A Prospective Observational Study of Hepatic Dysfunction in Children on Antitubercular Drugs

The frequency, risk factors, and prognosis of antitubercular drug-induced liver injury (TB-DILI) was assessed in this prospective observational study. All consecutive children < 18 y put on antitubercular therapy (ATT) for pulmonary or extrapulmonary tuberculosis between July 2019 and December 2020 were included. Liver function tests (LFTs) were done at baseline and at 2, 4, 6 wk, and then 2 monthly after initiation of therapy till completion of ATT regimen. A total of 81 children [14.27 ± 3.38 y, 34 (42%) males] were included. Out of the patients enrolled, 10 (12.3%) developed TB-DILI at a median of 8.5 (3-18) d of starting ATT. All patients were symptomatic with the most common symptoms being anorexia and nausea (80%). A higher baseline ALT was independently associated with DILI with adjusted OR 2.1 (95% CI 1.3-3.4), p = 0.01. Eight patients tolerated reintroduction of ATT in a sequential manner, 9-24 d after discontinuation.

Psychiatric morbidity among patients attending a rural non-communicable disease clinic

Background

The presence of psychiatric illness among patients with physical illnesses leads to poor treatment adherence, poor lifestyle, increased cost of treatment, poor quality of life, worsening of physical illness, work absenteeism, increased hospital visits, poor self-care and higher mortality. The study evaluated the prevalence of cognitive impairment and psychiatric morbidity in non-communicable disease patients. The study highlights that NCD patients should be provided information about the development of cognitive impairment in order to prevent it.

Methods

It was a cross-sectional study conducted among the patients attending the non-communicable disease clinic of a rural community health centre run in collaboration with the Postgraduate Institute Medical Education and Research (PGIMER), Chandigarh. We registered 124 patients after obtaining written informed consent. Instruments: Hindi Mental Status Examination (HMSE), Patient Health Questionnaire-9, Generalized anxiety disorder-7 (GAD-7) scale. Analysis of covariance was applied to see the relationship between the domain of the HMSE and NCDs.

Results

The mean age of the participants was 55.5 years (SD-11.9, Range-26-90). A little more than one third (N = 48, 38.7%) were diagnosed with hypertension only, one-sixth (N = 22; 17.7%) were diagnosed with diabetes mellitus only, and 54 (43.5%) patients were diagnosed with both hypertension and diabetes mellitus. A slightly more than one-third of the study participants were diagnosed with depressive disorder (N = 44, 35.5%), and 29% (N = 36) of the participants were diagnosed with an anxiety disorder. About one-fourth of patients with NCD have cognitive impairment and 39.51% have psychiatric morbidity.

Conclusions

The prevalence of cognitive impairment is higher among patients of NCD with psychiatric morbidity. Patients with NCDs should be routinely screened for cognitive functioning and provided information about the development of cognitive impairment.

Key messages

Because of high prevalence of cognitive impairment and psychiatric morbidity in NCD patients, patients should be provided information to prevent it. There is a need to screen NCD patients routinely for cognitive functioning, and provide them information to prevent cognitive impairment.

Characterization of ICAM-1 biophore to design cytoadherence blocking peptides

Peptides from natural sources are good starting material to design bioactive agents with desired therapeutic property. IB peptide derived from the ICAM-1 has been studied extensively as an agent to disrupt the non-specific binding of lymphocyte to the endothelial cells. ICAM-1: IB molecular model reveals that IB peptide binds in an extended conformation to the ICAM-1, masking LFA-1 and partially covering PfEMP-1 binding site. Considering the regioselective requirement of ICAM-1: PfEMP1 binding site, IB peptide charge and 3-D conformation are optimized through generation of combinatorial peptide library containing single, double, triple, tetra and quadra amino acid substitutions of IB peptide. Further, truncation of IB peptide followed by molecular modeling studies gave us the biophoric environment of the IB peptide required for its activity. Molecular modeling of these peptides into the binding site indicates that these complexes are fitting well into the site and making extensive interactions with the residues crucial for PfEMP-1 binding. Molecular dynamics simulations were performed for 10ns each under four different temperatures to estimate comparative stability of ICAM1: IB peptide complexes. The designed peptide ICAM1: IBT213 has comparable stability at ambient temperature, while ICAM1: IBT1 shows a greater degree of robustness at higher temperatures. Overall, the study has given useful insights into IB peptide binding site on ICAM1 and its potential in designing novel peptides to disrupt the cytoadherence complex involving ICAM1: PfEMP1.

Cryopreservation of quince (Cydonia oblonga Mill.)

BACKGROUND

Quince (Cydonia oblonga Mill.) has great potential for utilisation in pharmaceutical and food industries.

OBJECTIVE

The study was to develop an efficient cryopreservation approach for quince.

METHODS

Factors on the survival and regrowth such as cold acclimation, explant type and recovery media composition were assessed. The effectiveness of the resultant protocols for a number of quince cultivars was determined.

RESULTS AND CONCLUSION

Quince shoot tips and nodal sections are successfully cryopreserved. Sustained regrowth of quince Angers A was observed after encapsulation-osmoprotection/dehydration, encapsulation-dehydration and PVS2 vitrification. The highest regrowth rate (80%) was obtained from explants excised from cold hardened shoots and cryopreserved using encapsulation-osmoprotection/dehydration and vitrification protocols. The optimised vitrification protocol in combination with shoot cold hardening and a MS recovery medium without activated charcoal and auxin resulted in satisfactory regrowth of shoots from six quince cultivars. The morphology of acclimatised plants derived from cryopreserved shoots was comparable with non-cryopreserved plants.

Bioavailability of iodine in the UK-Peak District environment and its human bioaccessibility: an assessment of the causes of historical goitre in this area

Iodine is an essential micronutrient for human health. Its deficiency causes a number of functional and developmental abnormalities such as goitre. The limestone region of Derbyshire, UK was goitre-endemic until it declined from the 1930s and the reason for this has escaped a conclusive explanation. The present study investigates the cause(s) of goitre in the UK-Peak District area through an assessment of iodine in terms of its environmental mobility, bioavailability, uptake into the food chain and human bioaccessibility. The goitre-endemic limestone area is compared with the background millstone grit area of the UK-Peak District. The findings of this study show that 'total' environmental iodine is not linked to goitre in the limestone area, but the governing factors include iodine mobility, bioavailability and bioaccessibility. Compared with the millstone grit area, higher soil pH and calcium content of the limestone area restrict iodine mobility in this area, also soil organic carbon in the limestone area is influential in binding the iodine to the soil. Higher calcium content in the limestone area is an important factor in terms of strongly fixing the iodine to the soil. Higher iodine bioaccessibility in the millstone grit than the limestone area suggests that its oral bioaccessibility is restricted in the limestone area. Iodine taken up by plant roots is transported freely into the aerial plant parts in the millstone grit area unlike the limestone area, thus providing higher iodine into the human food chain in the millstone grit area through grazing animals unlike the goitre-prevalent limestone area.

Lead contamination of surgical gloves by contact with a lead hand

Background. “Lead hands” are frequently used to maintain hand and finger position in hand surgery. The malleability and strength of lead make it ideal for this purpose. The aim of this study was to determine the amount of lead transferred to a surgeon's glove during handling of a lead hand. Method. Sterile surgical gloves were wiped over the surface of a lead hand. The number of wipes was varied, the gloves were then sent to a trace elements laboratory, and the lead content transferred to each glove was determined. Results. The amount of lead transferred to each glove increased with increasing exposure to the lead hand. After twenty wipes, up to 2 mg of lead was transferred to the surgeon's glove. Covering the lead hand with a sterile drape markedly reduced the lead transferred to the surgeon's glove. Conclusion. Significant amount of lead is transferred on to the gloves after handling a lead hand. This risks wound contamination and a foreign body reaction. Covering the lead hand with a sterile drape may minimise the risk of surgical wound contamination.

Oswestry Disability Index scoring made easy

INTRODUCTION

Low back pain effects up to 80% of the population at some time during their active life. Questionnaires are available to help measure pain and disability. The Oswestry Disability Index (ODI) is the most commonly used outcome measure for low back pain. The aim of this study was to see if training in completing the ODI forms improved the scoring accuracy.

PATIENTS AND METHODS

The last 100 ODI forms completed in a hospital's spinal clinic were reviewed retrospectively and errors in the scoring were identified. Staff members involved in scoring the questionnaire were made aware of the errors and the correct method of scoring explained. A chart was created with all possible scores to aid the staff with scoring. A prospective audit on 50 questionnaires was subsequently performed.

RESULTS

The retrospective study showed that 33 of the 100 forms had been incorrectly scored. All questionnaires where one or more sections were not completed by the patient were incorrectly scored. A scoring chart was developed and staff training was implemented. This reduced the error rate to 14% in the prospective audit.

CONCLUSIONS

Clinicians applying outcome measures should read the appropriate literature to ensure they understand the scoring system. Staff must then be given adequate training in the application of the questionnaires.

Circadian output, input, and intracellular oscillators: insights into the circadian systems of single cells

Circadian output comprises the business end of circadian systems in terms of adaptive significance. Work on Neurospora pioneered the molecular analysis of circadian output mechanisms, and insights from this model system continue to illuminate the pathways through which clocks control metabolism and overt rhythms. In Neurospora, virtually every strain examined in the context of rhythms bears the band allele that helps to clarify the overt rhythm in asexual development. Recent cloning of band showed it to be an allele of ras-1 and to affect a wide variety of signaling pathways yielding enhanced light responses and asexual development. These can be largely phenocopied by treatments that increase levels of intracellular reactive oxygen species. Although output is often unidirectional, analysis of the prd-4 gene provided an alternative paradigm in which output feeds back to affect input. prd-4 is an allele of checkpoint kinase-2 that bypasses the requirement for DNA damage to activate this kinase; FRQ is normally a substrate of activated Chk2, so in Chk2(PRD-4), FRQ is precociously phosphorylated and the clock cycles more quickly. Finally, recent adaptation of luciferase to fully function in Neurospora now allows the core FRQ/WCC feedback loop to be followed in real time under conditions where it no longer controls the overt rhythm in development. This ability can be used to describe the hierarchical relationships among FRQ-Less Oscillators (FLOs) and to see which are connected to the circadian system. The nitrate reductase oscillator appears to be connected, but the oscillator controlling the long-period rhythm elicited upon choline starvation appears completely disconnected from the circadian system; it can be seen to run with a very long noncompensated 60-120-hour period length under conditions where the circadian FRQ/WCC oscillator continues to cycle with a fully compensated circadian 22-hour period.

A circadian clock in Neurospora: how genes and proteins cooperate to produce a sustained, entrainable, and compensated biological oscillator with a period of about a day

Neurospora has proven to be a tractable model system for understanding the molecular bases of circadian rhythms in eukaryotes. At the core of the circadian oscillatory system is a negative feedback loop in which two transcription factors, WC-1 and WC-2, act together to drive expression of the frq gene. WC-2 enters the promoter region of frq coincident with increases in frq expression and then exits when the cycle of transcription is over, whereas WC-1 can always be found there. FRQ promotes the phosphorylation of the WCs, thereby decreasing their activity, and phosphorylation of FRQ then leads to its turnover, allowing the cycle to reinitiate. By understanding the action of light and temperature on frq and FRQ expression, the molecular basis of circadian entrainment to environmental light and temperature cues can be understood, and recently a specific role for casein kinase 2 has been found in the mechanism underlying circadian temperature-compensation. These data promise molecular explanations for all of the canonical circadian properties of this model system, providing biochemical answers and regulatory logic that may be extended to more complex eukaryotes including humans.

Trochanteric non-union--does it influence the rate of revision following primary total hip replacement? A minimum of 15 years follow-up

OBJECTIVE

Trochanteric non-union may alter the biomechanics and the forces going through the hip joint leading to increased polyethylene wear and hence a higher revision rate. The aim of our study was to determine if trochanteric non-union was associated with a higher incidence of acetabular and/ or femoral revision for mechanical failure, i.e. aseptic loosening.

MATERIALS AND METHODS

Three hundred and twenty-six total hip replacements performed in 318 patients between 1979 and 1989 were reviewed. The status of the trochanter was determined using the senior author's (JPH) classification of trochanteric union/non-union. The mean follow-up was 16.7 years (15-25 years).

RESULTS

20.5% (61/297) of hips with united trochanter and 20.6% (6/29) with un-united trochanter had been revised at the latest follow-up. The difference was not significant (p-value > 0.1, odds ratio 1.01).

CONCLUSION

We could not find any influence of trochanteric non-union on acetabular or femoral revision rate over a mean follow-up period of 17 years (range 15-25 years).

Bacteriology swab in primary total hip arthroplasty-- does it have a role?

Infection in joint replacement is a devastating complication, and in spite of the advances in surgery, it remains a challenge. The rate of deep infection following primary hip/knee arthroplasty is between 1% and 2%. The aim of this study was to determine whether obtaining bacteriology swabs at the time of surgery could help in further reducing the rate of infection following joint arthroplasty. A bacteriology swab of the synovial fluid was taken after opening the capsule of the hip joint and was sent for culture and sensitivity. Out of 142 swabs sent, four (2.1%) were found to be positive. Three of these patients were treated with antibiotics after obtaining sensitivities. None of the patients developed deep infection. Bacteriology swab in primary joint arthroplasty may have a role and may help in further reducing the incidence of deep infection in joint replacement surgery.

C reactive protein and skin temperature post total knee replacement

We prospectively assessed 20 patients following uncomplicated total knee replacement (TKR). Clinical status, skin temperature and C-reactive protein (CRP) were measured preoperatively and at intervals up to 18 weeks. The CRP rose postoperatively up to 5-7 days but returned to normal values by 6 weeks. The skin temperature remained elevated up to 18 weeks. We concluded that in uncomplicated cases, the CRP should be within normal limits by 6 weeks after operation, but skin temperature may remain elevated up to 18 weeks. A sustained rise in these values may indicate the development of a complication such as infection and the patient must be closely monitored.

Anti-adhesion molecule strategies as potential neuroprotective agents in cerebral ischemia: a critical review of the literature

Despite recent advances in the understanding of the pathophysiology of cerebral ischemia, current approaches attempting to prevent ischemic brain damage after an acute stroke remain quite inadequate. Today, ischemic stroke remains the third leading cause of death in industrialized nations, and the leading cause of disability requiring long term institutional care in the U.S and other industrialized nations. While one treatment, tissue plasminogen activator, has shown efficacy in clinical trials, safety concerns limit its role in clinical practice to a narrow time window of use. Acute cerebral ischemia has been shown to evoke a profound and deleterious upregulation of the inflammatory response, initiated within the cerebral microvasculature. Recently, research efforts have focused on targeting individual components of the inflammatory cascade, such as leukocyte activation and adhesion, in an attempt to develop potential neuroprotective agents. While these strategies have shown promise preclinically, clinical trials have yet to show clear benefit. Here, we review the current understanding of the pathophysiologic consequences of acute cerebral ischemic injury. Additionally, we discuss the role of the inflammatory cascade, with specific attention given to the deleterious role played by leukocyte activation and adhesion in stroke. Finally, relevant efforts to translate these basic science observations into clinical efficacy in acute stroke trials are critically reviewed.

The use of a mobile lithotripter in the treatment of tennis elbow and plantar fasciitis

OBJECTIVE

To evaluate the use of the mobile lithotripter in the treatment of tennis elbow and plantar fasciitis.

METHOD

A prospective single blind randomised trial was performed on 24 patients with tennis elbow and 23 patients with plantar fasciitis, with a mean duration of symptoms of 11 months. All patients had failed one or more method of treatment--conservative, topical non-steriodal anti-inflammatory drugs (NSAID), steroid injection and/or surgery. The patients were divided into treatment and placebo groups. The placebo group received treatment with a clasp on the elbow/heel to stop penetration of shock waves. A baseline pain score was obtained using the Million Visual Analogue scale (0-10). The affected area was infiltrated with 3-5mls of 1% lignocaine. The treatment consisted of 2000 shock waves at 2.5 bars of air pressure with a frequency of 8-10Hz. A total of three treatments were given at an interval of two weeks, each lasting for three to four minutes.

RESULTS

In the treatment groups, a final pain score at six months post treatment showed significant improvement (three or more points) in 78% of patients with tennis elbow and 93% of patients with plantar fasciitis. In the placebo groups, significant improvement was seen in one patient (9%) with tennis elbow. The other patients in the placebo groups did not show significant improvement. This was statistically significant (chi square test) for both conditions.

CONCLUSION

The mobile lithotripter is an effective way of treating tennis elbow and plantar fasciitis but warrants further larger studies.

A safe, simple and cost-effective protocol for blood transfusion in primary total knee replacement

BACKGROUND

Patients undergoing total knee replacement (TKR) in the UK usually have either blood cross-matched or have an auto-transfusion of drained blood postoperatively. A previous retrospective audit of blood requirements in patients who had undergone primary TKR showed that a large amount of cross-matched blood was wasted as the CT ratio (ratio of number of units of blood cross-matched to number of units transfused) of 4.9:1 was obtained. The range recommended by the Blood Transfusion Society is 2:1 to 3:1.

METHODS

A protocol was introduced to group and save plus antibody screen for all patients and to cross-match 2 units of blood pre-operatively in patients with either a haemoglobin of less than 12.5 g/dl or with multiple red cell antibodies in their blood. The trigger point for blood transfusion postoperatively was also reduced from 9.0 g/dl to 8.0 g/dl, unless the patient was clinically symptomatic.

RESULTS

A further prospective study involving 50 patients was carried out using the new protocol. Five patients required cross-matching pre-operatively, three with haemoglobin less than 12.5 g/dl and two with multiple red cell antibodies. Postoperatively, the patients with haemoglobin of less than 12.5 g/dl required blood transfusion of 2 units each, reducing the CT ratio to 1.7:1. The patients with red cell antibodies did not require a blood transfusion.

CONCLUSIONS

The benefits from above protocol are 2-fold: patient safety, as risks of transfusion are avoided; and cost saving, in regards to haematology technician time and auto-transfusion sets which cost around pound 70 each.

Contamination of surface soils, river water and sediments by trace metals from copper processing industry in the Churnet River Valley, Staffordshire, UK

The impacts of a functional and a demolished copper processing works on the aquatic and terrestrial environment in the vicinity of the works was investigated by determining the levels of selected trace metals in river water, river sediments, channel margin sediments and overbank soils. Samples were taken at five sites within an area of the Churnet Valley in Staffordshire, where the River Churnet flows through the two works. Analysis of river water samples by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) has shown that only copper is present above background levels considered to typify uncontaminated rivers. Analysis of river sediments, channel margin sediments and overbank soils by nitric-perchloric acid digestion and Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) analysis has indicated contamination by arsenic, cadmium and copper in the vicinity of both works. Arsenic and copper are deposited primarily within the aquatic environment, although some contamination of the terrestrial environment by copper is also observed. Cadmium is deposited primarily within the terrestrial environment. The deposition of arsenic and copper in river and channel margin sediments respectively is also related to current and historical contamination.

Mechanisms of copper tolerance by Armeria maritima in Dolfrwyong Bog, north Wales--initial studies

Preliminary field studies were carried out at Dolfrwynog Bog in July 2000. Replicate samples of water, Armeria maritima plants and the soils adhering to its roots were collected and analysed for copper. Concentrations of up to 6486 mg kg-1 of copper in the soils were recorded. Accumulation of copper by the plant as expressed by concentration factors (CF) show that it is acting mainly as a copper excluder. Of the copper that is taken up, most of it is retained within the roots with very little being transported to the shoots of the plant. Moreover, a further possible mechanism of tolerance is exhibited by the excretion of copper through its decaying leaves. Towards the use of in vitro cultures to study the copper tolerance mechanisms in A. maritima a micropropagation protocol has been developed. The ex vitro plants have been rooted and established in compost.

Therapeutic angiogenesis

Coronary artery disease remains the leading cause of morbidity and mortality in the Western world. The initial approach to treatment involves risk factor modification in an attempt to halt or slow the progression of disease. Treatment of symptomatic disease aims at reducing myocardial oxygen demand with medical therapy. When this fails, revascularization to restore blood supply by percutaneous coronary intervention or coronary artery bypass grafting is often necessary. Advances in medical technology have both increased the success rate and lowered the morbidity and mortality of these 2 procedures. However, a significant number of patients have diffuse coronary artery disease, absent conduits after previous bypass surgery, small distal vessels, and comorbidities that may preclude either procedure. In a recent analysis of 500 consecutive patients at a tertiary referral center, approximately 12% of these patients fell into this category (1). With the widespread use of revascularization, it is likely that the number of patients who will not be suitable for revascularization in the future will increase significantly. Therapeutic angiogenesis is an exciting new method of improving blood supply to an ischemic segment of the myocardium to provide symptomatic relief to a large and growing population of patients.

Idiopathic familial onychomadesis

Onychomadesis is defined as spontaneous separation of the nail plate from the nail bed, beginning at its proximal end and resulting in the shedding of the nail. It has been associated with a variety of clinical settings, including systemic illnesses, generalized skin diseases, and drug therapies. There have been a small number of reports in the older literature of idiopathic onychomadesis occurring in a familial pattern. We report the case of a healthy 12-year-old girl and her mother, both of whom have experienced recurrent onychomadesis affecting multiple digits, and in the absence of any causal disease or medication.

Negative regulation of male development in Caenorhabditis elegans by a protein-protein interaction between TRA-2A and FEM-3

The tra-2 gene of the nematode Caenorhabditis elegans encodes a predicted membrane protein, TRA-2A, that promotes XX hermaphrodite development. Genetic analysis suggests that tra-2 is a negative regulator of three genes that are required for male development: fem-1, fem-2, and fem-3. We report that the carboxy-terminal region of TRA-2A interacts specifically with FEM-3 in the yeast two-hybrid system and in vitro. Consistent with the idea that FEM-3 is a target of negative regulation, we find that excess FEM-3 can overcome the feminizing effect of tra-2 and cause widespread masculinization of XX somatic tissues. In turn, we show that the masculinizing effects of excess FEM-3 can be suppressed by overproduction of the carboxy-terminal domain of TRA-2A. A FEM-3 fragment that retains TRA-2A-binding activity can masculinize fem-3(+) animals, but not fem-3 mutants, suggesting that it is possible to release and to activate endogenous FEM-3 by titrating TRA-2A. We propose that TRA-2A prevents male development by interacting directly with FEM-3 and that a balance between the opposing activities of TRA-2A and FEM-3 determines sex-specific cell fates in somatic tissues. When the balance favors FEM-3, it acts through or with the other FEM proteins to promote male cell fates.

Mouse NKR-P1B, a novel NK1.1 antigen with inhibitory function

The mouse NK1.1 Ag originally defined as NK cell receptor (NKR)-P1C (CD161) mediates NK cell activation. Here, we show that another member of the mouse CD161 family, NKR-P1B, represents a novel NK1.1 Ag. In contrast to NKR-P1C, which functions as an activating receptor, NKR-P1B inhibits NK cell activation. Association of NKR-P1B with Src homology 2-containing protein tyrosine phosphatase-1 provides a molecular mechanism for this inhibition. The existence of these two NK1.1 Ags with opposite functions suggests a potential role for NKR-P1 molecules, such as those of the Ly-49 gene family, in regulating NK cell function.

Renal circulatory effects of adenosine in patients with chronic heart failure

OBJECTIVES

We sought to study the renal circulatory effects of adenosine in patients with chronic congestive heart failure (CHF).

BACKGROUND

Renal blood flow (RBF) is often reduced in patients with chronic CHF and may lead to decreased renal function. The cause of reduced RBF is multifactorial and involves systemic as well as local vasoregulatory mechanisms. Stimulation of renal adenosine A1 receptors in animal models has resulted in a significant vasoconstriction of afferent and efferent glomerular arterioles and deterioration of renal function. Although adenosine serum levels have been shown to be elevated in patients with CHF, their effect on the renal circulation in this patient population has not been studied.

METHODS

Nine patients with CHF from left ventricular systolic dysfunction were studied. The effects of adenosine at a dose of 10(-5) mol/liter infused directly into the main renal artery on heart rate, renal artery blood pressure, renal artery cross-sectional area (measured by intravascular ultrasound), renal Doppler blood flow velocity (measured by a Doppler flow wire in the renal artery), RBF and renal vascular resistance (RVR) were evaluated.

RESULTS

Infusion of adenosine resulted in no significant effect on heart rate or renal artery blood pressure but caused a substantial increase in RVR (11,204 +/- 1,469 to 31,494 +/- 3,911 dynes x s x cm(-5), p = 0.0005), which led to a marked fall in RBF in every patient (mean values 376 +/- 36 to 146 +/- 22 ml/m2, p = 0.0002). These changes in RVR and RBF were associated with no significant change in renal artery cross-sectional area (0.389 +/- 0.040 to 0.375 +/- 0.033 cm2, p = 0.3).

CONCLUSIONS

Stimulation of renal adenosine receptors in patients with CHF results in marked renal vasoconstriction that leads to an important reduction in RBF. Lack of change in renal artery cross-sectional area suggests that adenosine affects intrarenal resistance blood vessels rather than large conductance vessels. These results may indicate a rationale for investigation of renal adenosine receptor blockade for enhancement of RBF and improvement of renal function in patients with chronic CHF.

Modeling of oxygen transport in blood-perfluorocarbon emulsion mixtures: Part I: oxygen uptake in tubular vessels

Perfluorocarbon (PFC) emulsions are usually used as mixtures with blood to enhance its capacity for oxygen, because stand alone PFC emulsions cannot perform the normal regulatory functions of blood. These mixtures have been found to be very effective in increasing the tissue oxygen tension, especially at high oxygen partial pressures, and many experimental observations exist in the literature in support of this fact. The explanations for these observations are still speculative and unquantified, however. In this work, models have been developed to describe oxygen transport in uniform and non-uniform mixtures of blood and PFCs. For the latter case, the extreme situation of central migration of erythrocytes is considered, wherein the erythrocytes occupy the central core region of the vessel surrounded by a plasma annulus. The predictions of the proposed models have been examined using a fixed wall oxygen tension, and the oxygen transport characteristics of mixtures have been presented with reference to blood alone. It was found that at high oxygen tensions the addition of PFCs significantly increases the oxygen wall flux into the tube. This increased flux, coupled with effects of competing oxygen sinks (erythrocytes and PFC droplets), leads to an anomalous increase in the average oxygen tension for short distances from the tube entrance. It has been shown that a near wall excess of PFC droplets is not necessary to cause this increase, as mentioned by Vaslef and Goldstick. For longer distances, however, the addition of PFCs leads to a decrease in the average oxygen tension.

Modeling of oxygen transport in blood-perfluorocarbon emulsion mixtures: Part II: tissue oxygenation

The models developed in the accompanying article in this issue for oxygen transport in uniform (pseudo-homogeneous model) and non-uniform (core annulus model) dispersions of erythrocytes and perfluorocarbons (PFCs) have been analyzed with a fixed wall flux boundary condition. Such a situation arises in the case of oxygen transport from a capillary to the surrounding tissue. The results reveal that PFCs are extremely effective in increasing the tissue oxygen tension during enriched air breathing. The increased oxygen capacity of blood on the addition of PFC emulsion is the main contributor toward this increase. If the contribution of the accompanying increase in the arterial oxygen tension also is considered, the resulting increase in the tissue oxygen tension was even larger than that observed by Braun et al, and hence other factors, such as an increase in the cardiac output or service of erythrocyte free capillaries, need not be invoked. A near wall excess of PFC droplets, if it occurs, has been shown to have a negligible effect on the tissue oxygen tension during normal rates of tissue oxygen consumption when the intracapillary gradients are small. In these conditions, the capillary phase may be taken to be uniform. A criterion has been developed to assess the magnitude of the gradients within the capillary. Accordingly, in cases of elevated rates of tissue oxygen consumption or low arterial oxygen tensions, the internal gradients become important and the capillary phase can no longer be taken to be uniform.

Medea is a Drosophila Smad4 homolog that is differentially required to potentiate DPP responses

Mothers against dpp (Mad) mediates Decapentaplegic (DPP) signaling throughout Drosophila development. Here we demonstrate that Medea encodes a MAD-related protein that functions in DPP signaling. MEDEA is most similar to mammalian Smad4 and forms heteromeric complexes with MAD. Like dpp, Medea is essential for embryonic dorsal/ventral patterning. However, Mad is essential in the germline for oogenesis whereas Medea is dispensable. In the wing primordium, loss of Medea most severely affects regions receiving low DPP signal. MEDEA is localized in the cytoplasm, is not regulated by phosphorylation, and requires physical association with MAD for nuclear translocation. Furthermore, inactivating MEDEA mutations prevent nuclear translocation either by preventing interaction with MAD or by trapping MAD/MEDEA complexes in the cytosol. Thus MAD-mediated nuclear translocation is essential for MEDEA function. Together these data show that, while MAD is essential for mediating all DPP signals, heteromeric MAD/MEDEA complexes function to modify or enhance DPP responses. We propose that this provides a general model for Smad4/MEDEA function in signaling by the TGF-beta family.