulated by A23187. Spleen lymphocytes from male Fischer F344 male rats of 5, 13, 22, and 30 months of age were stimulated with either concanavalin A (Con A) or A23187. A 50% decrease in Con A- and A23187-induced proliferation was observed between 5 months and 13 months of age. A23187-induced proliferation decreased only slightly between 13 months and 30 months of age (14%), while Con A-induced proliferation decreased by 34%. This is the first report to show that the induction of lymphocyte proliferation through an interleukin-independent pathway decreases with increasing age. In addition, these results suggest that a decrease in the responsiveness of cells to calcium ions might be an important factor in the age-related decline in lymphocyte proliferation.

Twenty-four-hour profiles of prolactin and testosterone in ram lambs exposed to skeleton photoperiods consisting of various light pulses

Individual groups of 6 ram lambs were housed within a controlled environment and exposed to one of 6 photoperiod schedules. Groups I and II received 8 (short day) or 16 (long day) h of continuous light, respectively; Groups III, IV and V were exposed to asymmetrical skeleton photoperiods consisting of a main light period of 7 h followed 9 h later by a light pulse of 1 h, 15 min or 1 min duration, respectively, and Group VI was exposed to a symmetrical skeleton photoperiod consisting of two 1-h light pulses positioned 16 h apart. After 4 weeks of treatment serum concentrations of prolactin and testosterone were measured over 24 h. Long-day responses characteristic of the 16L:8D photoperiod (i.e. elevated prolactin and reduced testosterone) were obtained in each of the asymmetric light-pulse treatment groups, but whereas prolactin was elevated over the full 24 h in lambs exposed to 16L:8D, two prominent nocturnal prolactin releases were largely responsible for the high 24-h mean prolactin values in Groups III, IV and V. Reduced serum testosterone in these same groups could not be attributed to a diurnal pattern of secretion but was associated with an overall decrease in testosterone pulse frequency. Prolactin and testosterone levels in Group IV were intermediate between those observed in lambs exposed to 8 or 16 h of light. In summary, light pulses of short duration (1 min) positioned at 17 h after dawn can produce endocrine changes in lambs similar to those observed in lambs exposed to 16 h of continuous light.

Vasopressin release from individually superfused neurohypophyses decreases in aged rats

We studied the effect of aging on vasopressin (VP) release from isolated neurohypophyses (NH) individually superfused with synthetic medium TC 199 with Hanks' salts. The superfusion technique is described in detail. Male Fisher 344 rats 2 months (young, n = 17), 12 months (adult, n = 14) and 30 months (old, n = 17) of age were used. VP was measured by radioimmunoassay (RIA). The age-related VP release was analyzed as follows: initial traumatic release, basal release, VP release evoked by electrical stimulation (10-second trains every 20 s of matched biphasic stimuli, 0.2 ms width, 8 mA, 30 Hz), by chemical stimulation (56 mM K+) and total release for the entire superfusion period. When VP release was expressed per milligram NH, it was significantly lower under all conditions in the old rats than in the young ones. In the adult rats, traumatic, basal and total release values were similar to those of the young rats, whereas their responses to chemical and electrical stimulation were similar to those of old rats. Residual VP content expressed per whole NH was significantly higher in the old and adult rats, reflecting a larger glandular size, but when expressed per milligram NH tissue, it was low in the old rats. The percent of VP released during the entire superfusion period relative to the residual VP content was significantly lower in the old than in the young and adult rats. The magnitude of the maximal VP release exceeding the basal release, in response to electrical and chemical stimulation, was similar in young and old rats. However, in the adult rats it was significantly lower than in both the young and old following chemical stimulation. A significantly larger number of old and adult NHs exhibited a more delayed response to chemical, but not to electrical stimulation, than did the young NHs. These data demonstrate an age-related decrease in VP release in Fisher 344 rats. Since the traumatic and basal VP release in the adult rats is similar to the release in the young rats, while the stimulated release in the adult rats resembles the response of the old animals, the results suggest that an impairment of stimulated VP release occurs at an earlier stage of the aging process than does an impairment of spontaneous (traumatic and basal) release.

Subsurface damage layer of in vivo worn dental composite restorations

Dental composite restorations have been examined using a silver staining method to elucidate in vivo wear mechanisms. Emphasis was placed on examination of material immediately beneath the wearing surfaces. Several in vitro tests were also investigated for their ability to generate in vivo-like surface defects. For all the clinically worn composite restorations, a porous layer has been observed beneath those surfaces exposed to the oral environment. A laboratory test using certain substances to simulate the oral environmental effects can reproduce this porous layer. These results suggest that the in vivo wear process of dental composites is one accelerated by environmental softening of the composites.

The effect of microwave irradiation on vasopressin in plasma and hypothalamo-neurohypophyseal system

Radioimmunoreactive vasopressin was measured in plasma, neurohypophysis and hypothalamus of the rats after different procedures of killing: a) microwave irradiation; b) decapitation; c) decapitation following a stress induced by immobilization in a restrainer. Vasopressin content in the neurohypophysis and hypothalamus was much lower in microwave irradiated than in both decapitated and stressed decapitated rats. In addition, the data from microwave technique were inconsistent with a large scatter. Plasma vasopressin concentration was elevated in both the microwave irradiated and stressed decapitated rats, demonstrating that restraining of the animals induced an excessive stress. Microwave irradiation technique including the necessary manipulation of the animal proved to be less suitable than decapitation technique for the measurement of vasopressin. It is likely that vasopressin in the hypothalamus and neurohypophysis is relatively resistant against post-mortem proteolysis.

Detecting margin leakage of dental composite restorations

The degree of microleakage between a restoration and the cavity wall is difficult to quantify objectively. A silver-staining method is used and compared to the radioisotope method with results that indicate a superior definition and more accurate evaluation of microleakage. In addition to the accuracy, two advantages are presented: (1) scoring of the leakage can be refined and divided into more precise numbers, and (2) teeth can be observed directly in a microscope without resorting to the indirect interpretation of film or photograph.

The effect of aging on vasopressin system in Fisher 344 rats

Vasopressin (VP) was measured by RIA in the plasma, neurohypophysis (NH) and hypothalamus (HT) of young (2 months), adult (12 months) and old (30 months) male Fisher 344 rats, ten of each age. Plasma VP concentration was significantly lower in old compared to adult and to young rats. VP content in the NH expressed per mg weight was similar in all three groups, while the hypothalamic VP content was decreased in the aged rats. This suggests that reduced synthesis and release and/or increased degradation of VP occurs in aged rats. These data are in an agreement with our previous results obtained with Sprague-Dawley rats indicating that these differences are not strain-related. In a pilot experiment, we further studied VP release from isolated perifused NH of young and old rats. Two glands of each age were simultaneously perifused in individual microchambers with medium TC 199 and subsequently stimulated by Locke's medium containing 56 mM K+. Both, the initial and the basal VP release from the NH of the old rats, as well as the response to high K+, were about a half that of the young rats. Thus, a decreased VP release may contribute to the findings of lower plasma VP concentration in aged rats.

Influence of chemicals on wear of dental composites

The wear resistance of a commercial dental restorative composite exposed to different chemicals was measured with a pin-disc apparatus. The initial wear rate increased dramatically once the composite had been immersed in chemicals known to soften the cross-linked matrix material, which is a copolymer derived from BIS-GMA and diluent monomer. The increase of wear rate in a chemically softened composite was found to persist over a depth beyond 160 μm for specimens immersed over two wk prior to wear testing.

Relationship between subsurface damage and wear of dental restorative composites

Pin and disc wear measurements were made on a commercial dental composite over a stress range from 2.5 to 20 MPa. The wear rates were found to increase suddenly during wear at times which tended to decrease with increasing stress. The results are interpreted in terms of wear mode conversion which results from the build-up of subsurface damage during wear. Micrographs showing damaged layers are compared with those from restorations worn in vivo.

A silver staining technique for investigating wear of restorative dental composites

A silver staining technique was developed to demonstrate microdefects in dental restorative composites. Fine silver particles were preferentially introduced into the damaged region to provide optical contrast between the damaged and the undamaged regions. The amount of silver deposition determined with an electron probe microanalyzer, provided an indication of the extent of damage within the dental composites. Examples to demonstrate this technique were given with one clinically worn dental composite restoration and one in vitro worn composite sample.

Purification of Torpedo californica post-synaptic membranes and fractionation of their constituent proteins

A rapid methof for preparation of membrane fractions highly enriched in nicotinic acetylcholine receptor from Torpedo californica electroplax is described. The major step in this purification involves sucrose-density-gradient centrifugation in a reorienting rotor. Further purification of these membranes can be achieved by selective extraction of proteins by use of alkaline pH or by treatment with solutions of lithium di-idosalicylate. The alkali-treated membranes retain functional characteristics of the untreated membranes and in addition contain essentially only the four polypeptides (mol.wts. 40000, 50000, 60000 and 65000) characteristic of the receptor purified by affinity chromatography. Dissolution of the purified membranes or of the alkali-treated purified membranes in sodium cholate solution followed by sucrose-density-gradient centrifugation in the same detergent solution yields solubilized receptor preparations comparable with the most highly purified protein obtained by affinity-chromatographic procedures.

Seasonal variations in vasopressin secretion in rats

Plasma vasopressin concentrations and vasopressin content in neurohypophysis in rats show seasonal variations; namely, high in summer and low in winter.

Probabilistic Aspects of Designing with Ceramics

The paper reviews the design methodology for brittle materials which is being developed under the Ford/ARPA contract. Theoretical aspects of designing with high-temperature ceramics are discussed and demonstrated on a turbine rotor system. Statistical treatment of brittle behavior, based on Weibull’s model, is reviewed and relations for predicting probability of failure and material strength requirements for complex ceramic structures are presented. Reliability considerations, uncertainty of predictions, and need for proof testing are discussed. Similarly, a probabilistic treatment of time to failure of a typical turbine structure in the presence of slow crack growth is presented using fracture mechanics and Weibull relations.

Effect of insulin, glucose, and controlled diabetes mellitus on human jejunal function

The effects of serum insulin concentration, serum glucose concentration, and of insulin-dependent diabetes mellitus on human jejunal glucose, Na, and H2O absorption were assessed. Triple-lumen perfusion studies were carried out in 20 nondiabetic and 9 insulin-requiring diabetic male volunteers. In seven normal subjects, sequential elevation of serum insulin concentrations from 20 muU/ml to 50 and 100 muU/ml for 2 h each, with maintenance of constant serum glucose levels, failed to significantly alter glucose, Na, and H2O absorption. Absorption of glucose, Na, and H2O was similar when the serum glucose concentration was maintained at 125 and at 250 mg/100 ml. Glucose absorption results during 26 perfusion studies in 20 control subjects were compared with results obtained during 20 perfusion studies in 9 diabetic subjects. Glucose concentrations in isotonic perfusates were 25, 40, or 75 mM. Na and H2O absorption rates were similar in both groups. Regression lines relating glucose load or geometric mean study segment glucose concentration to glucose absorption were also comparable. These results indicate that insulin-requiring diabetics absorb glucose, Na, and H2O normally.

Radionuclide demonstration of small-bowel anatomy in the afferent-loop syndrome: case report

Radionuclide imaging with I-131 rose bengal and orally administered Tc-99m colloid was successfully used to show the presence of an afferent loop that was not visualized by radiographic, endoscopic, or ultrasonic procedures.