Venoocclusive disease of the liver: development of a model for predicting fatal outcome after marrow transplantation

PURPOSE

Hepatic venoocclusive disease (VOD) is a common complication of cytoreductive therapy for marrow transplantation. Only 25% of patients who develop VOD have severe disease. We tested the hypothesis that early clinical signs of VOD would predict which patients would recover and which would die.

PATIENTS AND METHODS

We evaluated 355 consecutive patients who had transplants between August 6, 1987 and July 21, 1988 for occurrence of VOD and whether it was reversible within 100 days of transplant. Total serum bilirubin and weight gain from day -7 through day +16 posttransplant were compared among patients with no, severe, or nonsevere VOD. Logistic regression models were developed to estimate probabilities of severe VOD at each of six time intervals. The accuracy of these models was tested by applying them to 392 consecutive patients who underwent transplantation between July 22, 1988 and July 20, 1989.

RESULTS

As early as day -1, bilirubin and weight gain were significantly different between patients whose VOD proved to be severe and patients with reversible VOD or no disease. Regression models were used to generate coefficients (beta 0, beta 1, beta 2) for the equation P = 1/(1 + e-z), where P is the probability of severe VOD and z = beta 0 + beta 1 (In total serum bilirubin [mg/dL]) + beta 2 (percent weight gain). Application of this equation to the next 392 patients allowed us to calculate sensitivity, specificity, and positive predictive value for a range of probabilities.

CONCLUSION

The course of VOD after cytoreductive therapy can be predicted by knowing the serum bilirubin and weight gained within 1 to 2 weeks of transplantation. Probability estimates derived from patient data are highly specific and moderately sensitive. Such probability estimates may be useful when considering potentially risky interventions to treat VOD, such as recombinant human tissue plasminogen activator.

Statistical design and monitoring of the Carotene and Retinol Efficacy Trial (CARET)

CARET is a chemoprevention trial of beta-carotene and vitamin A with lung cancer as the primary outcome. Participants at high risk for lung cancer are drawn from two populations: asbestos-exposed workers and heavy smokers. The intervention is a daily combination of 30 mg beta-carotene and 25,000 IU vitamin A as retinyl palmitate. Nearly 18,000 participants will be followed for a mean 6 years, yielding over 100,000 person-years of follow-up. We project that this sample size will have 80% power to detect a 23% decrease in the incidence of lung cancer cases. The purpose of this paper is to present the values of the key sample size parameters of CARET; our schemes for monitoring CARET for sample size adequacy, incidence of side effects, and efficacy of the study vitamins; an overview of the data collected; and plans for the primary, secondary, and ancillary analyses to be performed at the end of the trial. These approaches to the design, monitoring, and analysis of CARET are applicable for many other prevention trials.

Effect of DMSO exposure without cryopreservation on hematopoietic progenitor cells

Colligative cryoprotectants must be non-toxic at the high concentrations required for protection of cells from freeze-injury. Human hematopoietic stem cells are usually cryopreserved in a solution containing 1.6 molal (10% v/v) DMSO. We studied the chemical toxicity of this agent to myeloid and erythroid progenitor cells from healthy donors. No DMSO toxicity was found at concentrations of 5% or 10% at either 4 degrees or 37 degrees C for incubation durations up to 1 h. DMSO at 20% did not decrease the number of progenitor cell-derived colonies per 5 x 10(4) cells cultured, but did result in cell clumping during DMSO washout, resulting in a net loss of progenitor cells. At a concentration of 40% DMSO, a direct toxicity to hematopoietic progenitors was found. Delay in removal of DMSO after thawing of cryopreserved cells for periods up to 1 h was also non-toxic to hematopoietic progenitor cells. Direct addition of DMSO at 1% or 10% final concentration (v/v) to the culture dishes suppressed colony formation. These data suggest that DMSO is not toxic to haematopoietic progenitor cells after short-term exposure at the concentrations used for cryopreservation of marrow and peripheral blood stem cells.

Effects on response rates and costs of stamps vs business reply in a mail survey of physicians

In the general population, the use of stamps rather than business reply postage significantly improves response rates in mail surveys. Among physicians, however, a smaller effect might be anticipated due to their greater sophistication. An experiment was conducted to test the hypothesis that stamps would improve response rates and lower costs in a physician survey that included intensive follow up. In 1989, 380 physicians who reported providing primary care were surveyed. The protocol included two mailings, a postcard reminder, and two telephone reminders. Physicians were randomly assigned to receive a return envelope with a first-class stamp or an envelope that had been preprinted "business reply mail" in the first and second mailings. Response rates, calculated as completed surveys divided by eligible physicians, were 83.8 and 72.1% for stamps and business reply respectively, a difference of 11.7 percentage points (p < 0.01). Moreover, the total cost per completed survey was $11.18 for the physicians receiving stamps and $14.25 for the physicians receiving business reply. As in mail surveys of the general public, the use of first-class stamps on return envelopes both improves response rates and reduces cost in surveys of physicians.

Splanchnic resuscitation: a strategy for preventing liver failure in sepsis

Liver failure is commonly encountered in the critically ill, septic patient. This hepatic dysfunction occurs as a wide spectrum of abnormalities, ranging from mild chemical derangements to fulminant liver failure. The syndrome of multiple system organ system failure due to sepsis is often complicated by alterations in splanchnic/hepatic function. Knowledge of gut pathophysiology with resultant changes in substrate metabolism, synthetic function, cytokine release, and the detrimental effects on other organ systems is rapidly expanding. The functions of these pathophysiologically produced factors include extensive autocrine, paracrine, and endocrine effects. Evidence suggests that adequate resuscitation during sepsis, which is measured by systemic end-points, may result in inadequate splanchnic blood flow and oxygen delivery. The addition of serial measurements of splanchnic end-points may limit the hepatic failure encountered in multiple system organ failure due to sepsis.

Chloride alters renal blood flow autoregulation in deoxycorticosterone-treated rats

Renal blood flow autoregulation was studied in deoxycorticosterone acetate (DOCA)-treated rats. DOCA pellets (75 mg) were implanted in uninephrectomized rats, and the animals were then fed one of four diets: (1) normal sodium chloride level, (2) high in NaCl, (3) high in chloride, or (4) high in sodium. After 40 to 45 days of the DOCA-diet treatment, animals were subjected to renal blood flow autoregulation experiments; an inflatable aortic occluder was placed proximal to the renal artery, and renal blood flow (electromagnetic flow probe) was measured while renal perfusion pressure was reduced from normal (in that animal) to 20 mm Hg, in 10 mm Hg decrements to determine the lower threshold of autoregulation. Directly measured arterial blood pressure was higher in the DOCA-high NaCl group compared with the DOCA-normal NaCl group (127 +/- 3 mm Hg vs 103 +/- 4 mm Hg) during anesthesia. Significant elevation of lower autoregulatory thresholds were demonstrated in both the DOCA-high NaCl (98 +/- 7 mm Hg) and high chloride groups (94 +/- 3 mm Hg) compared with the DOCA-normal NaCl (77 +/- 4 mm Hg) and the DOCA-high sodium (76 +/- 5 mm Hg). Pressure-flow curves of the DOCA-high chloride groups were shifted significantly downward (reduced renal blood flow at all pressures) and rightward (elevated lower threshold) compared with the DOCA-normal NaCl and -high sodium groups. These data indicate that DOCA-treated rats consuming a diet high in chloride have altered renal blood flow autoregulatory mechanisms.

The effects of heparin and dietary fish oil on embolic events and the microcirculation downstream from a small-artery repair

In recent studies we demonstrated that platelet emboli induced by arterial injury impair the microcirculation. The present study was performed to determine if heparin or dietary cod liver oil reduces the incidence of emboli following the same arterial injury and, in turn, whether these agents prevent the associated decrease in microcirculatory blood flow. The cremaster muscle of 29 male Sprague-Dawley rats was isolated on a single neurovascular bundle consisting of the iliac artery and vein and the genitofemoral nerve. Emboli were generated by a thrombogenic injury of the iliac artery, and their number and their subsequent effect on capillary perfusion in the downstream microcirculation were measured. Nine animals received heparin (10-unit IV bolus plus 10 units/hour IV infusion), 10 were fed cod liver oil (10 percent by weight of food) for 3 weeks prior to the experiment, and 9 animals receiving no treatment served as controls. The number of emboli was significantly reduced in the heparin group, but there was no accompanying improvement in capillary perfusion. In contrast, in the cod liver oil group, the number of emboli was not reduced, but there was significant improvement in capillary perfusion. These findings suggest that the harmful effect that platelet emboli have on the microcirculation is probably biochemical in nature (vasoconstriction) rather than related to simple mechanical obstruction to flow.

Experimental study of the relationship between alterations in tissue perfusion and anastomotic patency

It is generally believed that alterations in perfusion which endanger a free flap or replant are directly related to thrombus formation and obstruction of blood flow at the anastomotic site. Recent experimental work in our laboratory suggests that the presence of platelet emboli downstream in the microcirculation might be responsible at least in part for postoperative perturbations in perfusion. To determine whether changes in tissue perfusion can occur in the absence of corresponding changes in anastomotic patency we studied microvascular blood flow in the exposed rat cremaster flap model. We made continuous measurements of both anastomotic patency and downstream microcirculatory perfusion following small vessel repair. Using this approach we found that during one hour after clamp release and reperfusion in the 10 animals studied, pedicle artery blood pressure, which indicates pedicle patency in this model, was functionally normal 97% +/- 2 of the time while blood flow in the downstream tissue (cremaster) remained normal an average of only 65% +/- 7 of the time. In most cases these flow alterations were associated with the presence of visible platelet emboli in the microcirculation. From these studies we conclude that when flap perfusion failure temporarily occurs, a microsurgeon must consider not only the anastomosis but also the downstream microcirculation when searching for a possible cause.

Skeletal muscle arteriolar constriction to ANG II: evaluation of a myogenic component

This study addressed the hypothesis that an increase in blood pressure contributes to the overall constrictive response of skeletal muscle arterioles to angiotensin II (ANG II). Diameters of second-order arterioles (2A) and third-order arterioles (3A) in the rat cremaster muscle were quantitated after intravenous administration of ANG II. Hindquarter blood pressure was either allowed to increase or was maintained at normal levels. Constriction of 3A to bolus injection of ANG II was the same whether hindquarter pressure increased or not. However, the total vascular constrictive response of the cremaster muscle (based on 2A blood flow) and of the entire hindquarter (based on iliac arterial blood flow) to bolus ANG II was greater when hindquarter pressure was held constant. During slow infusion of ANG II, 3A constriction was unaffected by an abrupt decrease or increase in hindquarter pressure. However, an abrupt reduction of hindquarter pressure caused a significant decline in hindquarter vascular resistance. Thus an increase in blood pressure, whether rapid or gradual, does not influence 3A constriction to ANG II. However, in the entire hindquarter, a rapid rise in blood pressure opposes constriction to ANG II, whereas a gradual pressure rise evokes a mechanism that enhances constrictive response to the peptide.

The purification and characterization of arsenite oxidase from Alcaligenes faecalis, a molybdenum-containing hydroxylase

The purification and initial characterization of arsenite oxidase from Alcaligenes faecalis are described. The enzyme consists of a monomer of 85 kDa containing one molybdenum, five or six irons, and inorganic sulfide. In the presence of denaturants arsenite oxidase releases a fluorescent material with spectral properties identical to the pterin cofactor released by the hydroxylase class of molybdenum-containing enzymes. Azurin and a c-type cytochrome, both isolated from A. faecalis, each serves as an electron acceptor to arsenite oxidase and may form a periplasmic electron transfer pathway for arsenite detoxification. Full reduction of arsenite oxidase requires 3-4 reducing equivalents, using either arsenite or dithionite as the electron source. Below 20 K, oxidized arsenite oxidase exhibits an EPR signal with g values of 2.03, 2.01, and 2.00, which integrates to approximately 0.4 spins/protein. Since enrichment in 57Fe results in broadening of this EPR signal, the center giving rise to this signal must contain iron. The most plausible candidates are a [4Fe-4S] high potential iron protein center or a [3Fe-4S] center. The EPR signal observed in oxidized arsenite oxidase disappears upon reduction of the protein with either arsenite or dithionite. Concomitantly, a rhombic EPR signal (g = 2.03, 1.89, 1.76) appears which is similar to that of Rieske-type [2Fe-2S] clusters and spin quantifies to one spin/protein.

Microcirculatory disturbances following the passage of emboli in an experimental free-flap model

Following completion of arterial repair in an experimental free-flap model, platelet emboli have been observed passing through the microcirculation downstream. The purpose of this experimental study was to observe and quantitate changes in capillary perfusion occurring subsequent to these events. The isolated rat cremaster model was used. For 6 hours subsequent to surgical injury of the main artery in this model, the number of emboli and the number of perfused capillaries downstream were counted. In eight rats having an intentional arterial wall injury, emboli were consistently seen during the first hour of reflow. In the nine control animals having no arterial injury, no emboli were seen. The presence of emboli in the cremaster muscle, resulting from the arterial injury, was associated with a significant reduction in the number of perfused capillaries. We suggest that the observed decrease in capillary perfusion was associated with microemboli that produced an adverse effect for several hours after their initial presence in the circulation.

Assessment and treatment strategies for depressive disorders commonly encountered in primary care settings

Frequently overlooked, depression is a very common complex disorder that causes significant morbidity and mortality. This article provides a review of three commonly encountered depressive disorders in primary care settings: adjustment disorder with depressed mood, dysthymia and major depression. Since many individuals minimize the affective symptoms of depression, clinicians must maintain a high index of suspicion when clients present with vague somatic complaints, such as fatigue, headache, constipation and difficulty sleeping. To reach an accurate diagnosis, a thorough history, physical examination and appropriate laboratory studies should be performed. Numerous rating scales are presented to aid assessment. Common intervention strategies for the treatment of depressive disorders include education, drug therapy, and supportive individual and family counseling.

Correlates of maintenance of a low-fat diet among women in the Women's Health Trial

BACKGROUND

The Women's Health Trial (WHT) was a feasibility study for a randomized controlled trial designed to test the hypothesis that a reduction in dietary fat reduces breast cancer incidence among women age 45 to 69. Between 1984 and 1988, 2,064 women participated in its two phases.

METHODS

A follow-up study of 525 women who were randomized to receive the WHT dietary intervention program was conducted to assess maintenance of the diet 1 year on average after the trial ended. Among 448 participants, the mean percentage of energy from fat as measured by a food frequency questionnaire was 40.0% at baseline, 26.3% at the end of the trial, and 27.7% at follow-up. Based on 408 women with complete data, a recursive model was estimated, describing the influence of baseline characteristics of the women on attendance at intervention program sessions, adherence to the diet during the trial, and long-term maintenance of the diet after the trial ended. The effects of women's experiences during the trial on adherence and long-term maintenance were investigated as well.

RESULTS

Attendance at the educational sessions was strongly related to adherence to the diet during the trial (P less than 0.001), and adherence was the most important predictor of long-term maintenance (P less than 0.001). The percentage of energy from dietary fat at baseline was an important correlate of both adherence (P less than 0.001) and long-term maintenance (P less than 0.001). College-educated women were more likely to adhere to the diet during the trial (P less than 0.001). Feelings of deprivation adversely affected long-term maintenance (P less than 0.01), primarily through their effect on adherence during the trial (P = 0.01). Costliness of the diet in time and money negatively influenced long-term maintenance (P less than 0.05). Development of a distaste for fat encouraged adherence (P = 0.06).

CONCLUSIONS

The low-fat dietary pattern established during the WHT was maintained for as long as 20 months after the trial ended. A recursive model was useful in analyzing the process and correlates of long-term maintenance of dietary behavior change. Both predisposing variables and women's experiences while on a low-fat diet were associated with long-term maintenance. The results suggest that feelings of deprivation should be avoided, perhaps by use of low-fat substitutes, by those attempting to lower their dietary fat and that more research is needed on the development of a distaste for fat among individuals who adopt low-fat diets.

Serotype prevalence of Candida albicans from blood culture isolates

Blood culture isolates of Candida albicans were collected from 102 patients in Seattle, Wash., hospitals (n = 77) and Hong Kong (n = 25). The patients were classified by immune status into two groups. Group I patients were severely immunosppression, and group II patients had underlying risk factors for candidemia but no underlying immunosuppression. Serotyping by Hasenclever tube agglutination was done. In the Seattle area, the odds of fungemia with type B C. albicans were 3.62 times greater than the odds of type B fungemia in group II patients. Although the odds ratio could not be computed for Hong Kong patients, the direction of the relationship in this population was consistent with the data on Seattle patients. Despite the magnitude of the odds ratios, the relative prevalence of type B over type A in group I compared with group II was not significant when analyzed separately by region, probably because of relatively low numbers of isolates in group II. Accepting that the effect of immune status on serotype is equivalent across regions but presupposing that a regional effect on type B prevalence exists, the pooled odds for fungemia with serotype B in group I patients are increased 5.4-fold over those of group II patients. Logistic regression analysis controlling for region gave similar results.

Reduced neutrophil superoxide generation and plasma lipoperoxide levels in pigs fed with cod liver oil

Circulating neutrophils, isolated from pigs fed for 8 weeks with a diet supplemented with CLO, had an accentuated n-3 fatty acid incorporation into the plasma membrane, as evidenced by an approximately four-fold greater n-3/n-6 ratio as compared with the control diet group. Moreover, the neutrophils of the CLO fed pigs produced less superoxide when stimulated with PMA or f-MLP, as well as showing a more prolonged latency period before O2(-)-generation. In the plasma of pigs fed with CLO there were higher levels of thiobarbituric reactive material and lipofuscin, while the content of GSSG was similar in both dietary groups. The results of this study indicate that dietary supplementation with CLO reduces the activation of circulating neutrophils and favours the presence in the plasma of lipoperoxides.

Small artery resistance increases during the development of renal hypertension

Vascular pressures were measured in the principal (A1) arteriole and in upstream small arteries of the rat cremaster muscle to investigate vascular resistance changes associated with one-kidney, one clip Goldblatt hypertension. Pressure measurements were made at a proximal and distal site of each vessel using a servonull micropipette system. Vessel diameters were measured using video microscopy. A1 arteriole and external spermatic artery diameters were both decreased after 2 and 4 weeks of hypertension. Mean arterial pressure was elevated after 2 weeks of hypertension (106 +/- 4 mm Hg versus 140 +/- 5 mm Hg). Likewise, vascular pressures were elevated at every site: pudicepigastric artery (36%), external spermatic artery (47%), and A1 arteriole (38%). The pressure drop along the external spermatic artery was increased (87%) after 2 weeks of hypertension. Mean arterial pressure was further elevated from 2-4 weeks of hypertension (105 +/- 4 mm Hg versus 162 +/- 7 mm Hg) but only the proximal pudic-epigastric artery pressure was further elevated during this time from 2 to 4 weeks (131 +/- 5 mm Hg versus 147 +/- 7 mm Hg) of hypertension development. This was associated with an increased pressure drop (87%) along the artery compared with the situation at 2 weeks. These data indicate that small arteries upstream from the microcirculation contribute significantly to the increase in vascular resistance during hypertension. In addition, these data indicate that the increases in small artery resistance do not develop uniformly throughout all vessel branches.

Poor surgical technique produces more emboli after arterial anastomosis of an island flap

To answer the question "Are more emboli produced after a small artery anastomosis has been performed poorly?", we used the isolated rat cremaster muscle. The number of emboli seen downstream from a small artery anastomosis were counted after using two anastomotic techniques. Direct observations using intravital microscopy of emboli passing through the principal arteriole of the cremaster revealed that surgical technique using a large needle (poor execution) caused a significantly higher number of emboli to be produced at the site of small artery anastomosis than was noted after a fine needle technique.

Lack of correlation between mast cell response and active anaphylaxis in mice

Mast cell-competent mice, sensitized to lysozyme, were examined for their mast cell and anaphylactic responses to determine whether anaphylactic shock could occur independent of mast cell participation. Tissues (cremaster muscle, subdermal connective tissue and mesentery), taken a short time after intravenous antigenic challenge, showed no evidence of mast cell degranulation above control tissues. Data obtained from a quantitative comparison of the onset and increase in local and systemic anaphylactic and mast cell sensitivities to the antigen provide strong support for the view that mast cells are not the major effector cells for systemic anaphylaxis in mice. The significant increase in blood pressure that occurred immediately after infusion with the antigen also indicates that other cells within the blood stream are involved.

MMPI special scale clinical correlates for adolescent inpatients

Little research has focused on the clinical correlates of adolescents' Minnesota Multiphasic Personality Inventory (MMPI) special scale responses. We investigated the clinical correlates of the MacAndrew Alcoholism Scale (MAC), Anxiety (A), Repression (R), and Ego Strength (Es) scales, based on self-reported data from 68 inpatient adolescents and ratings by their nursing staff and individual therapists. Parametric and nonparametric analyses revealed patterns of clinically relevant descriptors for these scales in a manner largely consistent with findings derived from studies of adult respondents. Results are discussed in terms of implications for interpretation of each of these special scales and in relation to a general approach to understanding adolescents' MMPI profiles.

The effect of photodynamic therapy on tumor oxygenation

Oxygen microelectrodes were used to measure tumor partial pressure of oxygen (PO2) before and after photodynamic therapy (PDT) in a rat transplantable subcutaneous chondrosarcoma. Before PDT there was a gradient of PO2 from the superficial layers of the tumor (PO2 = 46 +/- 6 mm Hg) toward the center of the tumor (PO2 = 10 +/- 1 mm Hg). Mean tumor PO2 (21 +/- 2 mm Hg) was significantly reduced to 3 +/- 1 mm Hg 1 hour after PDT, and this reduction in PO2 persisted 4 hours (8 +/- 2 mm Hg) and 24 hours (6 +/- 1 mm Hg) after PDT. The largest percentage decrease in PO2 occurred at a depth of only 50 microns into the tumor. Inasmuch as PDT has been shown to decrease blood flow, our data suggest that PDT actions on blood vessels in the peripheral areas of the tumor are of major importance for eliciting the tumor hypoxia that contributes to tumor necrosis after PDT.

Vascular isolation of the rat cremaster muscle

The vascular supply to the rat cremaster muscle was completely isolated to provide a microvascular preparation with a controllable blood flow. The anatomy of the cremaster vascular supply and the surgical approach to isolate the cremaster muscle on its neurovascular pedicle are described. The functional integrity of this isolated cremaster preparation was tested using intravital video microscopy to evaluate the tissue's response to vasoactive agents and to peripheral nerve stimulation. The isolated cremaster muscle was positioned in situ in a controlled tissue bath and concentration response curves to the topical application of norepinephrine (NE) and acetylcholine (Ach) were determined. Vasoconstriction elicited by the topical application of NE or by stimulation of the genitofemoral nerve trunk was similar for both the isolated and standard cremaster preparations. Application of 10(-5) M Ach caused maximal vasodilation equal to that produced by 10(-3) M papaverine in both preparations. In summary, the isolated cremaster muscle of the rat is an acceptable model of a skeletal muscle microcirculation which can be used to investigate microvascular function when precise monitoring or control of perfusion to the entire muscle is needed.

Postrenal modification of urine in birds

The role of the cloaca and lower intestine in the postrenal modification of urine was studied in conscious normally hydrated desert quail. The birds were studied for a period of 12 days during which they were in intake-output balance. It was calculated that of the combined mixture of urine-feces entering the lower intestine, 47% water, 62% sodium, and 49% potassium were reabsorbed. If this material is considered as coming from the ureteral urine, then the composition of the ureteral urine entering the lower intestine was changed as follows: 77% water, 72% sodium, and 82% potassium were reabsorbed. For urate, 68% of the total present in ureteral urine was degraded in the lower intestine. In terms of the filtered load produced by the kidneys, the lower intestine reabsorbed 1.5% filtered water, 0.4% filtered sodium, and 46% filtered potassium. The total filtered loads reabsorbed by the combined efforts of the kidney and lower intestine were 99.5% water, 99.8% sodium, and 88% potassium. It appears that the cloaca and lower intestine of birds may serve a similar function to that of the distal nephron in mammals, making the fine adjustments in water and sodium reabsorption from the urine.

Inhibition of histamine-induced protein leakage in rat skeletal muscle by blockade of prostaglandin synthesis

The effects of two prostaglandin synthesis blockers, indomethacin and mefenemic acid, on both histamine-induced extravasation of albumin and arteriole dilation were studied using intravital fluorescent microscopy. Sprague-Dawley rats (140-180 g) were anesthetized with pentobarbital (50mg/Kg) and the cremaster muscle was positioned in a Krebs bath (pH = 7.4, PCO2 = 40 mm Hg, PO2 = 35 mm Hg, temp = 34 degrees). Fluorescein isothiocyanate-labeled albumin was injected intravascularly and the fluorescent image of the cremaster microcirculation was produced by illumination from an argon laser (488 nm). Videotape analysis of the experiments showed that increasing concentrations of histamine in the bath produced both a concentration-dependent arteriole dilation and a concentration-dependent leakage of labeled albumin into the interstitium. Adding indomethacin (10 or 100 micrograms/ml) or mefenemic acid (10 micrograms/ml) to the Krebs bath significantly diminished the protein leakage induced by histamine but did not alter the arteriole dilation. These results indicate that prostaglandins may be directly involved in the histamine-induced increase in vascular permeability to macromolecules but not in the arteriole dilation histamine produces.

Reactions with the oxidized iron protein of Azotobacter vinelandii nitrogenase: formation of a 2Fe center

The Fe-S center of oxidized Fe protein from Azotobacter vinelandii nitrogenase is decomposed by alpha,alpha'-dipyridyl in a biphasic process. In the presence of MgATP, 2 Fe are immediately removed by chelation while the additional irons are removed only after several hours. A slower biphasic Fe release also was observed in the presence of chelator alone. MgADP prevented the Fe release by chelator. An intermediate in the reaction was isolated containing 2 Fe. The visible spectrum of the intermediate was similar to that of 2Fe-2S ferredoxins (epsilon max at 325, 416, and 460 nm of 16.1, 11.3, and 9.0 mM-1 cm-1). The 2Fe form was electron paramagnetic resonance (EPR) silent until partially reduced with sodium dithionite. The EPR spectral properties were similar to 2Fe-2S ferredoxins; namely, the Fe center had resonances at g = 2.00, 1.94, and 1.92 which were detectable, essentially unbroadened at 70 K. The results suggest that in the oxidized (2+) state Fe protein can undergo a 4Fe to 2Fe conversion.

Protein loss induced by complement activation during peritoneal dialysis

A variable loss of macromolecules during peritoneal dialysis has been noted in both humans and experimental animals. We investigated the potential role of the complement system for inducing protein loss during peritoneal dialysis, both to shed light on clinical variability of protein loss and to develop a model for quantitatively studying complement-induced microvascular protein leakage. Rats received intra-arterial injections of a fluorescent dye conjugated to rat serum albumin and underwent a 3.5-hr series of 15-min peritoneal dialysis exchanges. After the control exchanges, rats received either intra-arterial zymosan-activated rat serum, saline, unactivated rat serum, or endotoxin; other rats received an intraperitoneal injection of endotoxin, histamine, phenylephrine, or nitroprusside. The drainage volume from each exchange was measured, and the concentrations of labeled albumin, total protein, and urea were determined by spectroscopy. Zymosan-activated rat serum and endotoxin injections (both intraperitoneal and intra-arterial), each of which may activate the alternative pathway of complement, produced a dramatic increase in dialysate protein concentrations. In addition, histamine, which is a vasodilator but which may also be involved as a mediator of the activated complement system and/or endotoxemia, also produced an increase in dialysate protein concentrations. On the other hand, drugs which may alter peritoneal blood flow such as the vasodilator nitroprusside or the vasoconstrictor phenylephrine, did not affect dialysate protein concentrations. These data suggest that activation of the alternative pathway of complement may cause variation in protein loss during peritoneal dialysis and that in some situations, pharmacological control of this system could be an important therapeutic consideration.

Cecae of desert quail: importance in modifying the urine

The importance of the digestive ceca in the modification of ureteral urine was evaluated in conscious, unrestrained desert quail. Cecaectomized (Cx) birds took in slightly more food and water and excreted more solids and water than did sham operated controls. The percent utilization of food for the Cx birds was 76 and 79% for the sham operated controls. Urate output was 47 ml/kg day for Cx and 41 ml/kg day for the sham operated controls. Water content of the excrement was 90% for the Cx and 85% for the sham operated controls. There was a slight but insignificant increase in uric acid excretion in the droppings of cecaectomized birds.

A comparison of trends in mortality from stroke in the United States and Rochester, Minnesota

More uniform methods of diagnosis and determination of the cause of death result in greater reliability of trends in mortality from stroke. In all categories of stroke except subarachnoid hemorrhage, the mortality rates in Rochester, Minnesota, are lower and show a more rapid decline with time than in the United States as a whole. The differential between the rates for United States white population and the Rochester population is most evident in the older age groups. This difference may be due to the effects of revisions in the International Classification of Disease and/or to the assignment of nonstroke deaths to stroke causes in the United States as a whole to a greater extent than in Rochester. Whether different patterns of medical care affect the trends in stroke mortality has not been determined. The trends in mortality from various categories of stroke in Rochester are reliable because some of the inconsistencies of diagnosis, assignment of cause of death, and coding changes have been overcome. The decline in mortality rates for Rochester corresponds well with decreasing incidence rates and lack of change in case fatality rates previously reported.

Total luminescence spectroscopy of fluorescence changes during aging in Caenorhabditis elegans

Total luminescence spectroscopy was employed to characterize and quantitate age-related changes in fluorescence in the nematode Caenorhabditis elegans, an established model for aging research. The excitation wavelength was varied between 250 and 590 nm in 10-nm increments. At each excitation wavelength, the emission wavelength was varied between 300 and 600 nm. Contour plots of corrected spectra were made. All fluorescence increased severalfold with age, except for that ascribed to tryptophan of soluble protein fractions. This general increase included fluorescence due to flavins, which is not expected to increase with age but has previously been observed to do so in this species. Blue emission peaks that approximated Schiff base product fluorescence were detected in whole aqueous homogenates, chloroform/methanol extracts, and detergent-cleaned cuticle preparations. Age-related increases in emission intensities of these peaks were demonstrated in aqueous homogenates and isolated cuticles. Cuticle preparations, known to be rich in collagenous protein, exhibited a fluorescence peak that approximated the recently described pyridinoline cross-link of vertebrate collagen. This peak, as well as the entire cuticle emission spectrum between 300 and 500 nm, increased dramatically with age. A fluorescence peak tentatively identified as cuticle tyrosine, characteristic of collagenous protein, also increased in older worms. The effectiveness of the spectroscopic technique in distinguishing individual fluorescence peaks in complex mixtures was demonstrated, and the potential of the nematode cuticle for age-related collagen studies was identified.

Synthesis and evaluation of some stable multisubstrate adducts as inhibitors of catechol O-methyltransferase

A new series of methylase inhibitors has been designed in which the nucleophilic methyl acceptor is attached to the adenosine and/or homocysteine fragments of the methyl donor, S-adenosylmethionine, to form a "multisubstrate adduct". In the present case, catecholamine analogues attached through a phenethyl sulfide linkage to 5'-thioadenosine or homocysteine have been synthesized, together with the corresponding methylsulfonium salts. These compounds were assayed as inhibitors of catechol O-methyltransferase, and the adenosylsulfonium salts (4) were found to be inhibitors of the enzyme.

Pyrrol[1,4]benzodiazepine antibiotics. Proposed structures and characteristics of the in vitro deoxyribonucleic acid adducts of anthramycin, tomaymycin, sibiromycin, and neothramycins A and B

The pyrrol[1,4]benzodiazepine antibiotics anthramycin, tomaymycin, sibiromycin, and neothramycins A and B are potent antitumor agents that bind to DNA in a unique manner, resulting in some unusual biological consequences. This paper describes results on which the points of covalent linkage between the drugs (carbinolamine carbon atom) and DNA (N-2 of guanine) are deduced, as well as Corey-Pauling-Koltun (CPK) models for the various drug-DNA adducts. Predictions based upon these CPK models have been tested, and the results are reported in this paper. These tested experimental predictions include (1) instability of the drug-DNA adducts to denaturation of DNA, (2) saturation binding limits, (3) effect of drug binding on the structure of DNA, (4) lack of unwinding and in vitro strand breakage of closed-circular supercoiled simian virus 40 (SV-40) DNA, (5) sensitivity of the secondary structure of DNA to drug binding, (6) hydrodynamic properties of the drug-DNA adducts, (7) hydrogen bonding of the 9-phenolic proton in anthramycin to DNA, (8) structure-activity relationships, and (9) biological consequences of DNA damage, including cumulative damage and slow excision repair, double-strain breaks in DNA in repair-proficient cells, and the selective inhibition of H-strand DNA synthesis in mitochondria. The results are completely in accord with our postulated space-filling models.

Induction of myeloperoxidase deficiency in granulocytes in lead-intoxicated dogs

Lead interferes with heme synthesis in erythrocytes and has a deleterious effect on red cell membranes. We measured myeloperoxidase (MPO) enzyme activity in the granulocytes of dogs fed increasing quantities of lead. Concurrently, iodination capability and in vitro bactericidal activity were measured. Blood lead levels were monitored. Three of 4 dogs poisoned with lead developed significant decreases in MPO enzyme activity in their granulocytes. The decline in MPO activity correlated with cumulative lead toxicity as judged by blood lead levels and clinical signs of lead poisoning. Iodination ability in all 4 dogs decreased with cumulative lead toxicity. After discontinuation of lead administration, recovery of granulocyte MPO activity preceded recovery of iodination ability. This observation suggests the possibility of separate effects of lead on iodination ability and MPO activity. Moderate impairment of bactericidal capacity developed in 3 of 4 dogs with severe lead poisoning. Clinical infections were not observed during the course of the study.