Locomotor effects of a fibrosis-based immune response in stickleback fish

The vertebrate immune system provides an impressively effective defense against parasites and pathogens. However, these benefits must be balanced against a range of costly side-effects including energy loss and risks of auto-immunity. These costs might include biomechanical impairment of movement, but little is known about the intersection between immunity and biomechanics. Here, we show that a fibrosis immune response to Schistocephalus solidus infection in freshwater threespine stickleback (Gasterosteus aculeatus) has collateral effects on their locomotion. Although fibrosis is effective at reducing infection, some populations of stickleback actively suppress this immune response, possibly because the costs of fibrosis outweigh the benefits. We quantified the locomotor effects of the fibrosis immune response in the absence of parasites to investigate whether there are incidental costs of fibrosis that could help explain why some fish forego this effective defense. To do this, we induced fibrosis in stickleback and then tested their C-start escape performance. Additionally, we measured the severity of fibrosis, body stiffness and body curvature during the escape response. We were able to estimate performance costs of fibrosis by including these variables as intermediates in a structural equation model. This model revealed that among control fish without fibrosis, there is a performance cost associated with increased body stiffness. However, fish with fibrosis did not experience this cost but rather displayed increased performance with higher fibrosis severity. This result demonstrates that the adaptive landscape of immune responses can be complex with the potential for wide-reaching and unexpected fitness consequences.

Locomotor effects of a fibrosis-based immune response in stickleback fish

The vertebrate immune system provides an impressively effective defense against parasites and pathogens. However, these benefits must be balanced against a range of costly side-effects including energy loss and risks of auto-immunity. These costs might include biomechanical impairment of movement, but little is known about the intersection between immunity and biomechanics. Here, we show that a fibrosis immune response in threespine stickleback (Gasterosteus aculeatus) has collateral effects on their locomotion. When freshwater stickleback are infected with the tapeworm parasite Schistocephalus solidus, they face an array of fitness consequences ranging from impaired body condition and fertility to an increased risk of mortality. To fight the infection, some stickleback will initiate a fibrosis immune response in which they produce excess collagenous tissue in their coelom. Although fibrosis is effective at reducing infection, some populations of stickleback actively suppress this immune response, possibly because the costs of fibrosis outweigh the benefits. Here we quantify the locomotor effects of the fibrosis immune response in the absence of parasites to investigate whether there are collateral costs of fibrosis that could help explain why some fish forego this effective defense. To do this, we induce fibrosis in stickleback and then test their C-start escape performance. Additionally, we measure the severity of fibrosis, body stiffness, and body curvature during the escape response. We were able to estimate performance costs of fibrosis by including these variables as intermediates in a structural equation model. This model reveals that among control fish without fibrosis, there is a performance cost associated with increased body stiffness. However, fish with fibrosis did not experience this cost but rather displayed increased performance with higher fibrosis severity. This result demonstrates that the adaptive landscape of immune responses can be complex with the potential for wide reaching and unexpected fitness consequences.

Dermal Denticle Diversity in Sharks: Novel Patterns on the Interbranchial Skin

Shark skin is covered in dermal denticles—tooth-like structures consisting of enameloid, dentine, and a central pulp cavity. Previous studies have demonstrated differences in denticle morphology both among species and across different body regions within a species, including one report of extreme morphological variation within a 1 cm distance on the skin covering the branchial pouches, a region termed “interbranchial skin.” We used gel-based profilometry, histology, and scanning electron microscopy to quantify differences in denticle morphology and surface topography of interbranchial skin denticles among 13 species of sharks to better understand the surface structure of this region. We show that (1) interbranchial skin denticles differ across shark species, and (2) denticles on the leading edge of the skin covering each gill pouch have different morphology and surface topography compared with denticles on the trailing edge. Across all species studied, there were significant differences in denticle length (P = 0.01) and width (P = 0.002), with shorter and wider leading edge denticles compared with trailing edge denticles. Surface skew was also higher in leading edge denticles (P = 0.009), though most values were still negative, indicating a surface texture more dominated by valleys than peaks. Overall, leading edge denticles were smoother-edged than trailing edge denticles in all of the species studied. These data suggest two hypotheses: (1) smoother-edged leading edge denticles protect the previous gill flap from abrasion during respiration, and (2) ridged denticle morphology at the trailing edge might alter water turbulence exiting branchial pouches after passing over the gills. Future studies will focus on determining the relationship between denticle morphology and water flow by visualizing fluid motion over interbranchial denticles during in vivo respiration.

Cardiovascular collapse during ethanol sclerotherapy in a pediatric patient

Ethanol sclerotherapy is a first line management therapy for low flow vascular malformations. It is usually performed under general anesthesia because of the pain associated with ethanol injection. Ethanol sclerotherapy frequently produces minor local complications but may rarely produce catastrophic cardiopulmonary complications. This report describes the cardiovascular collapse associated with an ethanol sclerotherapy procedure in an 11-year- old child. The evidence for ethanol-induced cardiovascular derangements is discussed.

Parastomal pyoderma gangrenosum: clinical features and management

BACKGROUND

The importance of pyoderma gangrenosum (PG) as a cause of ulceration around abdominal stomas is not well recognized.

OBJECTIVE

Our purpose was to describe the incidence, clinical and histologic features, disease associations, and possible risk factors for parastomal PG.

METHODS

A clinic, run by a dermatologist and two stoma nurses, was created. Five hundred patients approached by postal questionnaire were invited to attend if they had skin problems. In addition, local surgical, dermatologic, and nursing services were invited to refer patients with parastomal skin problems. Cases of parastomal PG were identified, investigated, and treated.

RESULTS

The annual incidence of parastomal PG in the questionnaire-based cohort of patients was 0.6% (3 patients). An additional 23 patients with the condition were seen. No consistent hematologic, biochemical, immunologic, microbiological or histologic abnormalities were identified. Local skin damage did not appear to be an important trigger for parastomal PG. The condition is recurrent in one third of cases. Topical tacrolimus (0.3% in carmellose sodium paste) has been effective in 4 patients.

CONCLUSION

Parastomal PG is far more common than previous reports would suggest, and it may be associated with diseases other than inflammatory bowel disease.

Sweet's syndrome and polycythaemia rubra vera

Sweet's syndrome is associated with haematological malignancy, particularly acute myelogenous leukaemia, but there are few reports of its association with polycythaemia rubra vera. We describe an 85-year-old man with polycythaemia rubra vera who developed Sweet's syndrome and review the literature of this association.

Pulmonary infiltrates, eosinophilia, and cardiomyopathy following corticosteroid withdrawal in patients with asthma receiving zafirlukast

CONTEXT

Zafirlukast is a potent leukotriene antagonist that recently was approved for the treatment of asthma. As use of this drug increases, adverse events that occur at low frequency or in populations not studied in premarketing clinical trials may become evident.

OBJECTIVE

To describe a clinical syndrome associated with zafirlukast therapy.

DESIGN

Case series.

PATIENTS

Eight adults (7 women and 1 man) with steroid-dependent asthma who received zafirlukast.

MAIN OUTCOME MEASURES

Development of a clinical syndrome characterized by pulmonary infiltrates, cardiomyopathy, and eosinophilia following the withdrawal of corticosteroid treatment.

RESULTS

The clinical syndrome developed while patients were receiving zafirlukast from 3 days to 4 months and from 3 days to 3 months after corticosteroid withdrawal. All 8 patients developed leukocytosis (range, 14.5-27.6 x 10(9)/L) with eosinophilia (range, 0.19-0.71). Six patients had fever (temperature >38.5 degrees C), 7 had muscle pain, 6 had sinusitis, and 6 had biopsy evidence of eosinophilic tissue infiltration. The clinical syndrome improved with discontinuation of zafirlukast treatment and reinitiation of corticosteroid treatment or addition of cyclophosphamide treatment.

COMMENT

Development of pulmonary infiltrates, cardiomyopathy, and eosinophilia may have occurred independent of zafirlukast use or may have resulted from an allergic response to this medication. We suspect that these patients may have had a primary eosinophilic infiltrative disorder that had been clinically recognized as asthma, was quelled by steroid treatment, and was unmasked following corticosteroid withdrawal facilitated by zafirlukast.

Effect of the stress of medical residency training on the overnight dexamethasone suppression test

Forty-two medical residents and interns were studied to evaluate the effect of the stress of medical residency training on-call nights on the hypothalamic-pituitary-adrenal axis. Dexamethasone 1 mg was given at 11:00 p.m. on two separate occasions; a control (off-call) night and on on-call night. Plasma cortisol was measured between 8:00-9:00 a.m. the following morning. The number of patient admissions during the on-call night and the number of hours of sleep during both on-call and control nights were recorded. Plasma cortisol decreased to < 138 nmol/l (< 5 micrograms/dl) in 41 out of 42 (97.6%) of the participants following an on-call day and in 40 out of 42 (95.2%) participants after the control day. The number of hours of sleep during the on-call night was 3.9 +/- 0.29 and during the control night 7.0 +/- 0.11 hours and the number of patient admissions was 3.1 +/- 0.3. In conclusion General Internal Medicine on-call experience does not produce significant alteration on the hypothalamic-pituitary-adrenal axis.

Effects of recombinant human IGF-I on glucose and leucine kinetics in men

To examine the effects of recombinant human (rh) insulin-like growth factor I (IGF-I), insulin, and saline on metabolic parameters, we studied 20 young nonobese healthy men. Euglycemic clamps with 240-min IGF-I infusions at two doses (49 and 33 pmol.kg-1 x min-1, n = 8 and 12 subjects) were performed and compared with hyperinsulinemic-euglycemic clamps (2.25 pmol.kg-1 x min-1, n = 9). Leucine and glucose kinetics were examined with L-[1-13C]leucine and [3-3H]glucose. Glucose rate of appearance (Ra) declined equivalently in the 49 pmol.kg-1.min-1 IGF-I and insulin clamps but remained at basal levels during the 33 pmol.kg-1 x min-1 IGF-I infusions. In contrast, Rd of glucose was increased by 176% in the 49 pmol.kg-1 x min-1 IGF-I and 78% in the 33 pmol.kg-1 x min-1 IGF-I infusions. Furthermore, to prevent hypoglycemia after the termination of both rhIGF-I infusions, it was necessary to infuse glucose for an additional 2-20 h. Ra of leucine was suppressed significantly by both IGF-I and insulin, whereas leucine oxidation was not affected by either hormone. Therefore, the rate of disappearance of leucine expressed as the difference between Ra and oxidation rates was significantly reduced in all clamps. In addition, IGF-I significantly suppressed beta-cell secretion without affecting the other glucoregulatory hormones. In contrast to insulin, IGF-I had no apparent effect on lipolysis, as measured by changes in nonesterified fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential evaluation of islet cell responses to glucose in the transplanted pancreas in humans

We evaluated the hormonal and metabolic responses of denervated pancreas allografts in nine volunteers 3 to 12 months after the transplant (initial) and again 1 year later (follow-up). Eight of the patients received simultaneous pancreas-kidney transplants. The glucose clamp technique was used to create a square wave of hyperglycemia 5.5 mmol/L above the basal glucose level for 2 hours. A biphasic insulin response was evident in each subject, both initially and at follow-up. The initial plasma insulin response was fourfold higher in patients with pancreas-kidney transplants than in normal volunteers. However, the plasma insulin response of the patients with pancreas-kidney transplants at the follow-up study was more similar to that of the normal controls. The plasma glucagon levels were elevated in follow-up clamp studies. Hepatic glucose production and glucose disposal were similar in both studies. At the follow-up examination only, GLUT4, the major insulin-sensitive glucose transporter, was measured in muscle homogenates by immunoblotting. GLUT4 levels in the patients with pancreas-kidney transplants were only 55% as abundant as in normal volunteers. This may be due, in part, to immunosuppressive therapy or to persistent, albeit reduced, levels of hyperinsulinemia even 2 years after transplantation. We concluded that, despite systemic drainage of the pancreas and immunosuppressive therapy, pancreatic insulin secretion, peripheral insulin levels, and muscle insulin responsiveness are restored toward normal levels approximately 2 years after the transplant.

Clinical comparison of Gentle-Haler Actuator and Aerochamber Spacer for Metered Dose Inhaler (MDI) use by asthmatics

Spacing devices such as the Aerochamber have been shown to improve delivery of medication from MDIs in patients who could not use proper technique with an MDI alone, but the Aerochamber may be inconvenient to carry & use because of its bulkiness. We therefore compared clinical responses of asthmatics using a new, smaller MDI actuator (Gentle-Haler) with no spacer to their responses using a standard MDI actuator & spacer (Aerochamber).

METHODS

We treated 30 asthmatic patients in 2 sessions with the beta-agonist albuterol using the above-mentioned devices. Both devices were utilized in each treatment session, with one delivering albuterol & the other generating a placebo. During the second session on a different day, the albuterol & placebo were reversed with respect to the two devices. On each study day, physiologic measurements of FEV1, FVC, FEF25-75, blood pressure, & pulse were obtained at pretreatment (baseline) & after treatment at 15 & 30 minutes & 1, 2, 3, 4, 5 & 6 hours. Analysis of variance & Student's t test were used to compare the ratio of physiologic responses to albuterol delivered with the two devices.

RESULTS

Both devices were equally effective in eliciting desirable increases in FEV1, FEF25-75, & FVC. No statistically significant differences (5% significance level) in effectiveness of the albuterol were associated with the use of either device. A very small (< 7%) but statistically significant reduction in diastolic blood pressure (3 of 8 time points) & systolic pressure (1 of 8 time points) was associated with the use of the Gentle-Haler.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial energy production and consumption remain balanced during positive inotropic stimulation when coronary flow is restricted to basal rates in rabbit heart

The effect on myocardial energy balance of increasing oxygen demand without altering basal myocardial perfusion rate was assessed in isolated, isovolumic, retrograde blood perfused rabbit hearts. Myocardial energy requirements were increased with paired stimulation. The capacity of rapid paired stimulation to increase mechanical energy consumption was demonstrated in the presence of increased perfusion with the rate X pressure product and oxygen consumption increasing 86 and 148%, respectively, compared with control values. In contrast, rapid paired stimulation under constant, basal flow conditions did not alter the rate X pressure product, while oxygen extraction and consumption increased only 40% relative to control. Myocardial ATP, creatine-phosphate, and lactate content were identical under control and constant flow-paired stimulation conditions. The results of this study indicate that no detectable energy imbalance was produced by rapid paired stimulation with flow held constant at basal rates. These results suggest that the myocardium does not increase mechanical energy expenditure in response to inotropic or rate stimulation in the presence of restricted flow reserve and are inconsistent with the concept of "demand-induced" or "relative" myocardial ischemia.

Acetoacetyl-CoA ligase activity in the isolated rat hepatocyte: effects of 25-hydroxycholesterol and high density lipoprotein

The activity of acetoacetyl-CoA (AcAc-CoA) ligase (E.C.6.2.1.16) in hepatocytes from rats was shown to be the same as the activity in homogenates of their livers. In hepatocytes treated with 25-hydroxycholesterol, AcAc-CoA ligase, 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase and rates of sterol synthesis were substantially decreased. Hepatocytes treated with high density lipoprotein (HDL) exhibited a 2 to 4 fold induction of HMG-CoA reductase activity; however an accompanying increase in AcAc-CoA ligase activity and the rate of cholesterol synthesis was not observed. We conclude (a) that increases in the activity of HMG-CoA reductase when mediated by HDL in hepatocytes do not result in a corresponding change in the capacity for sterol synthesis and (b) that changes in the activity state of HMG-CoA reductase can be dissociated from that of AcAc-CoA ligase.

The regulation of acetoacetyl-CoA synthetase activity by modulators of cholesterol synthesis in vivo and the utilization of acetoacetate for cholesterogenesis

[3-14C]Acetoacetate, injected subcutaneously into rats, was rapidly incorporated into hepatic cholesterol and fatty acids. Injection of radiolabeled acetoacetate, acetate, or glucose resulted in the preferential incorporation of acetoacetate into cholesterol. The postmitochondrial supernatant of a rat liver homogenate has the capacity to synthesize radiolabeled sterols from [3-14C]acetoacetate, and this capacity surpasses its capacity to utilize [1-14C]acetate. The activity of acetoacetyl-CoA synthetase, a cytoplasmic enzyme that activates acetoacetate, was found to be highly regulated by modulators known to affect the activity of 3-hydroxy-3-methylglutaryl-CoA reductase and/or cholesterol biosynthesis in liver and adrenals of adult rats. Acetoacetyl-CoA synthetase activity was depressed by feeding cholesterol or mevalonate administration and was enhanced by the addition to the diet of mevinolin and/or cholestyramine. The activity of acetoacetyl-CoA synthetase in adrenals was enhanced by treatment of the animals with 4-aminopyrazolopyrimidine. These changes in activity of acetoacetyl-CoA synthetase were in synchrony with changes in the activities of 3-hydroxy-3-methylglutaryl-CoA synthase and 3-hydroxy-3-methylglutaryl-CoA reductase. The evidence suggests that the regulation of acetoacetyl-CoA synthetase activity and the utilization of acetoacetate for lipogenesis is closely linked to the regulation of cholesterogenesis.

Bacteriology of the lower respiratory tract as determined by fiber-optic bronchoscopy and transtracheal aspiration

For assessment of the validity of cultures of tracheobronchial secretions and exudates (TBSE) obtained by fiber-optic bronchoscopy, the aerobic and anaerobic flora of expectorated saliva and TBSE obtained by fiber-optic bronchoscopy from nine healthy volunteers and eight patients were compared with those obtained by fiber-optic bronchoscopy as well). Normal volunteers yielded both aerobic and anaerobic bacteria in amounts usually less than 104.5 colony-forming units (cfu)/ml in TBSE obtained by fiberoptic bronchoscopy. In patients with chronic bronchitis, 42 isolates of aerobic bacteria (104-105.5 cfu/ml) and only 10 isolates of anaerobes (usually less than 104 cfu/ml) were reovered from 15 samples obtained by trantracheal aspiration. The data lead to the conclusion that low-level contamination (less than or equal to 104 cfu/ml) with oral flora is common in TBSE obtained by fiber-optic bronchoscopy. A single potential pathogen in numbers of greater than or equal to 105 cfu/ml may be of etiologic significance, particularly if recovered from purulent drainage material from a localized portion of the lung. Under circumstances in which quantitative bacteriology cannot be done, TBSE obtained by transtracheal aspiration will most reliably reflect the bacterial flora present in the lung.

Penetration of antimicrobial agents into bronchial secretions

The entry of ampicillin, cephalothin and gentamicin into traceobronchopulmonary secretions/exudates was assessed in 22 patients during 28, episodes of pneumonia or bronchitis. Specimens were collected from the lower respiratory tract via tracheostomies or endotracheal tubes using either the flexible fiberoptic bronchoscope (50 specimens) or an intratracheal catheter (59 specimens). Venous blood was obtained at the same time. The concentrations in the bronchial specimens were less than those in the corresponding serums, amounting to about 10 per cent with ampicillin, 25 per cent with cephalothin and equal to or greater than 40 per cent with gentamicin.

Trimethoprim-sulfamethoxazole in chronic bronchitis

Authenic tracheobronchial secretions/exudates (TBSE) were aspirated under direct vision via a sterile catheter passed through a fiberoptic bronchoscope from patients with chronic obstructive pulmonary disease complicated by chronic bronchitis. TBSE, saliva and blood were obtained during long-term administration of trimethoprim-sulfamethoxazole (TMP-SMX) and were assayed for drug content. Before and during treatment TBSE were cultured qualitatively and quantitatively for aerobic and anaerobic bacteria, fungi, mycoplasmas and viruses. Treatment with TMP-SMX was associated with a decrease in the recovery of Hemophilus influenzae, H. parainfluenzae, Klebsiella pneumoniae, Escherichia coli and Proteus mirabilis; however, little effect was observed on the typically nonpathogenic aerobic and anaerobic bacteria of the upper respiratory tract. TMP was found in saliva at concentrations greater than in serum. Both TMP and SMX entered TBSE in absolute and relative concentrations sufficient to take advantage of the potential for synergy against susceptible microorganisms. Patient tolerance of TMP-SMX was generally good and several patients reported a decrease in production of sputum during treatment.