Assessing the global burden of hemorrhage: The global blood supply, deficits, and potential solutions

There is a critical shortage of blood available for transfusion in many low- and middle-income countries. The consequences of this scarcity are dire, resulting in uncounted morbidity and mortality from trauma, obstetric hemorrhage, and pediatric anemias, among numerous other conditions. The process of collecting blood from a donor to administering it to a patient involves many facets from donor availability to blood processing to blood delivery. Each step faces particular challenges in low- and middle-income countries. Optimizing existing strategies and introducing new approaches will be imperative to ensure a safe and sufficient blood supply worldwide.

Self-assembly of 5,6-dihydroxyindole-2-carboxylic acid: polymorphism of a eumelanin building block on Au(111)

Investigating two-dimensional (2D) self-assembled structures of biological monomers governed by intermolecular interactions is a prerequisite to understand the self-assembly of more complex biomolecular systems. 5,6-Dihydroxyindole carboxylic acid (DHICA) is one of the building blocks of eumelanin - an irregular heteropolymer and the most common form of melanin which has potential applications in organic electronics and bioelectronics. By means of scanning tunneling microscopy, density functional theory and Monte Carlo calculations, we investigate DHICA molecular configurations and interactions underlying the multiple 2D patterns formed on Au(111). While DHICA self-assembled molecular networks (SAMNs) are dominated by the hydrogen bonding of carboxylic acid dimers, a variety of 2D architectures are formed due to the multiple weak interactions of the catechol group. The hydroxyl group also allows for redox reactions, caused by oxidation via O2 exposure, resulting in molecular rearrangement. The susceptibility of the molecules to oxidation is affected by their SAMNs architectures, giving insights on the reactivity of indoles as well as highlighting non-covalent assembly as an approach to guide selective oxidation reactions.

Room-temperature surface-assisted reactivity of a melanin precursor: silver metal-organic coordination versus covalent dimerization on gold

The ability of catecholamines to undergo oxidative self-polymerization provides an attractive route for preparation of coatings for biotechnology and biomedicine applications. However, efforts toward developing a complete understanding of the mechanism that underpins polymerization have been hindered by the multiple catechol crosslinking reaction pathways that occur during the reaction. Scanning tunneling microscopy allows the investigation of small molecules in a reduced-complexity environment, providing important insight into how the intermolecular forces drive the formation of supramolecular assemblies in a controlled setting. Capitalizing on this approach, we studied the self-assembly of 5,6-dihydroxy-indole (DHI) on Au(111) and Ag(111) to investigate the interactions that affect the two-dimensional growth mechanism and to elucidate the behavior of the catechol group on these two surfaces. X-ray photoelectron spectroscopy, together with density functional theory and Monte Carlo modeling, helps unravel the differences between the two systems. The molecules form large ordered domains, yet with completely different architectures. Our data reveal that some of the DHI molecules deposited on Ag are in a modified redox state, with their catechol group oxidized into quinone. On Ag(111), the molecules are deposited in long-range lamellar patterns stabilized by metal-organic coordination, while covalent dimer pairs are observed on Au(111). We also show that the oxidation susceptibility is affected by the substrate, with the DHI/Au remaining inert even after being exposed to O2 gas.

Transfer of CVD-grown graphene for room temperature gas sensors

An easy transfer procedure to obtain graphene-based gas sensing devices operating at room temperature (RT) is presented. Starting from chemical vapor deposition-grown graphene on copper foil, we obtained single layer graphene which could be transferred onto arbitrary substrates. In particular, we placed single layer graphene on top of a SiO₂/Si substrate with pre-patterned Pt electrodes to realize a chemiresistor gas sensor able to operate at RT. The responses to ammonia (10, 20, 30 ppm) and nitrogen dioxide (1, 2, 3 ppm) are shown at different values of relative humidity, in dark and under 254 nm UV light. In order to check the sensor selectivity, gas response has also been tested towards hydrogen, ethanol, acetone and carbon oxide. Finally, a model based on linear dispersion relation characteristic of graphene, which take into account humidity and UV light effects, has been proposed.

Reduced graphene oxide growth on 316L stainless steel for medical applications

We report a new method for the growth of reduced graphene oxide (rGO) on the 316L alloy of stainless steel (SS) and its relevance for biomedical applications. We demonstrate that electrochemical etching increases the concentration of metallic species on the surface and enables the growth of rGO. This result is supported through a combination of Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), density functional theory (DFT) calculations and static water contact angle measurements. Raman spectroscopy identifies the G and D bands for oxidized species of graphene at 1595 cm(-1) and 1350 cm(-1), respectively, and gives an ID/IG ratio of 1.2, indicating a moderate degree of oxidation. XPS shows -OH and -COOH groups in the rGO stoichiometry and static contact angle measurements confirm the wettability of rGO. SEM and AFM measurements were performed on different substrates before and after coronene treatment to confirm rGO growth. Cell viability studies reveal that these rGO coatings do not have toxic effects on mammalian cells, making this material suitable for biomedical and biotechnological applications.

Does circumpatellar electrocautery improve the outcome after total knee replacement?: a prospective, randomised, blinded controlled trial

The incidence of anterior knee pain following total knee replacement (TKR) is reported to be as high as 49%. The source of the pain is poorly understood but the soft tissues around the patella have been implicated. In theory circumferential electrocautery denervates the patella thereby reducing efferent pain signals. However, there is mixed evidence that this practice translates into improved outcomes. We aimed to investigate the clinical effect of intra-operative circumpatellar electrocautery in patients undergoing TKR using the LCS mobile bearing or Kinemax fixed bearing TKR. A total of 200 patients were randomised to receive either circumpatellar electrocautery (diathermy) or not (control). Patients were assessed by visual analogue scale (VAS) for anterior knee pain and Oxford knee score (OKS) pre-operatively and three months, six months and one year post-operatively. Patients and assessors were blinded. There were 91 patients in the diathermy group and 94 in the control. The mean VAS improvement at one year was 3.9 in both groups (control; -10 to 6, diathermy; -9 to 8, p < 0.001 in both cases, paired, two-tailed t-test). There was no significant difference in VAS between the groups at any other time. The mean OKS improvement was 17.7 points (0 to 34) in the intervention group and 16.6 (0 to 42) points in the control (p = 0.36). There was no significant difference between the two groups in OKS at any other time. We found no relevant effect of patellar electrocautery on either VAS anterior knee pain or OKS for patients undergoing LCS and Kinemax TKR.

Medical student surgery elective in rural Haiti: a novel approach to satisfying clerkship requirements while providing surgical care to an underserved population

BACKGROUND

The addition of global health programs to medical school training results in graduates with enhanced clinical skills and increased sensitivity to cost issues. Funding from U.S. medical schools has been unable to meet student demand, and therefore it is often a critical limiting factor to the lack of development of these programs. We describe an alternative approach for global health surgical training for medical students.

METHODS

Emory University medical students and faculty, in collaboration with Project Medishare for Haiti, planned, raised funds, and executed a successful short-term surgical camp to supplement available surgical services in rural Haiti. Learning objectives that satisfied Emory University School of Medicine surgery clerkship requirements were crafted, and third-year students received medical school credit for the trip.

RESULTS

In the absence of house staff and placed in an under-resourced, foreign clinical environment, the surgical elective described here succeeded in meeting learning objectives for a typical third-year surgical clerkship. Objectives were met through a determined effort to ensure that home institution requirements were aligned properly with learning activities while students were abroad and through a close collaboration between medical students, faculty members, and the administration.

CONCLUSIONS

Emory University's international surgery elective for medical students demonstrates that opportunities for supervised, independent student-learning and global health service can be integrated into a traditional surgical clerkship. These opportunities can be organized to meet the requirements and expectations for third-year surgery clerkships at other medical colleges. This work also identifies how such trips can be planned and executed in a manner that does not burden strained academic budgets with further demands on resources.

Enhancing resident interest in a state surgical meeting

OBJECTIVES

To stimulate increased interest in the annual American College of Surgery (ACS) chapter meeting, a state-wide mock oral examination for senior level surgical residents was organized. The purpose of this study was to evaluate the impact of and the results from our state's initial attempt to conduct a state-wide mock oral examination.

METHODS

The mock oral examination was structured as a 90-minute assessment in 9 content areas. Residents at or above the postgraduate year (PGY)-3 level were offered the examination and every attempt was made to ensure that examiners were from institutions different than the examinee's training program. Examinations were scored as satisfactory, marginal, or unsatisfactory. Each examinee received a written assessment of their performance.

RESULTS

Thirty-eight volunteer examiners committed to participate and 37 of the state's 82 senior-level residents appeared for the mock oral examination. The examiners included faculty from all 7 of the state's training programs and 10 private practice surgeons. The residents represented 6 of the 7 programs with 10 PGY-3, 12 PGY-4, and 15 PGY-5 residents completing the examination. The overall performance on the examination included 15 (40.5%) residents rated as satisfactory, 15 (40.5%) assessed as marginal, and 7 (18.9%) received a rating of unsatisfactory.

CONCLUSIONS

With rare exception, faculty examiners and resident examinees indicated by survey that the mock oral examination was a useful educational experience and increased the level of interest in attending the state's annual ACS meeting.

What is the optimal observation time for a penetrating wound to the flank?

Options for a hemodynamically stable patient with a penetrating wound to the flank or back but no peritonitis, includes serial physical examinations versus a triple-contrast CT scan. There is, however, little consensus on the minimum time for serial examinations to exclude an injury that requires an operation. Therefore, a retrospective review of patients who sustained a penetrating wound to the flank or back and were admitted to a Level I trauma center was performed. Patients were identified through the trauma registry, patient charts, and morbidity/mortality records. From 1995 to 2003, 93 patients undergoing observation for a penetrating flank/back wound subsequently required a therapeutic laparotomy. The time from admission to operation was less than 3 hours for 84 per cent of the patients requiring therapeutic intervention. A further 10 per cent presented with symptoms between 4 to 6 hours, and 6 per cent between 7 to 18 hours. All the injuries caused symptoms within 18 hours of the injury event. The majority of patients (94%) who require a laparotomy after a period of observation for a penetrating flank/back wound will develop signs and symptoms within 6 hours of admission. A period of hospitalization longer than 18 hours did not detect further injuries in the asymptomatic patient.

Nitrogen fertilizer impact on the Wilmot watershed aquifer in Prince Edward Island, Canada

The objective of this study is to estimate the soil N flux from the vadose zone to the aquifer of the Wilmot watershed (Prince Edward Island, Canada) for a typical three-year cropping rotation (barley-red clover-potato). A conceptual model estimates that 199-221 tons of N were yearly available for leaching at the watershed scale. A significant portion of this N amount was available for leaching at the end of the crop season representing 80-90% of the annual N balance. Drainage water nitrate concentrations were significantly higher after the potato-rotation year than during the crop season. Low nitrate concentrations were measured at spring thaw indicating that most of the nitrate available from the preceding potato crop season was likely leached at the end of fall or during winter. Early spring ionic exchange membrane sampling show a large availability of nitrate in soil possibly throughout winter as well, resulting from soil N mineralization and nitrification over the winter period. These findings are corroborated by the isotope natural abundance analysis of nitrate in groundwater implying that nitrifiers are significantly active during winter, as well as during the crop season, and that leaching of soil nitrates with seasonal signals takes place whenever recharge is occurring.

Tracheostomy in ventilator dependent trauma patients: a prospective, randomized intention-to-treat study

BACKGROUND

Tracheostomy is a commonly performed procedure in ventilator dependent patients. Many critical care practitioners believe that performing a tracheostomy early in the postinjury period decreases the length of ventilator dependence as well as having other benefits such as better patient tolerance and lower respiratory dead space. We conducted a randomized, prospective, single institution study comparing the length ventilator dependence in critically ill multiple trauma patients who were randomized to two different strategies for performance of a tracheostomy. We hypothesized that earlier tracheostomy would reduce the number of days of mechanical ventilation, frequency of pneumonia and length of intensive care unit (ICU) stay.

METHODS

Patients were eligible if they were older than 15 years and either a Glasgow Coma Score (GCS) >4 with a negative brain computed tomography (CT) (no anatomic head injury), or a GCS >9 with a positive head CT (known anatomic head injury). Patients who required tracheostomy for facial/neck injuries were excluded. Patients were randomized to an intention to treat strategy of tracheostomy placement before day 8 or after day 28.

RESULTS

The study was halted after the first interim analysis. There were 60 enrolled patients, who had comparable demographics between groups. There was no significant difference between groups in any outcome variable including length of ventilator support, pneumonia rate, or death.

CONCLUSION

A strategy of tracheostomy before day 8 postinjury in this group of trauma patients did not reduce the number of days of mechanical ventilation, frequency of pneumonia or ICU length of stay as compared with the group with a tracheostomy strategy involving the procedure at 28 days postinjury or more.

Predictors of mortality in trauma patients

The purpose of this study was to ascertain risk factors for death from trauma. The large cohort allows for simultaneous evaluation of known mortality risk factors along with controlling for factors to assess the influence of each independently. Individually, base deficit, temperature, hypotension, age, and injury severity have been shown to be associated with an increased risk of death. However, in the English literature, there is no data on the independent predictive power and interaction of these risk factors. A review of trauma registry parameters from 1995 to 2000 was used. Demographics, injury severity, physiological and hematological parameters, and time data were evaluated in a univariate analysis. Variables significantly associated with mortality were entered into a stepwise backward multiple logistic regression. There were 1276 deaths (8.9%) with 25 per cent of the deaths within 3 hours. The top four predictors of mortality in this group were partial thromboplastin time (OR 3.37, 95% CI: 2.51-4.52), positive head computed tomography result (OR, 2.47; 95% CI, 1.95-3.04), initial hemoglobin (OR, 1.69; 95% CI, 1.23-2.31), base deficit (OR, 1.62; 95% CI, 1.29-2.04), and trauma resuscitation bay systolic blood pressure (OR, 1.45; 95% CI, 1.11-1.88). We conclude that prognostic indicators of all-cause mortality after trauma, which remain independent in the presence of all other factors and are potentially treatable, included low hemoglobin, elevated prothrombin and partial thromboplastin time, low scene and trauma bay systolic pressure, and elevated base deficit. The independent indicators of mortality, which are untreatable, included head injury, increasing age, and Injury Severity Score.

Interleukin-7 levels may predict virological response in advanced HIV-1-infected patients receiving lopinavir/ritonavir-based therapy

OBJECTIVES

To examine the relationship between levels of the T-cell regulatory cytokine interleukin-7 (IL-7) and CD4 cell counts during immune reconstitution and to assess its prognostic value in advanced HIV-1-infected patients receiving lopinavir/ritonavir-based therapy.

METHODS

Thirty-six HIV-1-infected adults who completed 48 weeks of follow-up visits were included in this prospective study. Patients having failed two or more antiretroviral therapy regimens were treated with lopinavir/ritonavir-based therapy. An enzyme-linked immunosorbent assay was used to determine IL-7 plasma levels, flow cytometry was used to analyse cell surface antigens, and polymerase chain reaction was used to quantify plasma HIV-1.

RESULTS

Pretreatment IL-7 levels were elevated in all patients (mean 11.0 pg/mL) and were negatively correlated with CD4 cell counts and age (r=-0.59, P<0.001 and r=-0.57, P<0.001, respectively). During the course of treatment, IL-7 levels decreased by 34% while CD4 cell numbers progressively increased by 88%. Multivariate regression analysis showed that only pretreatment IL-7 levels predicted viral load at 48 weeks when controlling for baseline CD4 cell counts, viral load and patient demographics.

CONCLUSIONS

These findings are consistent with regulation of T-cell recovery by IL-7, and suggest that IL-7 measurements might be used to predict virological response.

Early injection of high-dose recombinant factor VIIa decreases blood loss and prolongs time from injury to death in experimental liver injury

BACKGROUND

Recombinant factor VIIa (rFVIIa) is used for treatment of bleeding episodes in hemophilia patients who develop inhibitors to factors VIII and IX. We tested the hypothesis that administration of rFVIIa early after injury would decrease bleeding and prolong the time from injury to death after experimental hepatic trauma.

METHODS

Anesthetized swine were cannulated for blood sampling and hemodynamic monitoring. Avulsion of the left median lobe of the liver induced uncontrolled hemorrhage. After a 10% reduction in mean arterial pressure, animals (n = 8 per group) were blindly randomized to receive intravenous rFVIIa 180 microg/kg, rFVIIa 720 microg/kg, or placebo. Pathologic examination of brain, lung, kidney, heart, and small bowel was performed to assess intravascular thrombosis. RESULTS Mortality during the first hour was 50% (four of eight) in controls versus 0% with rFVIIa 720 microg/kg (p = 0.02, chi2). Blood loss was decreased in the rFVIIa 720 microg/kg group versus the placebo group (13.2 +/- 5.5 mL/kg vs. 21.9 +/- 7.7 mL/kg;p = 0.0223). Time from injury to death was significantly prolonged in the rFVIIa 720 microg/kg group compared with placebo (116 minutes vs. 8.5 +/- 3.5 minutes; p= 0.02). No macro- or microthrombi in vital organs were identified on pathologic examination.

CONCLUSION

Intravenous administration of high-dose rFVIIa early after induction of hemorrhage decreased bleeding and prolonged survival. No evidence of thrombosis in vital organs was observed.

Programs for the promotion of family wellness and the prevention of child maltreatment: a meta-analytic review

OBJECTIVE

The objectives were to determine the effectiveness of programs in promoting family wellness and preventing child maltreatment and to identify factors that moderate program success.

METHOD

Meta-analysis, employing a 3-step model testing procedure, was used to review 56 programs designed to promote family wellness and prevent child maltreatment.

RESULTS

The effect sizes for proactive interventions were larger at follow-up than at post-assessment, while the effect sizes for reactive interventions were higher at post-assessment than follow-up. The lowest effect sizes for home visitation programs on child maltreatment were for programs with 12 or fewer visits and less than a 6-month duration. Intensive family preservation programs with high levels of participant involvement, an empowerment/strengths-based approach, and a component of social support had higher effect sizes than programs without those elements. Also, both home visitation and intensive family preservation interventions achieved higher effect sizes with participants of mixed socioeconomic status (SES) than participants with low SES.

CONCLUSIONS

The total mean weighted effect size was .41, indicating that outcomes for the intervention group exceed 66% of those in control/comparison groups. The findings from this review demonstrated that child maltreatment can be prevented and that family wellness can be promoted.

Evaluation of polyethylene terephthalate for ABO and Rh typing and alloantibody screening

BACKGROUND

For many years, hospitals and laboratories have used evacuated glass tubes for blood collection. To improve the safety of blood collection, plastic polyethylene terephthalate (PET) tubes (Vacutainer PLUS, Becton Dickinson) have been developed. The objectives of this study were to compare the accuracy of ABO grouping, Rh typing, and antibody screening of blood samples collected in plastic tubes with that in glass tubes and to determine if refrigerated blood samples collected in plastic tubes remained stable over a 28-day period.

STUDY DESIGN AND METHODS

Samples were collected from 121 volunteers, at least 30 from each of the A, B, O, and AB blood groups, in four types of Vacutainer tubes: silica-coated plastic, K(2) EDTA plastic, uncoated glass, and K(2) EDTA glass. Samples from each tube were tested for ABO group and Rh type by use of the microtyping gel identification card system and the tube method. A three-cell antibody screen was performed by the microtyping gel card technique with a monospecific IgG reagent. Initial samples were tested within 3 hours of collection. Refrigerated samples were retested for ABO and Rh type and antibody screening 1, 2, 21, and 28 days later. Agreement between test results was determined by using Cohen's Kappa statistic.

RESULTS

Complete agreement was observed between the ABO and Rh typing results in samples drawn into glass and plastic tubes of both the EDTA and nonanticoagulated type (kappa = 1.0). In retesting, there were no examples of a change in ABO or Rh type over the 28-day study period. Only two alloantibodies (1.7%) were identified in the 121 samples, and no difference was observed in alloantibody expression in either plastic or glass Vacutainer tubes over the 28-day study period.

CONCLUSION

Samples collected into the PET serum or EDTA tubes provided accurate ABO and Rh typing results that remained consistent over a 28-day period. Samples collected in these tubes also appeared to enable accurate alloantibody identification. However, the number of alloantibodies identified in this study was small, and this result should be confirmed in a larger series.

Retrospective follow-up of maternal deaths and their associated risk factors in a rural district of Tanzania

OBJECTIVE

To determine the maternal mortality rate in a rural district of Tanzania and to measure the incidence of causes of maternal mortality, the presence of risk factors and the relationship with social and demographic factors.

METHOD

From January to December 1993 a retrospective recording of maternal deaths was completed using verbal autopsy and networking.

RESULTS

A total of 76 deaths were found which is equivalent to a maternal mortality ratio of 961 per 100,000 live births for this 12-month period of time. The leading causes of death were postpartum haemorrhage with retained placenta, anaemia, postpartum haemorrhage without retained placenta, AIDS complex and obstructed labour (in descending order of frequency). Maternal deaths were seen irrespective of group factors such as access to a main road, presence of antenatal risk factors and contact with health care personnel or a nearby facility before death. Mortality was also present both in home and hospital deliveries (excluding hospital referrals). Antenatal care had been received by 97.2% of the mothers who died after the second trimester. The referral rate even in the presence of a known antenatal risk factor was 34.6%. Patient compliance to the referral was only 44.4%. Mothers and their families followed strong cultural beliefs even when they were detrimental to the mother's health. Maternal deaths were proportionately higher among women > 40 who were also gravid > or = 5, but there was no significant increase in deaths in women < 19 years of age.

CONCLUSION

Effective antenatal care, appropriate emergency treatment of complications, access to transportation and competent referral level care with adequate equipment encompass the most effective answers to reduction of maternal deaths at a district level.

Community based studies on childhood mortality in a malaria holoendemic area on the Tanzanian coast

Demographic surveillance of children under 5 years of age was undertaken over a 2 year period in a rural area of coastal Tanzania where holoendemic malaria conditions exist. The mean annual entomological innoculation rate (EIR) during the period under study was 234 infective bites per person. There were 192 deaths in children and 1130 live births during the 2 years. Of these, 148 were infant deaths giving an infant mortality rate of 131/1000 live births (95% CI 101, 154). There were 44 deaths in children 1-4 years of age and the overall child mortality rate was 10/1000 (95% CI 6.1, 14.3). Using verbal autopsy questionnaires, 56% of the deaths under 4 years were tentatively attributed to malaria.

A hermeneutic analysis of the lived experiences of associate nurses

In order to understand better the role of associate nurse in the primary nursing model, narratives from associate nurses were analysed using hermeneutic approach. Major themes in the narratives included: connecting with patients, collaborating with other nurses, and making decisions. Associate nurses were found to define their practice as 'primary' in terms of their contributions to patient care and being a responsible professional. A better understanding of the associate role in clinical practice can enhance patient care and professional relationships. Further research into the philosophical nature of primary nursing is suggested.

Backache and epidural analgesia

A questionnaire was sent to 2065 mothers 1 year after delivery as part of a larger study into patient satisfaction with all aspects of their obstetric care. The response rate adjusted for non-delivered mail was 67.1%. There was a high incidence of new long-term backache in mothers who had received epidural analgesia (26.2% at one year) compared to the mothers who had not (1.7%). Further analysis of the data revealed no other significant associated factor.

Spectroscopic characterization of heme A reconstituted myoglobin

The focus of this study was to examine the functional role of the unusual peripheral substitution of heme A. The effects of heme A stereochemistry on the reconstitution of the porphyrin have been examined in the heme A-apo-myoglobin complex using optical absorption and resonance Raman and electron paramagnetic resonance spectroscopies. The addition of one equivalent of heme A to apo-Mb produces a complex which displays spectroscopic signals consistent with a distribution of high- and low-spin heme chromophores. These results indicate that the incorporation of heme A into apo-Mb significantly perturbs the protein refolding.

Mass spectrometric detection of cross-linked fatty acids formed during radical-induced lesion of lipid membranes

A mass spectrometric method is described for the quantitative determination of dimers of polyunsaturated fatty acids (PUFA) formed in the hepatic endoplasmic reticulum of rats upon inhalation of tetrachloromethane. The results show that dimers account for a considerable fraction of microsomal PUFA which disappear during CCl4 metabolism. Cross-linking of the membrane lipids of the endoplasmic reticulum seems to be a significant process with respect to cell toxicity.

Biochemical and immunological characterization of the flagellar-associated regulatory subunit of a type II cyclic adenosine 5'-monophosphate-dependent protein kinase

We have shown previously that the regulatory subunit (RII) of a type II cyclic AMP (cAMP)-dependent protein kinase is tightly associated with mammalian sperm flagella (J. A. Horowitz et al. (1984) J. Biol. Chem. 259, 832-838; J. A. Horowitz et al. (1988) J. Biol. Chem. 263, 2098-2104). In the present study the flagellar RII was compared to other well-characterized RIIs using biochemical and immunological methods. Flagellar polypeptides were screened by immunoblot analysis with monoclonal antibodies directed against the RII alpha and RII beta isoforms. An RII beta monoclonal antibody failed to cross-react with any flagellar polypeptide. In contrast, mAB 622, an RII alpha/RII beta monoclonal antibody, cross-reacted with a 57,000 Da polypeptide. However, another RII alpha/RII beta monoclonal antibody interacted weakly with the flagellar RII, suggesting that the epitope for this antibody is modified in flagellar RII. Partial peptide mapping of 8-azido-[32P]cAMP-labeled RIIs revealed that although heart and testis generated similar fragmentation patterns, there were differences in the maps from flagellar RII. Two-dimensional sodium dodecyl sulfate-gel electrophoresis of 8-azido-[32P]cAMP-labeled RII from rat flagella and bovine heart showed that the former possessed a considerably more acidic isoelectric point. Partial proteolysis of the flagellar RII by either endogenous or exogenous proteases resulted in the cleavage of RII to a 40,000 Mr fragment. Complete release of this fragment from the flagellum was achieved if proteolysis was performed in the presence of thiol reducing agents. In their absence, approximately 50% of the fragment remained bound to the flagellum. The soluble proteolytic fragment was shown to be monomeric by native high-resolution gel-permeation chromatography and contained a functional cAMP-binding site(s).

Immunogold localization of the regulatory subunit of a type II cAMP-dependent protein kinase tightly associated with mammalian sperm flagella

We have shown previously that the regulatory subunit (RII) of a type II cAMP-dependent protein kinase is an integral component of the mammalian sperm flagellum (Horowitz, J.A., H. Toeg, and G.A. Orr. 1984. J. Biol. Chem. 259:832-838; Horowitz, J.A., W. Wasco, M. Leiser, and G.A. Orr. 1988. J. Biol. Chem. 263:2098-2104). The subcellular localization of this flagellum-associated RII in bovine caudal epididymal sperm was analyzed at electron microscope resolution with gold-conjugated secondary antibody labeling techniques using anti-RII monoclonal antibodies. By immunoblot analysis, the flagellum-associated RII was shown to interact with mAb 622 which cross reacts with both neural and nonneural isoforms of RII. In contrast, a neural specific monoclonal antibody (mAb 526) failed to interact with flagellar RII. In the midpiece of the demembranated sperm tail, gold label after mAb 622 incubation was primarily associated with the outer mitochondrial membrane. Although almost all specific labeling in the midpiece can be assigned to the mitochondria, in the principal piece, there is some labeling of the fibrous sheath. Labeling of the outer dense fibers and the axoneme was sparse. Specific labeling was virtually absent in the sperm head. Sections of sperm tails incubated in the absence of primary antisera or with mAb 526 showed little labeling. A beta-tubulin monoclonal antibody localized only to the 9 + 2 axoneme. These results raise the possibility that a type II cAMP-dependent protein kinase located at the outer mitochondrial membrane plays a role in the direct cAMP stimulation of mitochondrial respiration during sperm activation.

Major 56,000-dalton, soluble phosphoprotein present in bovine sperm is the regulatory subunit of a type II cAMP-dependent protein kinase

It has been shown that cAMP-dependent phosphorylation of a soluble sperm protein is important for the initiation of flagellar motion. The suggestion has been made that this motility initiation protein, named axokinin, is the major 56,000-dalton phosphoprotein present in both dog sperm and in other cells containing axokinin-like activity. Since the regulatory subunit of a type II cAMP-dependent protein kinase is a ubiquitous cAMP-dependent phosphoprotein of similar subunit molecular weight as reported for axokinin, we have addressed the question of how many soluble 56,000-dalton cAMP-dependent phosphoproteins are present in mammalian sperm. We report that in bovine sperm cytosol, the ratio of the type I to type II cAMP-dependent protein kinase is approximately 1:1. The type II regulatory subunit is related to the non-neural form of the enzyme and undergoes a phosphorylation-dependent electrophoretic mobility shift. The apparent subunit molecular weights of the phospho and dephospho forms are 56,000 and 54,000 daltons, respectively. When bovine sperm cytosol or detergent extracts are phosphorylated in the presence of catalytic subunits, two major proteins are phosphorylated and have subunit molecular weights of 56,000 and 40,000 daltons. If, however, the type II regulatory subunit (RII) is quantitatively removed from these extracts using either immobilized cAMP or an anti-RII monoclonal affinity column, the ability to phosphorylate the 56,000- but not 40,000-dalton polypeptide is lost. These data suggest that the major 56,000 dalton cAMP-dependent phosphoprotein present in bovine sperm is the regulatory subunit of a type II cAMP-dependent protein kinase and not the motility initiator protein, axokinin.

Adaptation of colonic uptake of hexoses and lipids following ileal resection: effect of variations in the fat content of the diet

This study was undertaken to determine the effect of varying the dietary composition of fat (corn oil and lard) on the colonic uptake of lipids (medium-chain-length fatty acids, cholesterol and decanol) and hexoses (D-glucose, galactose and 3-O-methyl glucose) in control rabbits with an intact intestinal tract, and in animals submitted 6 weeks previously to the surgical removal of the distal half of their small intestine. Food intake was similar in the control and resected animals fed the high-fat (HF) or the low-fat (LF) diet. Body weight gain was lower in control animals fed LF than HF, but was lower in resected animals fed HF than LF. Colonic adherent mucosal fluid volume was unaffected by diet or by ileal resection, but colonic weight was lower in resected than control animals fed LF. Colonic uptake of glucose and 3-O-methyl glucose but not galactose was changed by ileal resection and by dietary fat changes. Colonic uptake of fatty acids and cholesterol was also different in HF than LF, and in resected as compared with control animals, but these changes were not explained by variations in the effective resistance of the colonic unstirred water layer. Thus colonic transport function is altered by the manipulation of the dietary content of fat and by resection of the ileum.

Uptake of hexoses and lipids into rabbit jejunum and colon following ileal resection: effect of variations in the cholesterol and fat content of the diet

After 6 weeks feeding on either a high-cholesterol/fat (H) or a low-cholesterol/fat (L) diet, jejunal and colonic uptake was measured using a previously validated in vitro technique in control rabbits with an intact intestinal tract (C) and in animals submitted to the surgical removal of the distal half of the small intestine (R). The uptake of hexoses and fatty acids was influenced by ileal resection and by diet. Dietary manipulation altered the passive and active transport properties of the intestine and had a different effect on intestinal transport in animals with an ileal resection than in animals with an intact small intestine.