Reducing delamination of an electron-transporting polymer from a metal oxide for electrochemical applications

Delamination of the electron-transporting polymer N2200 from indium tin oxide (ITO) in aqueous electrolytes is mitigated by modifying ITO with an azide-functionalized phosphonic acid (PA) which, upon UV irradiation, reacts with the polymer. The optical, electrochemical, and spectroelectrochemical properties of N2200 thin films are retained in aqueous and non-aqueous media.

Maximizing Vanadium Deployment in Redox Flow Batteries Through Chelation

By tailoring the coordination sphere of vanadium to accommodate a 7-coordinate geometry, a highly soluble (>1.3 M) and reducing (-1.2 V vs Ag/AgCl) flow battery electrolyte is generated from [V(DTPA)]^2-/3- (DTPA = diethylenetriaminepentaacetate). Bulk spectroelectrochemistry is performed in situ to assess material properties in both oxidized and reduced states. Flow batteries are assembled in near neutral pH conditions and operated with discharge energy densities of 12.5 Wh L^-1 and high efficiency. Further, the first chelated flow battery using the same aminopolycarboxylate ligand for both electrolytes is generated. The presented batteries demonstrate comparable performance to the iron-vanadium and all-vanadium flow batteries while doubling the effective discharge energy of vanadium (Wh per mol V) and minimizing safety and operating risks, offering grid-scale energy storage alternatives.

Arthroscopic diagnosis and medical management of calcium pyrophosphate deposition disease in the temporomandibular joint

Calcium pyrophosphate deposition disease (CPPD) is a crystal arthropathy that can involve the temporomandibular joint. It is known to accelerate the osteoarthritic process, often initially presenting with advanced level of disease. The management of CPPD in the rheumatology and orthopedic literature is one of early diagnosis and medical management of acute attacks. The cases of three patients who presented with initial complaints of joint pain and limited mouth opening are presented. Preoperative imaging identified calcifications in two of these patients. Definitive diagnosis was achieved through arthroscopic-assisted biopsy. Rheumatology referrals revealed chondrocalcinosis of the knee in one patient. All patients had improved mouth opening and pain.

New technique for removing bone covering miniplates and screws

Miniplate osteosynthesis has revolutionised the treatment of open reduction and internal fixation in craniomaxillofacial procedures. However, when complications arise necessitating the removal of previously placed miniplates, bony overgrowth may be present and must be eliminated before removal of the hardware is possible. Osteogenesis over the screws prevents proper engagement of the screwdriver with the screw drives. If bone remains embedded in the screw drive during attempted removal of the screw, the contact interference increases the risk of the screwdriver slipping and the screw drive being stripped. There remains a lack of adequate techniques to clear bony overgrowth from miniplates and screws to allow for easy removal, as conventional methods are ineffective, time-consuming, and may damage the screw drives. Herein, we describe a new laser-assisted miniplate removal technique to eliminate bone that has grown over miniplates and screws before the miniplate is removed. This technique is efficient, safe, and simple and, compared with conventional methods, may decrease the complications associated with the removal of miniplates and screws.

Food allergies developing after solid organ transplant

The development of food allergy is an increasingly recognized form of morbidity after solid organ transplant. It occurs more commonly in liver transplant recipients, although it has also been reported in heart, lung, kidney, and intestinal transplants. Pediatric transplant recipients are more likely to develop symptoms compared to adults, and reports of frequency vary widely from 5% to 38% in pediatric liver transplant recipients. Multiple mechanisms have been proposed in the literature, although no single mechanism can yet account for all reported observations. As food allergy can have at worst potentially fatal consequences, and at best require lifestyle adjustment through food avoidance, it is important for recipients to be aware of the donor's food allergies and particularly in pediatrics, the possibility of completely de novo allergies. This review explores the recent reports surrounding food allergy after solid organ transplant, including epidemiology, proposed mechanisms, and implications for practice.

Presentation of atopic disease in a large cohort of pediatric liver transplant recipients

Atopic disease occurs in solid organ transplant recipients with an increasingly recognized frequency. The time course for the development of these atopic diseases in liver transplantation has not been described. The objective was to characterize the atopic manifestations of children receiving chronic immunosuppression after orthotopic liver transplantation (OLT). Chart review and follow-up questionnaire were utilized for 176 OLT pediatric recipients at a single institution for manifestations of allergic disease. Atopic disease was present in 25 (14.2%) patients. Median age at transplant was 16 months with a median follow-up of 63 months. Food allergy and non-food related atopic symptoms presented at a median of 11.5 (IQR, 6-28) and 19 (IQR, 5-41) months post-transplantation, respectively. The median age at transplant of the non-atopic children was 72 months, higher than patients with atopy (p < 0.001). Food allergy and atopic skin disease symptoms were present in 40% and 56% of cases, respectively. Asthma, allergic rhinitis, or both were found in 66% of cases. The onset of symptoms of food allergy and eczema (median, 12 months post-transplantation) preceded symptoms of allergic rhinitis and asthma. (median of 27 and 30 months post-transplantation, respectively). Atopy occurs in ∼14% of pediatric liver transplant recipients, with manifestations including food allergy, eczema, allergic rhinitis, and asthma.

Mechanism of the sex difference in neuronal ischemic cell death

BACKGROUND

Stroke risk and outcome are different in men and women. We hypothesized that this is partly due to an inherent difference in susceptibility to ischemia between neurons from male vs. female brains. We tested whether neurons from male rodents are more susceptible to in-vitro ischemia than cells from females, and if this is related to increased expression of soluble epoxide hydrolase (sEH). sEH contributes to neuronal cell death by inactivating neuroprotective epoxyeicosatrienoic acids (EETs).

METHODS

Rodent cortical neurons were cultured, and exposed to oxygen-glucose deprivation (OGD); then cell death was measured. EETs levels were determined by LC-MS/MS. Expression of sEH-encoding ephx2 was determined by qRT-PCR. Western blotting, immunocytochemistry, and hydrolase activity assay assessed protein expression and activity.

RESULTS

Cell death after OGD was higher in neurons from males vs. females, which correlated with higher ephx2 mRNA and stronger sEH immunoreactivity. However, EETs levels were similar in both sexes and pharmacological inhibition of the hydrolase domain of sEH did not abolish the sex difference in cell death. Genetic knockout of sEH in mice abolished the sex difference observed in neurons isolated from these mice after OGD.

CONCLUSIONS

Cultured cortical neurons from females are more resistant to ischemia than neurons from males. Neurons from females have less sEH activity compared to neurons from males at baseline, although sEH levels were not measured after OGD. While pharmacological inhibition of the hydrolase domain of sEH does not affect cell death, knockout of the gene encoding sEH eradicates the sex difference seen in wild-type neurons, suggesting a role for further study of the lesser-known phosphatase domain of sEH and its role in sexual dimorphism in neuronal sensitivity to ischemia.

Lentiviral transduction of human T-lymphocytes with a RANTES intrakine inhibits human immunodeficiency virus type 1 infection

Intrakines, modified intracellular chemokines, offer a novel strategy to prevent cellular entry of HIV-1 by blocking the surface expression of HIV-1 co-receptors. To investigate potential clinical applications of the RANTES-intrakine, we explored the use of HIV-1-based lentiviral vectors for therapeutic gene transfer into T-lymphocytes. RANTES-intrakine genes can be efficiently transduced into primary human T-lymphocytes by lentiviral vectors, especially when human T-lymphocytes were stimulated with CD3 and CD28 antibodies. The transduced T cells showed decreased surface expression of the chemokine receptor CCR-5, as well as CCR-1 and CCR-3. This lentivirus-mediated approach to intrakine gene transfer protected human T-lymphocytes from infection by a variety of R5-tropic HIV-1 strains. A quantitative real-time PCR assay, developed to monitor cells for HIV entry and persistence, revealed persistent low copy numbers of proviral HIV DNA in RANTES intrakine-transduced T-lymphocytes during 3-week culture, suggesting that viruses produced from infected untransduced cell populations were unable to infect the surrounding transduced T-lymphocytes. We conclude that targeting HIV-1 co-receptors to block virus entry with lentiviral vectors is an attractive approach to the control of HIV-1 infection.

Mechanics of solid tissue invasion by the mammalian pathogen Pythium insidiosum

The relative significance of mechanical penetration versus the action of substrate-degrading enzymes during solid tissue invasion has not been established for any fungal disease. Pythium insidiosum is an oomycete fungus (or stramenopile) that causes a rare, but potentially lethal infection in humans and other mammalian hosts. Experiments with miniature strain gauges showed that single hyphal apices of this pathogen exert forces of up to 6.9 microN, corresponding to maximum pressures of 0.3 microN microm(-2) or MPa. Samples of cutaneous and subcutaneous tissue from fresh human cadavers displayed a mean strength (resistance to needle puncture) of 24 microN microm(-2), and a mean pressure of 30 microN microm(-2) was necessary to penetrate skin strips from slaughtered horses. These experiments demonstrate that P. insidiosum does not exert sufficient pressure to penetrate undamaged skin by mechanics alone, but must effect a decisive reduction in tissue strength by proteinase secretion.

Prevalence and incidence studies of pressure ulcers in two long-term care facilities in Canada

A study was initiated to determine the prevalence and incidence of pressure ulcers in two long-term care facilities in Canada, one with 95 residents and the other with 92 residents. The prevalence study was conducted at both facilities on a single day. The incidence study was completed after 41 and 42 days, respectively, at each facility. Data were collected on demographics, medical information, and possible contributing factors. Each resident was assessed for the presence of a pressure ulcer. Each ulcer was staged and anatomical location was noted. The prevalence of pressure ulcers in the two long-term care facilities was 36.8% and 53.2%, respectively. The incidence of pressure ulcers in the two long-term care facilities was 11.7% and 11.6%, respectively. In conclusion, the pressure ulcer prevalence is higher than published figures for the long-term care setting. However, a pressure ulcer incidence of less than 12% in each facility suggests an equal and acceptable level of nursing care in both facilities. The disparity of pressure ulcer prevalence between the two facilities may be explained by a difference of case mix.

Radiation-induced cytogenetic instability in vivo

Radiation-induced cytogenetic instability has been well documented in a number of laboratories, and we have hypothesized that such instability is the initiating event in the process leading to radiation-induced cancer. To date most studies of radiation-induced instability have used systems in which cells are rapidly dividing. For this phenomenon to have significance for radiation carcinogenesis, it must be established that instability can be induced in vivo in less rapidly dividing fully differentiated tissues known to be at risk. In the present study, we have examined the kinetics of radiation-induced cytogenetic instability in mammary epithelial cells after irradiation in vivo. Having established that instability could arise in vivo in intact mammary tissue, we subsequently demonstrated a dose-response relationship both in vitro and in vivo and demonstrated a lower frequency of instability after fractionated exposures.

Disparities of health in African Americans

As a cohort of the vulnerable populations, African Americans have the poorest health status indicators of all ethnic groups. Using a vulnerable populations theoretical framework, the reasons for the disparities are discussed.

Isolation of the PufX protein from Rhodobacter capsulatus and Rhodobacter sphaeroides: evidence for its interaction with the alpha-polypeptide of the core light-harvesting complex

Using mutant strains of Rhodobacter capsulatus and Rhodobacter sphaeroides in which the pufX gene had been deleted, it was possible to identify by HPLC membrane protein components present in pufX+ cells but absent in pufX- cells. In parallel preparations, membrane proteins soluble in chloroform/methanol containing ammonium acetate were first extracted from lyophilized membrane fractions of the pufX+ cells and separated from pigments and larger protein material by gel-filtration chromatography. Protein-containing fractions were examined by HPLC, and several peaks were collected from pufX+ material that were not present in pufX- material. From N-terminal amino acid sequencing, the PufX protein of Rb. capsulatus was identified, and from positive interaction with a PufX protein antibody, the Rb. sphaeroides PufX protein was identified. Although overall yields were very small, sufficient quantities of these proteins were isolated to evaluate their effect on the reconstitution of the core light-havesting antenna (LH1) and its subunit complex. From the behavior of the PufX protein and the alpha-polypeptide of LH1 on HPLC, qualitative evidence was obtained that the two proteins have a high affinity for each other. In reconstitution assays with bacteriochlorophyll (Bchl) and the LH1 alpha- and beta-polypeptides of Rb. capsulatus, the PufX protein of Rb. capsulatus was inhibitory to LH1 formation at low concentration. A similar inhibition was exhibited by Rb. sphaeroides PufX protein for reconstitution of LH1 with Bchl and the LH1 alpha- and beta-polypeptides of Rb. sphaeroides. In both cases, the ratios of concentrations of the PufX protein to the alpha-polypeptide causing 50% inhibition were approximately 0.5. Formation of the heterologous (alpha beta) subunit-type complex formed with Bchl and the alpha- and beta-polypeptides of LH1 of Rb. capsulatus was also inhibited by low concentrations of the Rb. capsulatus PufX protein (approximately 50% inhibition at PufX:alpha-polypeptide ratios = 0.5). However, neither PufX protein inhibited formation of a homologous (beta beta) subunit-type complex, which indicates that the PufX proteins do not interact with the beta-polypeptides.

Secretory phospholipase A2 cleavage of intravasated bone marrow primes human neutrophils

BACKGROUND

Recent clinical reports suggest that early femoral intramedullary rod (IMR) fixation in patients with multiple injuries increases the risk of adult respiratory distress syndrome (ARDS). We have shown that lipid-mediated neutrophil (PMN) priming and elevated circulating levels of secretory phospholipase A2 (sPLA2) within the first 24 hours after injury correlate with the development of ARDS. We thus hypothesized that circulating lipid products, generated by sPLA2 cleavage of intravasated bone marrow, prime PMNs for enhanced superoxide anion (O2-) production.

METHODS

Isolated PMNs from healthy volunteers were incubated for 5 minutes with buffer or sPLA2-lysed bone marrow (100 U/mL) collected from trauma patients. After formyl-methionyleucylphenylalanine (fMLP) activation, O2- production was quantified by the superoxide dismutase-inhibitable reduction of cytochrome c. Blood samples were also drawn from five injured patients before and 24 hours after femoral IMR fixation. PMNs were isolated and assessed for in vivo priming.

RESULTS

PMNs incubated with sPLA2-lysed bone marrow were primed for more than 3.5 times greater fMLP-induced O2- production. Furthermore, in patients with femoral fractures, PMN O2- release in response to fMLP after IMR fixation was more than 2.5 times higher than before fixation.

CONCLUSION

Collectively, the findings suggest that bone marrow released from acute fracture sites may become a lipid substrate for the elevated sPLA2 levels found in injured patients. The resultant priming of PMNs may thus render the injured patient at risk for ARDS. Although clearly hypothetical at present, we submit that these observations warrant further investigation because of their clinical implications.

Triazolam impairs delayed recall but not acquisition of various everyday memory tasks in humans

A double-blind test battery was administered to 24 human subjects (8 control, 16 drug) to assess the effects of 0.125 mg triazolam (oral) on memory encoding and retention across delay intervals ranging from seconds to 1 week after presentation. Although the drug reduced immediate psychomotor performance, it did not impair recall of previously learned information, nor did it significantly impair encoding of new information. The drug enhanced immediate recall of the location and identity of playing cards, without affecting 4-h delayed recall. The drug treatment impaired correct recall of object names after a delay of 20 min. At 4 h delay, the drug impaired olfactory recognition and free-recall of object names. At both 1 day and 1 week delay, the drug impaired recall of biographical information and correct identification of picture-photographer pair associations. The drug also impaired the daily improvement of the drug group as compared with the control group in a geometric puzzle solving task. The time course of these memory impairments compares well with the known effects of triazolam on long-term potentiation (LTP), a candidate biological mechanism underlying telencephalic memory formation and expression.

Dissemination and implementation of Put Prevention into Family Practice

INTRODUCTION

The Put Prevention into Practice (PPIP) program was developed and disseminated to address patient, clinician, and office barriers that result in less than optimal delivery of preventive services in the United States.

METHODS

To study the dissemination of PPIP by the American Academy of Family Physicians (AAFP), pre- and post-dissemination surveys of knowledge about PPIP and purchase order data were obtained from the AAFP. In addition, a mail questionnaire was sent to a random sample of purchasers to study their use of PPIP.

RESULTS

After two years of active promotion, 27% of AAFP members had heard about PPIP, and PPIP components were purchased by 2,004 individuals during its inital dissemination. Flow sheets, health guides, exam room wall charts, and the Clinician's Handbook of Preventive Services were the PPIP items most frequently purchased and used. Excluding the Clinician's Handbook of Preventive Services, 58% of purchasers used one or more parts of the kit with an average of less than four items used per purchaser.

CONCLUSIONS

Initial dissemination and implementation of PPIP among family physicians was limited; continued promotion will likely improve dissemination of PPIP. However, this study, and others suggest that the simple availability of a kit of materials is not sufficient to enhance the delivery of preventive services as envisioned by clinicians or policy makers. Additional strategies for dissemination and implementation of preventive services will be required, such as providing external consultation services to practices, incorporation of preventive services into HMO organizations, and training of residents in strategies for change in their future practices.

A profile of the behavioral changes produced by facilitation of AMPA-type glutamate receptors

A newly developed group of benzoylpiperidine drugs that enhance AMPA-receptor-gated currents ("ampakines") has been shown to improve memory encoding in rats across a variety of experimental paradigms. The present experiments were intended to i) provide a partial profile of the behavioral changes produced by ampakines, ii) test if two ampakines (BDP-12 and BDP-20) that differ significantly in their effects on AMPA receptor kinetics produce similar behavioral profiles, and iii) determine if physiological potency is reflected in behavioral potency. BDP-20 reduced two measures of exploratory activity in aged rats but increased speed of performance in a radial maze; the drug also caused substantially improved retention of spatial information. These results are similar to those obtained with BDP-12, an analog that differs from BDP-20 in its effects on ligand binding to the AMPA receptor and on the physiological responses of the receptors to glutamate. BDP-20 was approximately ten-fold more potent in behavioral effects than BDP-12, which agrees with the relative potencies of the two drugs as assessed with excised patches and excitatory synaptic responses. These findings indicate that ampakines, though differing in their effects on AMPA-receptor-mediated responses, have similar effects at the behavioral level.

Evidence that a positive modulator of AMPA-type glutamate receptors improves delayed recall in aged humans

Elderly subjects (65-76 years) were tested for recall of nonsense syllables prior to and after oral administration of 1-(quinoxalin-6 ylcarbonyl)piperidine (CX516), a centrally active drug that enhances currents mediated by AMPA-type glutamate receptors. A significant and positive drug effect was found for delayed (5 min) recall at 75 min posttreatment; average scores for the highest dose group were more than twofold greater than for the placebo group. The drug had no evident influence on heart rate or self-assessment of several psychological variables.

Chromium oligopeptide activates insulin receptor tyrosine kinase activity

A possible new mechanism for the amplification of insulin receptor tyrosine kinase activity in response to insulin has been identified. The chromium-containing oligopeptide low molecular weight chromium-binding substance (LMWCr) does not effect the tyrosine protein kinase activity of rat adipocytic membrane fragments in the absence of insulin; however, insulin-stimulated kinase activity in the membrane fragments is increased up to 8-fold by the oligopeptide. Using isolated rat insulin receptor, LMWCr has been shown to bind to insulin-activated insulin receptor with a dissociation constant of circa 250 pM, resulting in the increase of its tyrosine protein kinase activity. The ability of LMWCr to stimulate insulin receptor tyrosine kinase activity is dependent on its chromium content. The results appear to explain the previously poorly understood relationship between chromium and adult-onset diabetes and cardiovascular disease.

Evaluation of structure-function relationships in the core light-harvesting complex of photosynthetic bacteria by reconstitution with mutant polypeptides

Seven mutant LH1 polypeptides of Rhodobactor sphaeroides have been isolated, and their behaviors in in vitro reconstitution of LH1 and its subunit complex have been characterized. Two mutants were selected to address the increased stability of the subunit complex of Rb. sphaeroides compared with that of Rhodobacter capsulatus. We found that this difference can be largely ascribed to the existence of Tyr at position +4 in the beta-polypeptide (the numbering system used assigns position 0 to the His which provides the coordinating ligand to bacteriochlorophyll) of the former bacterium compared to Met in that position in the latter. The amount of energy involved in the increased interaction was 1.6 kcal/mol, which would be consistent with a hydrogen bond involving Tyr. Mutation of the His at position 0 to Asn allows an estimate of the binding energy for subunit formation contributed by coordination of the imidazole group of His to the Mg atom of bacteriochlorophyll of >4.5 kcal/mol per BChl. Finally, an evaluation of the role of amino acids in the C-terminal region of the alpha-polypeptide was begun. Reconstitution of a mutant alpha-polypeptide in which Trp at position +11 was changed to Phe resulted in optimal formation of an LH1-type complex whose lambda(max) was blue-shifted to 853 nm, the same as observed in the intact bacterium harboring this mutation. These results provide further confirmation that the environment of BChl in reconstituted LH1 complexes is the same as in vivo and support the assignment of this residue to a role in hydrogen bonding with the C3(1) carbonyl group of BChl. Two other mutants of the alpha-polypeptide in which 5 and 14 amino acids in the C-terminus were deleted were also examined. These were of interest because the latter mutant, unlike the former, resulted in a low level of expression of LH1 in intact cells. However, with both of these mutant polypeptides, reconstitution appeared identical to that of the native system. In the case of the mutant shortened by 14 amino acids, a small blue-shift in lambda(max) to 861 nm was observed, again reproducing the blue-shift exhibited by the intact cells. Thus, these results suggest that the lowered levels of in vivo expression observed in these two mutants are due to reduced incorporation of the alpha-polypeptide into the membrane or its increased degradation, rather than to decreased stabilization of the LH1 complex.

Isolation and characterization of a biologically active chromium oligopeptide from bovine liver

Low-molecular-weight chromium-binding substance (LMWCr), the only known naturally occurring Cr-containing polypeptide from mammals and candidate for the biologically active form of chromium, has been isolated for the first time in yields sufficient for spectroscopic studies capable of providing structural and mechanistic data on a molecular level. The results of paramagnetic 1H NMR, electron paramagnetic resonance, and electronic spectroscopic studies indicate that the four chromic ions per polypeptide are probably arranged in an integer-spin tetranuclear assembly, although an alternate possibility, the presence of two dinuclear assemblies, could not be ruled out. This assembly (or assemblies) is bridged by anionic ligands and supported by carboxylates provided by the polypeptide.

Normalization of the peripheral blood T cell receptor V beta repertoire after cultured postnatal human thymic transplantation in DiGeorge syndrome

Complete DiGeorge syndrome is an immunodeficiency disease characterized by thymic aplasia and the absence of functioning peripheral T cells. A patient with this syndrome was transplanted with cultured postnatal human thymic tissue. Within 5 weeks of transplantation, flow cytometry, T cell receptor V beta sequence analysis, and cell function studies showed the presence of oligoclonal populations of nonfunctional clonally expanded peripheral T cells that were derived from pretransplantation T cells present in the skin. However, at 3 months posttransplantation, a biopsy of the transplanted thymus showed normal intrathymic T cell maturation of host T cells with normal TCR V beta expression on thymocytes. By 9 months postransplantation, peripheral T cell function was restored and the TCR V beta repertoire became polyclonal, coincident with the appearance of normal T cell function. These data suggest that the transplanted thymus was responsible for the establishment of a new T cell repertoire via thymopoiesis in the chimeric thymic graft.

Cognitive correlates of long-term cannabis use in Costa Rican men

BACKGROUND

Cognitive correlates of long-term cannabis use have been elusive. We tested the hypothesis that long-term cannabis use is associated with deficits in short term memory, working memory, and attention in a literate, westernized culture (Costa Rica) in which the effects of cannabis use can be isolated.

METHODS

Two cohorts of long-term cannabis users and nonusers were studied. Within each cohort, users and nonusers were comparable in age and socioeconomic status. Polydrug users and users who tested positive for the use of cannabis at the time of cognitive assessment after a 72-hour abstention period were excluded. The older cohort (whose age was approximately 45 years) had consumed cannabis for an average of 34 years, and comprised 17 users and 30 nonusers, who had been recruited in San José, Costa Rica, and had been observed since 1973. The younger cohort (whose age was approximately 28 years) had consumed cannabis for an average of 8 years, and comprised 37 users and 49 nonusers. Short-term memory, working memory, and attentional skills were measured in each subject.

RESULTS

Older long-term users performed worse than older nonusers on 2 short-term memory tests involving learning lists of words. In addition, older long-term users performed worse than older nonusers on selective and divided attention tasks associated with working memory. No notable differences were apparent between younger users and nonusers.

CONCLUSION

Long-term cannabis use was associated with disruption of short-term memory, working memory, and attentional skills in older long-term cannabis users.

An ounce of prevention? Evaluation of the 'Put Prevention into Practice' program

BACKGROUND

The "Put Prevention into Practice" (PPIP) program was designed to enhance the capacity of health care providers to deliver clinical preventive services. This study was designed to evaluate the program's effectiveness when applied to family physicians in private practice settings.

METHODS

Eight Midwestern practices that had purchased PPIP kits were identified and agreed to participate in the study. A comparative case study approach encompassing a variety of data collection techniques was used. These techniques included participant observation of clinic operations and patient encounters, semistructured and key informant interviews with physicians and staff members, chart reviews, and structured postpatient encounter and office environment checklists. Content analysis of the qualitative data and construction of the individual cases were done by consensus of the research team.

RESULTS

PPIP materials are not being used, even by the clinics that ordered them. Physicians already providing quality preventive services prefer their existing materials to those in the PPIP kit. Sites that are underutilizing preventive services are unable or unwilling to independently implement the PPIP program.

CONCLUSIONS

Development of technical support may facilitate implementation of PPIP materials into those practices most deficient in providing preventive services. Given the diversity of practice environments it is unlikely that a "one size fits all" approach will ever be able to address the needs of all providers.

A biologically active form of chromium may activate a membrane phosphotyrosine phosphatase (PTP)

Chromium is essential for proper carbohydrate and lipid metabolism in mammals, although the mechanism of this action has previously proved elusive. Low-molecular-weight chromium-binding protein (LMWCr), a biologically active form of chromium in mammals, potentiates the effect of insulin on the conversion of glucose into lipid and into carbon dioxide in isolated adipocytes. Kinetics studies indicate that LMWCr isolated from bovine liver activates phosphotyrosine phosphatase (PTP) activity in adipocyte membranes while having no intrinsic phosphatase activity. This activation is directly proportional to the amount of added LMWCr. The pattern of inhibition of this activity in the presence of a number of known phosphatase inhibitors suggests the involvement of a membrane phosphotyrosine phosphatase similar to PTP1A' or PTP1B. We propose that chromium plays a biological role in the activation of a membrane phosphotyrosine phosphatase.

Strain-dependent susceptibility to radiation-induced mammary cancer is a result of differences in epithelial cell sensitivity to transformation

Variations in sensitivity to radiation-induced mammary cancer among different strains of mice are well known. However, the reasons for these variations have not been determined. In the present study, the cell dissociation assay was used to determine the radiation-induced transformation frequencies in sensitive BALB/c mice and resistant C57BL mice as well as the resistant hybrid B6CF1 independent of host environment. The influence of host environment on the progression of transformed cells to the neoplastic phenotype was also examined. Results demonstrated that the variations in sensitivity among these sensitive and resistant mice are a result of inherent differences in the sensitivity of the mammary epithelial cells to radiation-induced transformation. Under the conditions used, host environment played no role in the initiation of transformed cells by radiation or in the progression of these cells to the neoplastic phenotype.

Tryptophan depletion and aggressive responding in healthy males

In order to study the effect of decreasing plasma tryptophan levels on aggressive responding in a controlled laboratory setting, we administered two doses (25 g and 100 g) of a tryptophan-free amino acid mixture to ten healthy male subjects after 24 h of a low tryptophan diet. Subjects were screened for current or past psychiatric, or non-psychiatric medical illness. Aggressive responding on a free-operant laboratory measure of aggression (the Point Subtraction Aggression Paradigm) and plasma tryptophan levels were measured before and after drinking the amino acid mixture. There was a significant increase in aggressive responding 5 h after the 100 g mixture and a significant increase in aggressive responding 6 h after the 25 g mixture compared to a baseline day when no drink was administered. There was also a significant decrease in plasma tryptophan at 5 hours after ingestion compared to baseline for both doses of amino acid mixture. This study supports the hypothesis that tryptophan depletion increases aggressive responding in healthy males in a laboratory setting, probably by decreasing brain serotonin.

Comparison of the structural requirements for bacteriochlorophyll binding in the core light-harvesting complexes of Rhodospirillum rubrum and Rhodospirillum sphaeroides using reconstitution methodology with bacteriochlorophyll analogs

Bacteriochlorophyll (BChl) structural requirements for formation of the core light-harvesting complex (LH1) and its structural subunit complex were examined by reconstitution with BChl analogs and the alpha- and beta-polypeptides of Rhodospirillum rubrum and Rhodobacter sphaeroides. Comparable results were obtained with most of the BChl analogs and the polypeptides of each bacterium, indicating the conservation of BChl binding sites. These systems showed the following common requirements for formation of the subunit complex and LH1: (1) Mg or a metal of similar size and coordination chemistry (e.g., Zn, Cd, Ni), (2) a bacteriochlorin oxidation state of the macrocyclic ring, (3) a 13(2)-carbomethoxy group, and (4) an intact ring V. Some structural features were not as critically important. For example, the subunit complex and LH1 could be formed with both sets of polypeptides and BChl b, as well as with analogs containing either short (ethanol) or long (phytol) esterifying alcohols. Two derivatives were identified that behave differently with the two sets of polypeptides. The 3-acetyl group is required to form LH1 in both bacteria, although a subunit-type complex was readily formed with [3-vinyl]BChl a and the polypeptides of Rs. rubrum but formed only slightly under special conditions with polypeptides of Rb. sphaeroides. [13(2)-OH]BChl a(p) formed both subunit- and LH1-type complexes with the alpha- and beta-polypeptides of Rb. sphaeroides but not with those of Rs. rubrum. Thus, some subtle differences in the BChl binding sites exist in the LH1 complexes of these two bacteria.

Early family experiences and helping behaviors of physical therapists

BACKGROUND AND PURPOSE

Ineffective or excessive helping behavior may encourage helpee dependence and overextension of helper resources. Early family experiences and perceptions of the helpee's situation both contribute to the expression of helping behavior in health professionals. The purpose of this study was to determine how early family experiences and variations in perceived patient responsibility influence physical therapist helping behavior.

SUBJECTS AND METHODS

Five hundred physical therapists were surveyed by mail, resulting in a final sample of 221 (44%) respondents who completed the Family of Origin Scale (FOS), measuring the nature of their early family experiences, and a Helping Questionnaire, measuring their helping behavior, perceptions of replaceability, and feelings of compassion for four hypothetical patients. The four patients represented Brickman's models of helping and coping, varying in high and low responsibility for the problem and high and low responsibility for the solution to the problem.

RESULTS

Subjects who scored in the dysfunctional or neutral ranges on the FOS had lower scores on their willingness to help and feelings of compassion than did subjects who scored in the functional range on the FOS. Regardless of early family experiences, subjects' scores were higher for willingness to help and feelings of compassion and lower in their perceptions of replaceability for patients who were not thought to be responsible for their medical problem (medical and compensatory models). In contrast, subjects' scores were lower for their willingness to help and feelings of compassion and higher in their perceptions of replaceability when patients were felt to be responsible for their medical problem (enlightenment and moral models).

CONCLUSION AND DISCUSSION

All subjects, regardless of early family experience, showed helping responses that linked feelings of compassion with greater tendencies to help. Variations in perceived patient responsibility for the medical problem, rather than early family experience, appears to be a major determinant in motivating both compassion and helping behavior. Thus, helpers may be more likely to overextend themselves or create patient dependence when patients are perceived to be not responsible for the cause of their problem. [Curtis KA, Davis CM, Trimble TK, Papoulidis DK. Early family experiences and helping behaviors of physical therapists.

Latent expression of p53 mutations and radiation-induced mammary cancer

EF42 is a clonally derived preneoplastic cell lineage from irradiated mouse mammary tissue, which becomes neoplastic with time in vitro or in vivo. We now report that multiple mutations in p53 occur before the acquisition of the neoplastic phenotype. The selective expansion of mutant cells is accompanied by loss of heterozygosity at the p53 locus and c-myc amplification. Although p53 mutations represent critical early events, our data argue these mutations were not directly induced by radiation but arose in the progeny of irradiated cells several cell generations later. The data are consistent with a multistep model of carcinogenesis that identifies genomic instability as the earliest step.

Reconstitution of the bacterial core light-harvesting complexes of Rhodobacter sphaeroides and Rhodospirillum rubrum with isolated alpha- and beta-polypeptides, bacteriochlorophyll alpha, and carotenoid

Methodology has been developed to reconstitute carotenoids and bacteriochlorophyll alpha with isolated light-harvesting complex I (LHI) polypeptides of both Rhodobacter sphaeroides and Rhodospirillum rubrum. Reconstitution techniques first developed in this laboratory using the LHI polypeptides of R. rubrum, R. sphaeroides, and Rhodobacter capsulatus reproduced bacteriochlorophyll alpha spectral properties characteristic of LHI complexes lacking carotenoids. In this study, carotenoids are supplied either as organic-solvent extracts of chromatophores or as thin-layer chromatography or high performance liquid chromatography-purified species. The resulting LHI complexes exhibit carotenoid and bacteriochlorophyll a spectral properties characteristic of native LHI complexes of carotenoid-containing bacteria. Absorption and circular dichroism spectra support the attainment of a native-like carotenoid environment in the reconstituted LHI complexes. For both R. sphaeroides- and R. rubrum-reconstituted systems, fluorescence excitation spectra reveal appropriate carotenoid to bacteriochlorophyll alpha energy-transfer efficiencies based on comparisons with the in vivo systems. In the case of R. rubrum reconstitutions, carotenoids afford protection from photodynamic degradation. Thus, carotenoids reconstituted into LHI exhibit spectral and functional characteristics associated with native pigments. Heterologous reconstitutions demonstrate the applicability of the developed assay in dissecting the molecular environment of carotenoids in light-harvesting complexes.

Intra- and interethnic variability in reduced haloperidol to haloperidol ratios

Steady-state haloperidol and reduced haloperidol concentrations were measured in 250 schizophrenic patients from 4 ethnic groups: 39 Blacks, 66 Caucasians, 82 Chinese, and 63 Mexican Americans. The distribution of the reduced haloperidol to haloperidol concentration (RH/HL) ratios was bimodal in all ethnic groups, with the antimode determined by probit plot as 0.46, 0.51, 0.36, and 0.76, respectively. With these antimodes, the proportion of patients with low RH/HL ratios were 41%, 42%, 73%, and 57% in the four ethnic groups, respectively. Compared with the other three ethnic groups, in the Chinese patients the ratio was lower. The mean RH/HL ratio in the Chinese was 0.34 compared with 0.81 to 0.87 in the non-Chinese groups. In 53 patients who were treated with two or more haloperidol dosage regimens, steady-state haloperidol and reduced haloperidol drug concentrations obtained from the different regimens were positively correlated with the haloperidol dose (R = .79 and R = .62, respectively). Our data suggest not only the existence of a bimodal distribution in the RH/HL ratio, but also that the antimode separating the low and high ratio subgroups is different among the various ethnic groups.

A truncated recombinant intercellular adhesion molecule-1 inhibits adhesion of leukemic cell lines to upregulated endothelial cells

Intercellular adhesion molecule-1, a member of the immunoglobulin supergene family, is the ligand for the integrin lymphocyte function associated antigen-1. Intercellular adhesion molecule-1 and lymphocyte function associated antigen-1 binding interactions mediate leukocyte adherence and migration. Previous work has shown that the adherence of lymphocyte function associated antigen-1 is directed to the first immunoglobulinlike domain of the endothelial cell surface protein intracellular adhesion molecule-1. We have constructed a truncated intercellular adhesion molecule-1 gene encoding the first 185 amino acids from the amino terminus and overexpressed it in Escherichia coli. The recombinant protein was purified from insoluble inclusion bodies and refolded into an active conformation by a denaturation/renaturation cycle. The identity of the protein was confirmed by microsequencing and by Western blot analysis using a polyclonal antibody to ICAM-1. We have demonstrated that this soluble region of the otherwise membrane-bound ligand is an inhibitor of Molt or HL-60 cell adhesion to cytokine-stimulated endothelial cells.

Probing protein structural requirements for formation of the core light-harvesting complex of photosynthetic bacteria using hybrid reconstitution methodology

The α- and β-polypeptides of LH1 isolated from four different photosynthetic bacteria (Rhodospirillum rubrum, Rhodobacter sphaeroides, Rhodobacter capsulatus and Rhodopseudomonas viridis) were used for homologous and hybrid reconstitution experiments with bacteriochlorophyll a. Formation of B820-type subunit complexes and LH1-type complexes were evaluated. The β-polypeptides of R. rubrum, Rb. sphaeroides and Rb. capsulatus behaved similarly and formed B820-type subunit complexes in the absence of an α-polypeptide. The α- and β-polypeptides were both required to form a LH1-type complex with each of these three homologous systems. In hybrid experiments where the β-polypeptides were tested for reconstitution with α-polypeptides other than their homologous partners, half of the twelve possible combinations resulted in formation of both B820- and LH1-type complexes. Three of the combinations that did not result in formation of a LH1-type complex involved the β-polypeptide of R. rubrum. It is suggested that these latter results can be explained by charge repulsion between the Lys at position-17 (assigning the conserved His located nearest to the C-terminus as position 0) in the β-polypeptide of R. rubrum and each of the heterologous α-polypeptides tested, all of which have an Arg at this location. Conclusions that can be derived from these experimental results include: (1) the experimental data support the idea that a central core region of approximately 40 amino acids exists in each of the polypeptides, which contains sufficient information to allow formation of both the B820- and LH1-type complexes and (2) a specific portion of the N-terminal hydrophilic region of each polypeptide was found in which ion pairs between oppositely charged groups on the α- and β-polypeptides seem to stabilize complex formation.

Acquired immunodeficiency syndrome-like illness associated with systemic Mycoplasma fermentans infection in a human immunodeficiency virus-negative homosexual man

A 35-year-old homosexual man developed a composite nodal Kaposi's sarcoma and peripheral T-cell lymphoma that were associated with a peripheral blood CD4-positive lymphocyte count of only 43/mm3. The patient subsequently developed Pneumocystis carinii pneumonitis and eventually died due to disseminated Cryptococcus neoformans. Numerous premortem tests for the presence of human immunodeficiency virus (HIV) types 1 and 2 were negative by the enzyme-linked immunosorbent assay, Western blot, viral isolation, and polymerase chain reaction techniques. Postmortem evaluations for HIV-1, HIV-2, human T-cell lymphotropic virus (HTLV)-I, and HTLV-II also were negative by polymerase chain reaction, immunofluorescence assays, and viral isolation. A systemic infection by Mycoplasma fermentans, however, was documented by immunohistochemistry and polymerase chain reaction in premortem and postmortem tissues. This recently recognized human pathogen has produced systemic infections in patients with the acquired immunodeficiency syndrome (AIDS) and in previously healthy non-AIDS patients who characteristically have a fulminant flu-like illness. Additionally, M fermentans has enhanced the cytopathic effect of HIV in in vitro studies and has produced fatal wasting illnesses with terminal lymphopenia in inoculated adult silvered leaf monkeys. This report is the first description of an association between M fermentans infection and an AIDS-like illness in an HIV-negative individual. The etiology of the severe immunosuppression in this patient and the associated role of M fermentans remain to be determined by further investigations.

Characterization of laminin receptor messenger ribonucleic acid and protein expression in mouse spermatogenic cells

A cDNA proposed to encode the mouse laminin receptor (MLR) was isolated from a mouse round spermatid expression library. The cDNA contained complete coding and 3' untranslated regions but was missing the first 42 bases from the 5' untranslated region. Northern blot analysis using a 3' EcoRI fragment of the cDNA identified a 1.2-kb transcript in mouse testes and all somatic tissues tested. Additional transcripts of 1.3 and 0.9 kb were present in round spermatids isolated from mouse testes. Northern blots using ribonuclease (RNase) H-treated poly(A)+ RNA indicated that the difference in the size of 1.3-kb round spermatid transcripts and 1.2-kb transcripts was due to differing poly(A)+ tail lengths. The 0.9-kb round spermatid transcript hybridized to all but the 5' end of the 1.2-kb MLR cDNA, suggesting that an alternate start site is used or that transcript processing occurs in these cells. Immunoblot analysis identified proteins in spermatogenic cells corresponding to the 67-70-kDa MLR and its 43-kDa precursor. In addition, ligand binding studies and affinity chromatography procedures indicated that spermatogenic cell proteins of these sizes bind laminin. However, spermatocytes and spermatids are spatially isolated from laminin in the testes, and MLR may have other functions in these cells.

Cigarette smoking cessation and alcohol treatment

Cigarette smoking is common among problem drinkers and recovering alcoholics but most cessation research has not addressed this special population of smokers. Confidential survey data were collected from over 700 alcoholism counselors and medical personnel in residential and outpatient chemical dependency units (CDUs) in Nebraska to identify the quit smoking method these experts recommend and to assess their personal experiences with smoking cessation. A total of 334 respondents (45% of the group) self-identified as a recovering alcoholic, 51 (7%) as a problem drinker, and 350 (48%) as having no history of alcohol problems. Over 63% of all respondents were former or current smokers. The most frequently recommended quitting methods for people still in treatment for alcohol problems were relying on a support group (69%), adhering to Alcoholics Anonymous (AA) principles (64%), and quitting "cold turkey" (45%). In an adjusted logistic regression model, quitting "cold turkey" and relying on the principles of AA significantly increased a respondent's odds of personally becoming a successful tobacco quitter. We conclude that many recovering alcoholics and problem drinkers can successfully quit smoking and should be encouraged to use abstinence coping skills learned in alcohol treatment.

Recovering staff and smoking in chemical dependency programs in rural Nebraska

The problem of cigarette smoking among those who are recovering from alcohol dependence is becoming more apparent as chemical dependency units (CDUs) are beginning to restrict smoking for clients and staff and more actively encourage nicotine abstinence. To date, little is known about effective smoking cessation techniques for people with a history of alcohol problems. To obtain new data, a survey of personal experiences with smoking cessation and professional recommendations about nicotine dependence was administered to 124 recovering treatment professionals in CDUs in rural Nebraska. Among the 99 staff with a history of smoking, 81 (80%) had tried to quit smoking and 38 were former smokers at the time of the survey. Quitting "cold turkey" was the most popular smoking cessation method. Reliance on AA principles was second. The results suggest that recovering staff can successfully quit smoking by applying their professional practice guidelines for alcohol treatment to their personal problems with tobacco.

Identification of a role of the vitronectin receptor and protein kinase C in the induction of endothelial cell vascular formation

When cultured on a basement membrane substratum, endothelial cells undergo a rapid series of morphological and functional changes which result in the formation of histotypic tube-like structures, a process which mimics in vivo angiogenesis. Since this process is probably dependent on several cell adhesion and cell signaling phenomena, we examined the roles of integrins and protein kinase C in endothelial cell cord formation. Polyclonal antisera directed against the entire vitronectin (alpha v beta 3) and fibronectin (alpha 5 beta 1) receptors inhibited cord formation. Subunit-specific monoclonal antibodies to alpha v, beta 3, and beta 1 integrin subunits inhibited cord formation, while monoclonal antibodies to alpha 5 did not, which implicated the vitronectin receptor, and not the fibronectin receptor, in vascular formation. Protein kinase C inhibitors inhibited cord formation, while phorbol 12-myristate 13-acetate (PMA) caused endothelial cells to form longer cords. Since the vitronectin receptor has been shown to be phosphorylated in an in vitro system by protein kinase C, the possible functional link between the vitronectin receptor and protein kinase C during cellular morphogenesis was examined. The vitronectin receptor was more highly phosphorylated in cord-forming endothelial cells on basement membrane than in monolayer cells on vitronectin. Furthermore, this phosphorylation was inhibited by protein kinase C inhibitors, and PMA was required to induce vitronectin receptor phosphorylation in endothelial cells cultured on vitronectin. Colocalization studies were also performed using antisera to the vitronectin receptor and antibodies to protein kinase C. Although no strict colocalization was found, protein kinase C was localized in the cytoskeleton of endothelial cells initially plated on basement membrane or on vitronectin, and it translocated to the plasma membrane of C-shaped cord-forming cells on basement membrane. Thus, both the vitronectin receptor and protein kinase C play a role in in vitro cord formation.

Microbial etiology of acute pneumonia in hospitalized patients

The purpose of this study was to determine the microbial etiology of pneumonia by using strict criteria among a group of hospitalized patients. Patients with acute community-acquired or hospital-acquired pneumonia were studied in a systematic and comprehensive manner for bacterial, viral, chlamydial, mycobacterial, and fungal pathogens. A total of 198 patients with 204 episodes of pneumonia were evaluated. Despite 100 percent follow-up of all surviving patients, a specific etiologic agent could be found in only 103 episodes. Among 154 episodes of community-acquired pneumonia, a diagnosis was made in 79; the most common pathogen was from the genus Legionella, followed by various Gram-negative enteric bacteria, Gram-positive cocci, influenza A virus, and Mycoplasma pneumoniae. The etiologic agent was found in 24 of the 50 patients with hospital-acquired pneumonia; no pathogen predominated. We conclude that even when elaborate diagnostic studies are done, including many invasive procedures, the etiology can be determined in only about half of the patients with acute pneumonia. The pathogens of pneumonia in this study are not markedly different between community-acquired and hospital-acquired infection.

Comparison of haloperidol and reduced haloperidol plasma levels in four different ethnic populations

1. Plasma haloperidol and reduced haloperidol concentration were measured in four ethnic populations. 2. Plasma samples were obtained under steady-state conditions and obtained 10-12 hours post bedtime dose and prior to the morning dose. 3. Haloperidol and reduced haloperidol plasma levels were assayed by radioimmunoassay and liquid chromatography. 4. A wide interpatient variability between haloperidol dose and plasma concentration was observed for each ethnic group. 5. The Chinese group differed from the other ethnic populations. 6. A nonlinear relationship was observed between haloperidol and reduced haloperidol plasma levels in each ethnic group. Further, the relationship of haloperidol to reduced haloperidol plasma levels differed for each ethnic group. These results suggest that various ethnic groups could metabolize haloperidol and reduced haloperidol differently.

Thiothixene pharmacokinetic interactions: a study of hepatic enzyme inducers, clearance inhibitors, and demographic variables

Fifty-nine plasma thiothixene concentrations were measured in 42 patients as part of routine therapeutic drug monitoring. Data collection included concomitant medications, smoking history, and demographic variables. A retrospective analysis was performed to assess the effect of these parameters on oral thiothixene clearance. When groups of patients were categorized by concomitant medications (i.e., no interacting drugs, enzyme/clearance inducers, and enzyme/clearance inhibitors), thiothixene clearance was found to be significantly increased by enzyme inducing drugs (e.g., anticonvulsants) and decreased by clearance inhibiting agents (e.g., cimetidine). Tobacco smoking significantly increased the hepatic clearance of thiothixene within the no interactions and inhibitor groups, but not in the inducer group. Significantly more patients in the inducer group had nondetectable plasma concentrations of thiothixene than the other groups. When the entire patient population was dichotomized by age, patients less than 50 years old had a significantly greater mean clearance (48.2 +/- 37.8 liters/min) versus those greater than or equal to 50 (20.0 +/- 12.6 liters/min). Men in this cohort exhibited a significantly higher clearance (49.2 +/- 38.7 liters/min) than did the women (22.0 +/- 13.5 liters/min). By taking into account these potential sources of pharmacokinetic variability when monitoring plasma thiothixene concentrations, more appropriate dosing of thiothixene may be achieved. Controlled, prospective studies are needed to validate these findings.

The use of selegiline in Alzheimer's patients with behavior problems

BACKGROUND

Currently there is no regimen for managing the inappropriate behavior seen in Alzheimer's disease that does not cause significant patient sedation. Preliminary evidence suggests selegiline may be effective in behavioral modification without the adverse effects observed with other regimens. The purpose of this study was to document the efficacy of selegiline in Alzheimer's patients with behavior problems.

METHOD

Eight Alzheimer's patients (6 women and 2 men) ranging in age from 50 to 82 years (mean +/- SD = 74.0 +/- 10.5) were enrolled in this single-blind study. Patients received selegiline 10 mg each day for 8 weeks. Prior to drug administration and at the end of Weeks 1, 2, 4, 6, and 8, patients were evaluated for behavior (BEHAVEAD), cognitive function (Mini-Mental State Examination), and caregiver stress (Caregiver Burden Scale).

RESULTS

Of eight enrolled patients, five were available for analysis. No statistically significant differences were found between mean baseline and mean 8-week scores for any of the three tests. However, clinical significance was noted by improvement in cognition (orientation and recall), caregiver stress, and behavior. Behavior was noted to improve in the areas of paranoid and delusional ideation, hallucinations, activity disturbances, anxiety, and phobias.

CONCLUSION

These data suggest that some Alzheimer's patients with behavior problems may benefit from selegiline therapy.

Identification and partial characterization of laminin binding proteins in immature rat Sertoli cells

Laminin, a major component of basement membrane extracellular matrices, promotes differentiation in a number of cell types, including Sertoli cells. We have identified and characterized Sertoli cells. We have identified and characterized Sertoli cell surface molecules which interact with laminin. Using laminin-Sepharose affinity chromatography and [125I]laminin binding to Sertoli cell plasma membranes, binding proteins have been identified with the Mr 110,000, 67,000, 55,000, 45,000, 36,000, and 25,000. In addition, the Mr 110,000 and 67,000 laminin binding proteins were phosphorylated. The 67,000, 45,000, and 36,000 react with antibodies to the previously characterized laminin receptor and these antibodies stain the basolateral surface of Sertoli cells in vivo. Cultured Sertoli cells stain for laminin receptor both on the cell surface and within the cells. Antiserum to the 32,000 and 67,000 laminin binding proteins partially inhibited spreading of Sertoli cells on a laminin-coated culture dish, suggesting a functional importance of those proteins in Sertoli cell differentiation. The 25,000 and 45,000 laminin binding proteins reacted with integrin antibodies, but no high-molecular-weight forms could be detected. Integrin was localized to the cell surface and intracellularly but antibodies did not block Sertoli cell spreading on laminin. This work represents the first identification and characterization of extracellular matrix binding proteins in an endocrine organ and suggests an important role for the nonintegrin 32/67 laminin binding proteins.

A retinoic acid response element is part of a pleiotropic domain in the phosphoenolpyruvate carboxykinase gene

Several hormones, including insulin, glucagon, and glucocorticoids, regulate the expression of the rate-limiting gluconeogenic enzyme, phosphoenolpyruvate carboxykinase [GTP: oxaloacetate carboxy-lyase (transphosphorylating); EC 4.1.1.32; PEPCK] in liver. In this report we demonstrate that retinoic acid (RA) also regulates PEPCK expression by inducing a 3-fold increase in the rate of transcription of the PEPCK gene. A RA response element located between -468 and -431 in the PEPCK promoter mediates a 7-fold increase in expression of a chimeric construct containing the basal PEPCK promoter ligated to the chloramphenicol acetyltransferase reporter gene. This element confers RA responsiveness through the heterologous thymidine kinase promoter and functions relatively independent of position and orientation. An 18-base-pair core sequence (-451 to -434) (i) mediates an effect of RA on PEPCK gene expression and contains motifs found in two other RA response elements; (ii) corresponds to AF1, an accessory factor element that is an integral component of the complex glucocorticoid response unit in the PEPCK gene promoter; (iii) is in a region involved in the developmental expression of the PEPCK gene; and (iv) shows homology to elements involved in the tissue-specific regulation of genes, including the hepatic apolipoprotein genes and the alpha 1-antitrypsin gene.

Differential expression of extracellular matrix components in rat Sertoli cells

We studied expression of laminin, fibronectin, and Type IV collagen in the testis by means of immunofluorescence and immunoblot analysis and also examined gene expression of fibronectin using the ribonuclease protection assay. By immunofluorescence on sections from 20-day-old rats, laminin, fibronectin, and Type IV collagen were found in the basement membrane of the seminiferous tubules and in the interstitial regions of the testis. No localization of any extracellular matrix components was found inside the sectioned cells. However, when Sertoli cells were cultured on glass coverslips, laminin and Type IV collagen were both found inside the cells, suggesting new synthesis. In cultured peritubular cells, Type IV collagen, laminin, and fibronectin were found within the cells. When examined by immunoblot analysis, freshly isolated Sertoli and peritubular cells from 20-day-old rats did not demonstrate production of laminin or fibronectin. After 5 days in culture, peritubular cells produced both laminin and fibronectin, whereas cultured Sertoli cells produced only laminin. In contrast, freshly isolated and cultured Sertoli and peritubular cells all produced Type IV collagen. Moreover, the ribonuclease protection assay indicated that the bulk of fibronectin gene expression occurs within the first 10 days of postnatal development, with lower maintenance levels occurring thereafter. These results indicate that in the testis the highest levels of expression of laminin and fibronectin occur during development and in primary cell culture, whereas expression of Type IV collagen is higher at later stages.