Characteristic X-ray Production in Thin Crystals

The dependence of the characteristic X-ray production on electron beam orientation is studied using very thin epitaxially grown single crystals. In crystals of Ag and Pd of thickness ~100 Å the L shell yield can change by more than a factor of 2 for small changes in orientation near the [111] direction. Theoretical analysis of the results shows that the different Bloch waves do not produce X-rays independently but that interference effects occur. The significance of these observations is discussed.

THE ROLE OF CARBONIC ANHYDRASE IN CERTAIN IONIC EXCHANGES INVOLVING THE ERYTHROCYTE

1. The acceleration by bicarbonates of the swelling and hemolysis of erythrocytes in solutions of ammonium salts, first reported by Ørskov, is strikingly dependent upon carbonic anhydrase, being almost abolished by inhibitors of this enzyme such as KCN and sulfanilamide, and under suitable conditions being enhanced by its addition to the external solution. This behavior gives support to the theory of "catalyzed diffusion" as an explanation of the Ørskov effect. 2. The inhibitory effects of both sulfanilamide and KCN seem to be capable of complete reversal on washing the erythrocytes in isotonic salt solutions. The full effect of KCN appears almost instantly; that of sulfanilamide requires a period measured in seconds, or possibly even in minutes, to reach its maximum, the delay presumably being due to the slower penetration of the erythrocyte by this substance. Under favorable conditions the effect of concentrations of sulfanilamide of a few hundredths of a milligram per cent can be demonstrated. No similar effects have been obtained with sulfapyridine. 3. Bicarbonates also have a "catalytic" effect on the response of the internal pH of erythrocytes to changes in that of their surroundings. The resulting volume changes of the cell, which otherwise frequently require many minutes for their completion, may take place within a few seconds in the presence of low concentrations of bicarbonates. At a given pH value the effect of the latter substances is chiefly on the rate of the change and only to a minor extent on its magnitude. It may be further accelerated under appropriate conditions by the addition to the cell suspension of carbonic anhydrase, and can be almost abolished by KCN and by sulfanilamide. 4. Volume changes of erythrocytes associated with exchanges of Cl' for SO₄'' ions are greatly accelerated by low concentrations of bicarbonates, this effect being likewise dependent upon carbonic anhydrase. There is some evidence that in this case the exchange takes place, at least in part, in two steps: Cl' for HCO₃' and HCO₃' for SO₄''.

THE INFLUENCE OF AMMONIUM SALTS ON CELL REACTION

1. It may be shown by means of cells of the flowers of a hybrid Rhododendron which contain a natural indicator, by means of starfish eggs stained with neutral red, and by means of an "artificial cell" in which living frog's skin is employed that increased intracellular alkalinity may be brought about by solutions of a decidedly acid reaction which contain ammonium salts. 2. These results are analogous to those previously obtained with the CO(2)-bicarbonate system, and depend on the facts: (a) that NH(4)OH is sufficiently weak as a base to permit a certain degree of hydrolysis of its salts; and (b) that living cells are freely permeable to NH(4)OH (or NH(3)?) and not to mineral and many organic acids, and presumably not at least to the same extent to ammonium salts as such.

Quality of life after severe bacterial peritonitis and infected necrotizing pancreatitis treated with open management of the abdomen and planned re-operations

OBJECTIVE

To determine quality of life after severe bacterial peritonitis and infected necrotizing pancreatitis treated with open management of the abdomen and planned re-operations.

DESIGN

Retrospective chart review.

SETTING

University hospital intensive care unit, general wards, and outpatient department.

PATIENTS

Forty-one patients who survived severe bacterial peritonitis and infected necrotizing pancreatitis treated with open management of the abdomen and planned re-operations.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Over a period of 7 yrs, 95 patients underwent open management of the abdomen and planned re-operations for severe bacterial peritonitis and infected necrotizing pancreatitis. Thirty-nine patients died during the initial intensive care unit stay and 12 as a result of nonperitonitis-related systemic diseases after discharge. Four patients were lost or excluded from final analysis. Long-term morbidity and quality of life using Karnofsky and Rankin scores at discharge and at follow-up at least 1 yr after discharge (mean: 4 yrs) and the Sickness Impact Profile (SIP) were determined. The remaining 41 patients reviewed showed significant long-term morbidity, including dysfunction of the abdominal wall resulting from herniation, persistent polyneuropathy, and mental disorders needing psychiatric support. Patients having persistent polyneuropathy and, to a lesser extent, mental disorders, showed significantly lower Karnofsky, higher Rankin, and higher SIP scores. After discharge, performance status of patients improved significantly, as shown by higher Karnofsky and lower Rankin scores, and, because Karnofsky and Rankin scores are closely related to SIP scores, higher SIP scores. Especially in measuring quality of life in terms of social and role management, assessment of the SIP proved to have additional value.

CONCLUSIONS

About three-quarters of patients who survive open management of the abdomen and planned re-operations for severe bacterial peritonitis and infected necrotizing pancreatitis regain a good quality of life. Some patients, especially those who suffer from persistent polyneuropathy and mental disorders, show restrictions in daily life.

Glutamate transport in Rhodobacter sphaeroides is mediated by a novel binding protein-dependent secondary transport system

Growth of a glutamate transport-deficient mutant of Rhodobacter sphaeroides on glutamate as sole carbon and nitrogen source can be restored by the addition of millimolar amounts of Na+. Uptake of glutamate (Kt of 0.2 microM) by the mutant strictly requires Na+ (K(m) of 25 mM) and is inhibited by ionophores that collapse the proton motive force (pmf). The activity is osmotic-shock-sensitive and can be restored in spheroplasts by the addition of osmotic shock fluid. Transport of glutamate is also observed in membrane vesicles when Na+, a proton motive force, and purified glutamate binding protein are present. Both transport and binding is highly specific for glutamate. The Na(+)-dependent glutamate transporter of Rb. sphaeroides is an example of a secondary transport system that requires a periplasmic binding protein and may define a new family of bacterial transport proteins.

Expression of the gltP gene of Escherichia coli in a glutamate transport-deficient mutant of Rhodobacter sphaeroides restores chemotaxis to glutamate

Rhodobacter sphaeroides is chemotactic to glutamate and most other amino acids. In Escherichia coli, chemotaxis involves a membrane-bound sensor that either binds the amino acid directly or interacts with the binding protein loaded with the amino acid. In R. sphaeroides, chemotaxis is thought to require both the uptake and the metabolism of the amino acid. Glutamate is accumulated by the cells via a binding protein-dependent system. To determine the role of the binding protein and transport in glutamate taxis, mutants were created by Tn5 insertion mutagenesis and selected for growth in the presence of the toxic glutamine analogue gamma-glutamyl-hydrazide. One of the mutants, R. sphaeroides MJ7, was defective in glutamate uptake but showed wild-type levels of binding protein. The mutant showed no chemotactic response to glutamate. Both glutamate uptake and chemotaxis were recovered when the gltP gene, coding for the H(+)-linked glutamate carrier of E. coli, was expressed in R. sphaeroides MJ7. It is concluded that the chemotactic response to glutamate strictly requires uptake of glutamate, supporting the view that intracellular metabolism is needed for chemotaxis in R. sphaeroides.

Characterization of a binding protein-dependent glutamate transport system of Rhodobacter sphaeroides

The mechanism of L-glutamate uptake was studied in Rhodobacter sphaeroides. Uptake of L-glutamate is mediated by a high-affinity (Kt of 1.2 microM), shock-sensitive transport system that is inhibited by vanadate and dependent on the internal pH. From the shock fluid, an L-glutamate-binding protein was isolated and purified. The protein binds L-glutamate (apparent Kd of 1.3 microM) and L-glutamine (Ki of 15 microM) with high affinity. The expression level of this binding protein is maximal at limiting concentrations of glutamine in the growth medium. The glutamate-binding protein restores the uptake of L-glutamate in spheroplasts. L-Aspartate is a strong competitive inhibitor of L-glutamate uptake (Ki of 3 microM) but competes only poorly with L-glutamate for binding to the binding protein (Ki of > 200 microM). The uptake of L-aspartate in R. sphaeroides also involves a binding protein which is distinct from the L-glutamate-binding protein. These data suggest that in R. sphaeroides, the L-glutamate- and L-aspartate-binding proteins interact with the same membrane transporter.

Characterization of the epoxide hydrolase from an epichlorohydrin-degrading Pseudomonas sp

An epoxide hydrolase was purified to homogeneity from the epichlorohydrin-utilizing bacterium Pseudomonas sp. strain AD1. The enzyme was found to be a monomeric protein with a molecular mass of 35 kDa. With epichlorohydrin as the substrate, the enzyme followed Michaelis-Menten kinetics with a Km value of 0.3 mM and a Vmax of 34 mumol.min-1.mg protein-1. The epoxide hydrolase catalyzed the hydrolysis of several epoxides, including epichlorohydrin, epibromohydrin, epoxyoctane and styrene epoxide. With all chiral compounds tested, both stereoisomers were converted. Amino acid sequencing of cyanogen bromide-generated peptides did not yield sequences with similarities to other known proteins.

Assessment of the late proliferative phase endometrium by ultrasonography in patients undergoing in-vitro fertilization and embryo transfer (IVF/ET)

This study reports on 330 women aged 29 to 45 years, who underwent 411 cycles of in-vitro fertilization and embryo transfer (IVF/ET). Vaginal sonograms were performed during the late proliferative phase of natural cycles and cycles of controlled ovarian hyperstimulation (COH) with gonadotrophins, to evaluate both the thickness and echogenicity of the endometrium. Findings classified as Grade I; characterized by homogeneous echogenicity of the endometrium, and Grade II; characterized by an outer peripheral layer of dense echogenicity surrounding a central sonolucent area (i.e. a 'halo pattern'). Grades I and II were subclassified on the basis of thickness into A (greater than or equal to 9 mm) and B (less than 9 mm). Grade IIA ('optimal') was associated with a clinical pregnancy rate per embryo transfer of 33% while Grades IA, IB and IIB ('poor') were associated with a rate of only 7%. Women aged 41-45 years experienced a 25% incidence of 'poor' sonographic grades while the incidence in women less than or equal to 40 years of age was 5%. The presence of various uterine pathologies was associated with 'poor' endometrial grades in 86% of cases while only 11% of normal uteri manifested 'poor' grades. 'Optimal' endometrial grades in natural cycles were consistently associated with 'optimal' grades in ensuing cycles of COH (96%). Women with 'poor' endometrial grades in natural cycles improved in 55% of cases during subsequent COH. The results of this study indicate that sonographic assessment of the endometrial lining in the late proliferative phase during both natural and COH cycles is a valuable method for screening and managing IVF/ET candidates.

Ovulation prediction by monitoring salivary and vaginal electrical resistance with the PEAK Ovulation Predictor

We investigated the ability of the PEAK Ovulation Predictor to predict the expected date of ovulation in 21 infertile, spontaneously ovulating women. A nonsignificant correlation (R = 0.15; P = .51) existed between the predicted date of ovulation and the day of the serum LH peak. A moderately strong correlation (R = 0.61; P less than .01) was observed between the day of the salivary electrical resistance peak and that of the serum LH peak. However, the serum LH peak occurred between 4-9 days after an identified peak in salivary electrical resistance. Twice-daily urine LH testing correlated strongly with both the serum LH peak (R = 0.93; P = .0001) and the ultrasound-detected day of ovulation (R = 0.81; P = .0001). A statistically significant peak in the mean salivary or vaginal electrical resistance on a particular day relative to the day of the serum LH peak could not be demonstrated. When identified, the nadir in vaginal electrical resistance occurred no earlier than 2 days before the serum LH peak and thus may mark the endpoint of the fertile period for natural family planning methods. We conclude that, whereas the PEAK Ovulation Predictor is of little value in accurately predicting ovulation, measurements of salivary and vaginal electrical resistance may be helpful in timing inseminations. However, for detection of the serum LH surge, twice-daily urine LH testing demonstrated a stronger correlation and narrower frequency distribution than did those determinations based on electrical resistance.

Parametric modeling of somatosensory evoked potentials

In this paper, we examine methods of characterizing somatosensory evoked potentials (SEP's) in both the time and frequency domains. We have found that the truncated impulse response (TIR) method produced an accurate time domain model of the SEP signals at model orders greatly reduced from the original state space matrix. The TIR method was valuable for smoothing signals that were slightly corrupted by noise. In this case, the simulated data sequence was close to the original data sequence in the mean squared error sense. For signals that were greatly corrupted by noise, the TIR method was not able to perform as well. Therefore, the TIR method was not a feature extraction method but was valuable for data simulation. In the frequency domain, we have used the autoregressive moving average model (ARMA) to parameterize the SEP signal. An overdetermined set of Yule-Walker equations was created to determine the autoregressive (AR) parameters of the original data with the model order established by the singular value decomposition. From these AR parameters, a residual time series was generated which was used to find the moving average parameters. The resulting ARMA model was used to produce a simulated data sequence. The frequency domain characteristics of the simulated sequence and the corresponding power spectral density of the ARMA filter were very close to the periodogram of the original data sequence. Accurate parameterization was achieved for the SEP waveforms at low filter lengths.

Endometrial cytosolic and nuclear progesterone receptors in the luteal phase defect

Basal body temperature profiles, serial serum progesterone levels, and serial endometrial biopsies were studied in 15 infertile women during 21 ovulatory cycles. Ten cycles (in 9 women) demonstrated luteal phase defects (LPD), diagnosed by a histological lag in endometrial maturation, normal luteal phase length, and normal luteal phase serum progesterone levels. Both normal and LPD cycles had a maximum amount of endometrial cytosolic progesterone receptor (PgR) on days 13-15, with a significant decline thereafter. LPD cycles had significantly lower endometrial nuclear PgR concentrations than did normal cycles during the proliferative phase, but luteal phase endometrial nuclear PgR levels were similar in both groups. In 2 LPD women treated with dydrogesterone, normal endometrial maturation and a decline in endometrial cytosolic PgR concentrations in the late luteal phase were found. Therefore, with the exception of endometrial nuclear PgR concentrations during the proliferative phase, we found no evidence for a major abnormality in endometrial PgR levels in LPD cycles with a lag in endometrial histology.

Uterine media proteins in the rat during gestation

Uterine proteins secreted in response to estrogen and modulated by progesterone have previously been demonstrated in the immature rat. An in vitro radiolabeling technique with 35S-methionine was used to culture uteri from animals in estrus, pregnancy and the post partum period. Proteins released into the media (media proteins) were analyzed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. On Days 1 and 2 of pregnancy, a 115,000 M.W.--protein similar in molecular weight to one previously described by this laboratory--is prominent. Its disappearance by Day 3 coincides with increased progesterone secretion. The appearance of a 43,000 M.W. protein is the most marked change at the time of blastocyst invasion of the uterine epithelium. A new 160,000 M.W. protein begins to emerge on Day 5 and is prominent in later gestation. The latter protein is thought to be a product of the uterine decidua. Its production in ovariectomized animals is increased in the presence of progesterone and a nonspecific decidual stimulus. In the immediate post partum period, a 115,000 M.W. protein reemerges, and the 160,000 M.W. protein disappears. It is believed that these proteins are influenced by the hormonal events of pregnancy and may represent an expression of the genetic control of gestation.

Sex and the boards

In 1978 a questionnaire on the functioning of the American Board of Psychiatry and Neurology was mailed to a sample of APA members. The authors present the significant differences in responses between men and women psychiatrists. A higher percentage of women than men were among thoes who had experienced stress from the time and effort involved in taking the Board examinations and from fear of the oral examination; 45% of the women respondents who had received certification had done so since 1975 versus 23% for the men. The authors discuss possible explanations for the sex differences, including role strain, and suggest greater flexibility in where , when, and how Board examinations can be taken.

Clinical experience with theophylline. Relarionships between dosage, serum concentration, and toxicity

Relationships between theophylline dosage, serum theophylline concentration, and theophylline toxicity were evaluated retrospectively in 47 hospitalized adults. The amount of theophylline administered daily varied more than sixfold, from 6 to 38 mg/kg. The serum theophylline concentrations, however, varied 24-fold from 2 to 49 mug/ml. The relationship between daily dosage and serum concentration was unpredictable in an individual patient. Fourteen patients (30%) had a toxic reaction to theophylline. Toxic symptoms, which were not always gastrointestinal, occurred commonly with serum concentrations over 25 mug/ml but were not noted with concentrations below 15 mug/ml. High serum theophylline concentrations and a toxic reaction developed just as often with the oral route as when the drug was given intravenously. In six patients, measurement of serum theophylline concentration disclosed subtherapeutic concentrations. Serum theophylline determination appears to be important clinically in guiding effective and safe usage of theophylline.

Unilateral lung function. Comparison of the lateral position test with radionuclide ventilation-perfusion studies

Twenty-seven patients underwent studies of unilateral lung function by the lateral-position test (LPT) and by computer-analyzed radionuclide imaging of ventilation and perfusion. The patients were divided into two groups, symmetric or asymmetric, on the basis of the physical examination of the chest and the chest radiograph. In patients with symmetry, the estimate of unilateral lung function by the LPT and isotopic estimates for unilateral lung volume, unilateral distribution of tidal volume, and unilateral perfusion, agreed within 2 percent, 4 percent, and 3 percent, respectively. In patients with asymmetry, the differences were 9 percent, 8 percent, and 13 percent. In settings of marked unilateral ventilation-perfusion imbalance, the LPT primarily reflected ventilation. Prediction of unilateral ventilatory function based upon the LPT and spirometric measurements agreed closely with unilateral ventilation determined isotopically by 133xenon, even in the presence of chronic obstructive lung disease. Our results confirm that the LPT provides valid information about unilateral lung function.

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