Feedback on audit and action planning for dental caries control: a qualitative study to investigate the acceptability among interdisciplinary pediatric dental care teams

Introduction

American Indian and Alaska Native children suffer from the poorest oral health of all populational groups in the United States. Evidence-based practices (EBP) for caries control are well established, but systematically implementing such practices have proven difficult. Audit and feedback with goal setting, and action planning to implement these EBPs have not been tested or adapted for Alaska Native healthcare settings. The aim of this study was to investigate acceptability and perceived feasibility of an audit and feedback intervention for pediatric dental caries control among dental providers and patient stakeholders.

Methods

The pilot program was implemented in two dental clinics from a tribal healthcare consortium in Alaska. Key-informant interviews were conducted to investigate the contextual, organizational, and behavioral facilitators and barriers to the implementation and expansion of the program. Interview transcripts were analyzed by two researchers using thematic analysis.

Results

Eight key informants were interviewed twice (during and after the intervention period), and one once, for a total of 17 interviews. Patient stakeholders were not interviewed due to COVID-19 pandemic clinic closures and social isolation mandates. Three principal themes emerged: a positive organizational climate and culture fostered the acceptability of the program, the positive impacts of the program observed in the pediatric dental teams and the organization, and the challenges to implement the program including understanding the data reports, trusting the accuracy of the data, and competing priorities.

Conclusions

The intervention of audit and feedback with goal setting and action planning was well accepted and perceived as feasible by the study participants given the financial and human resources provided by the research project. This qualitative study can inform the design and evaluation of process-oriented implementation strategies geared towards decreasing health inequities and improving health outcomes, such as dental caries in American Indian and Alaska Native children and adolescents.

Feasibility and acceptability of home delivery of water for dental caries control in Latinx children-"Sediento por una Sonrisa," Thirsty for a Smile: Single-arm feasibility study

Background

Outcomes of surgical treatments under general anesthesia for early childhood caries of young children from low-income groups are poor requiring retreatment within 2 years. Dietary sugar is an ideal intervention target given that it is the most prominent risk factor for dental caries and there is increasing evidence of successful interventions to reduce its intake. Our aim is to investigate the feasibility and acceptability of the Thirsty for a Smile intervention, designed to promote consumption of water in lieu of sugar sweetened beverages, among children who underwent surgery for early childhood caries and their caregivers, mostly from Latino heritage.

Methods

A single-arm feasibility study was conducted in a dental practice from a community health center in eastern Washington State. Bottled water was delivered to the participants' homes and caregivers received patient-centered counseling for setting goals to increase children's water intake and reduce sugar sweetened beverages consumption. We assessed the feasibility and acceptability of the intervention and study procedures through participation rates, interviews and a questionnaire completed by the caregivers. Data was analyzed and themes and descriptive statistics presented.

Results

Twenty-two dyads of caregivers and their children between 2 and 9 years old who recently had surgical treatment for early childhood dental caries were enrolled. All study assessments were completed by more than 90% of participants, except for the final 24-h dietary recall (73%). Dietary counseling, both in person and brief telephone calls, was highly acceptable to the caregivers, and they also reported their children enjoyed and used the water bottles. On a scale from 1 to 10, the average rating for the helpfulness of the dietary counseling component for changing child's drinking habits was 9.62 and for the water delivery component, 8.86.

Conclusions

This study tested the feasibility of conducting a trial in a dental practice setting, and the acceptability among caregivers of young children who underwent surgery for early childhood caries. It demonstrated that the Thirsty for a Smile intervention and study processes were feasible and acceptable. The study provides useful information for implementation of a two-arm randomized controlled trial in this setting and may also benefit other researchers attempting to test similar interventions.

Home Delivery of Water for Caries Prevention in Latinx Children (“Sediento por una Sonrisa,” Thirsty for a Smile): Protocol for a Single-Arm Feasibility Study

Background

Dental caries has significant public health implications afflicting young children. In addition to low social economic status, the most prominent risk factor for early childhood caries is sugar in the diet, particularly sugar-sweetened beverages. Dental treatment for caries in young children is commonly performed under general anesthesia and a significant proportion of children require repeated treatment. Interventions to reduce sugar-sweetened beverage consumption could lead to reduced rates of retreatment for dental caries in young children.

Objective

This protocol describes the rationale, design, and methods of the “Thirsty for a Smile” feasibility study. The aim of the study is to assess the feasibility, acceptability, and appropriateness of a dietary intervention promoting water consumption in lieu of sugar-sweetened beverages among young patients, mostly from Latino heritage.

Methods

This protocol describes a single-arm feasibility study. Twenty-one dyads of children and their caregivers will be recruited. Children between 2 and 9 years old who recently had treatment under general anesthesia for early childhood dental caries will be eligible to participate. The intervention has two components: (1) environmental, in which bottled water is delivered to participants’ homes; and (2) behavioral, in which caregivers will receive patient-centered counseling to increase children’s water intake and reduce sugar-sweetened beverages consumption. Dental caries and anthropometric data will be collected at examination during baseline and final visits. The primary outcome is feasibility and secondary outcomes are acceptability and appropriateness of the intervention.

Results

Funding has been obtained from the National Institute of Dental and Craniofacial Research and the University of Washington approved the study. The feasibility study was conducted from March to November 2019.

Conclusions

This feasibility study will test the study processes prior to a two-arm randomized controlled trial to determine feasibility and acceptability of the intervention and study procedures. This study may provide useful information for other researchers attempting to test similar interventions.

International Registered Report Identifier (IRRID)

RR1-10.2196/37200

Piperacillin/tazobactam vs ceftazidime in the treatment of neutropenic fever in patients with acute leukemia or following autologous peripheral blood stem cell transplantation: a prospective randomized trial

Piperacillin/tazobactam was compared with ceftazidime for the empirical treatment of febrile neutropenia in patients with acute leukemia or following autologous peripheral blood stem cell transplantation. Owing to inclusion criteria, it was possible for the same patient to be randomized several times. A total of 219 individual patients were admitted to a prospective randomized clinical study: 24 patients were included twice. Patients (23.5%) remained afebrile. Patients who developed febrile neutropenia were randomized to receive intravenous ceftazidime (n = 74 patients, group I) or piperacillin/tazobactam (n = 87 patients, group II). Response to first-line antibiotic treatment was seen in 55% (group I) and 53% (group II). After the addition of vancomycin, a further 19% (group I) and 24% (group II) of the patients became afebrile. Causes of fever were: microbiologically documented infection in 36 and 34 patients of group I and II; Clostridium difficile in eight and 12 patients of group I and II, and fever of unknown origin in 30 and 41 patients of group I and II. One patient died in each group. Single-agent therapy with piperacillin/tazobactam is as effective as ceftazidime in the treatment of neutropenic fever and is well tolerated. Direct and indirect costs of both treatment regimes are equivalent.

Peripherally inserted central venous catheters for autologous blood progenitor cell transplantation in patients with haematological malignancies

BACKGROUND

In contrast to the high risk of haemorrhage associated with the implantation of a central venous catheter (CVC) via the internal jugular or subclavian access, the use of a peripherally inserted catheter (PICC) offers the advantage of a lower risk of bleeding complications. However, the rate of phlebitis is higher with the PICC and its use has been declining. We have studied the benefits and adverse events of a new type of PICC and a common type.

METHODS

From October 1999 to October 2001, 70 PICCs (Olimpicc, Vygon, Germany, n=40; and LIFECATH-PICC(PUR)5FR Vygon, Germany, n=30) were inserted into 66 patients with haematological malignancies and used for high-dose chemotherapy, total parenteral nutrition and autologous blood stem cell transplantation. While removing the catheter, central and peripheral blood cultures were taken. The catheter tip was investigated by the semi-quantitative roll-out method of Maki.

RESULTS

Sixty-five PICCs were removed after a median of 8.9 days. In five cases a catheter-associated significant colonisation with coagulase-negative staphylococci occurred. In two instances catheter-related bacteraemia was found.

CONCLUSION

In our study this catheter system was inserted in 94% of patients without problems and showed a low incidence of phlebitis (5/65). Because of the high rate of catheter malfunction reported during and after our study, the Olimpicc catheter is no longer available. The PICC system, and the LIFECATH-PICC(PUR)5FR in particular, offers a safe and effective alternative for central venous access to the internal jugular vein.

Use of erythropoietin in patients with multiple myeloma

The prevalence of tumour anaemia in patients with multiple myeloma is greater than 80%. At the time of diagnosis 20% of these patients are already anaemic. In about 70% of patients with multiple myeloma, recombinant human erythropoietin (r-HuEPO) leads to a reduction in transfusion frequency, resulting in a drop in transfusion- related side-effects like infections and immune reactions, iron overload and hyperviscosity which often negatively influence the course of disease. A further reason for the use of erythropoietin is to achieve and maintain high haemoglobin levels (11-12 g/dl), which are of considerable prognostic significance in patients with multiple myeloma. Increasing Hb levels with r-HuEPO also improve the quality of life of patients, thus leading to better therapy compliance. The trade-off between high costs of an erythropoietin treatment and lower indirect costs (infusion material, personal equipment, patient transport costs, etc.) should be evaluated. Nevertheless, an exact definition of patients for whom the use of erythropoietin is beneficial is warranted. The pathogenesis of anaemia and the clinical experiences of erythropoietin in patients with multiple myeloma are discussed.

Continuous infusion of ceftazidime for patients with breast cancer and multiple myeloma receiving high-dose chemotherapy and peripheral blood stem cell transplantation

This prospective study was performed to examine the safety and efficacy of a continuous infusion of ceftazidime in patients who developed febrile neutropenia after high-dose chemotherapy (HDCT) and autologous peripheral blood stem cell transplantation (PBSCT) and to determine if the underlying disease represents a risk factor for infectious complications. From September 1995 to May 2000, 55 patients with breast cancer (BC, group I, 54 females, one male) and 32 patients with multiple myeloma (MM, group II, 10 female, 22 male) were included in this study. The febrile patients received a 2 g intravenous bolus of ceftazidime, followed by a 4 g continuous infusion over 24 h using a portable infusion pump. If the fever persisted for 72 h a glycopeptide antibiotic was added. The median age was 42 years (range 22-59) in group I and 52 years (range 35-63) in group II. Thirty-five BC patients (64%) and 20 MM patients (63%) responded to the monotherapy with ceftazidime. After addition of a glycopeptide antibiotic, an additional 11 BC patients vs 10 MM patients became afebrile. The causes of fever in group I were fever of unknown origin (FUO) in 49 patients, microbiologically documented infection (MDI) in five patients, and clinically documented infection (CDI) in one patient. The causes of fever in group II were FUO in 22 patients, MDI in eight patients and CDI in two patients. Forty-one febrile episodes in BC patients (75%) and 22 episodes in the MM patients (69%) were successfully managed by out-patient treatment, resulting in a saving of an average of 20 days of inpatient care. Significantly more episodes of MDI and CDI occurred in patients with MM (P = 0.05). The results indicate that BC and MM patients with febrile neutropenia after HDCT and PBSCT can be treated as outpatients with close monitoring to ensure safety. This approach represents a better use of health care resources.

Oligomerization of peptides analogous to the cytoplasmic domains of coatomer receptors revealed by mass spectrometry

Members of the p24 family of type I transmembrane proteins are involved in budding of coat protein type I (COPI)-coated vesicles. They serve as coat protein receptors, binding via their cytoplasmic domains to coatomer, a stable cytosolic protein complex that represents the major coat component of these vesicles. Experimental evidence suggest that p23, a member of the p24 family, binds to coatomer in an oligomeric state and that this binding triggers polymerization of the coat protein. Toward an understanding of this process at the molecular level, formation of noncovalent complexes and their relative stabilities were analyzed by Fourier transform ion cyclotron resonance mass spectrometry using nanoelectrospray ionization. Specificity and stability of oligomers formed were established to depend on characteristic peptide sequence motifs and were confirmed by mass spectrometric competition experiments with control peptides. Mutations in the peptide sequence caused decreased interaction and destabilization of the noncovalent complexes. The formation and relative stabilities of dimeric and tetrameric complexes were assessed to be formed by cytoplasmic tails of coatomer receptors. The direct molecular identification provided by mass spectrometry correlates well with biochemical results. Thus, electrospray ionization mass spectrometry proves to be a powerful tool to investigate physiologically relevant peptide complexes.

[Agoraphobia with panic disorder or epilepsy? Differential diagnostic considerations in a case]

This paper describes a patient suffering from agoraphobia with panic disorder and with a history of self-induced epileptic seizures. The anxiety syndrome causing the admission to hospital could be diagnosed as non epileptic. He was treated successfully with a behaviour therapy. We discuss the possible interactions between anxiety disorders and epileptic seizures and some diagnostic demarcations. We conclude that even people with mild forms of epilepsy may develop an anxiety disorder arising from the fear of again getting epileptic seizures. To work out the different syndromes of epileptic seizures and of panic attacks should be part of the therapy.

The secretory pathway from history to the state of the art

Maintenance of the structural and functional organization of a eucaryotic cell requires the correct targeting of proteins and lipids to their destinations. This is achieved by the delivery of newly synthesized material along the secretory pathway on one hand and by the retrieval of membranes on the other hand. Various models have been suggested over the years to explain traffic flow within the secretory pathway. The only two models that are under discussion to date are the "vesicular model" and the "cisternal maturation model". A wealth of information from various experimental approaches, strongly supports the vesicular model as the general mode of intracellular transport. Three major types of protein-coated transport vesicles are characterized in molecular detail, and have been attributed to various steps of the secretory pathway: COPII-coated vesicles allow exit from the endoplasmic reticulum (ER), COPI-coated vesicles carry proteins within the early secretory pathway, i.e. between ER and Golgi apparatus, and clathrin-coated vesicles mediate transport from the trans-Golgi network (TGN). In this review we will give an overview of the route of a protein along the secretory pathway and summarize the progress that was made within the last decades in the characterization of distinct intracellular transport steps. We will discuss the current models for the formation and fusion of vesicular carriers with a major focus on the mechanism underlying budding of a COPI-coated vesicle.

Mechanisms of vesicle formation: insights from the COP system

The major cytosolic and membrane proteins that represent machinery of coat protein (COP)-coated transport vesicles within the secretory pathway are characterized to date. This has allowed investigation of the molecular mechanisms that underlie the formation of these vesicles. In vitro binding studies and reconstitution experiments have provided insights at the molecular level into the biogenesis of COPII- and COPI-coated vesicles.

Receptor-induced polymerization of coatomer

Coatomer, the coat protein complex of COPI vesicles, is involved in the budding of these vesicles, but the underlying mechanism is unknown. Toward a better understanding of this process, the interaction between coatomer and the cytoplasmic domain of a major transmembrane protein of COPI vesicles, p23, was studied. Interaction of coatomer with this peptide domain results in a conformational change and polymerization of the complex in vitro. This changed conformation also is observed in vivo, i.e., on the surface of authentic, isolated COPI vesicles. An average of four peptides was found associated with one coatomer complex after polymerization. Based on these results, we propose a mechanism by which the induced conformational change of coatomer results in its polymerization, and thus drives formation of the bud on the Golgi membrane during biogenesis of a COPI vesicle.

Expression pattern of mammalian cochlea outer hair cell (OHC) mRNA: screening of a rat OHC cDNA library

The aim of this study was to characterize the mRNA content of mammalian cochlear outer hair cells (OHCs) and to search for specific genes possibly involved in their unique properties. Indeed, OHCs, which feature high-frequency electromotility, are responsible for the exquisite sensitivity and frequency selectivity of the cochlea. Damage to these cells, which occurs in various conditions, causes a reduction in the cochlear sensitivity by about 50 dB and the alteration of frequency discrimination. Total RNA was extracted from about 2000 mechanically dissociated OHCs, and a polymerase chain reaction (PCR) amplified cDNA library was constructed. The presence of the alpha-9 acetylcholine receptor subunit, preferentially expressed in OHCs, was found by direct PCR amplification of the library. A systematic sequencing of 218 clones showed 78% known genes, 11% EST-related sequences, and 11% unknown genes. The known-gene group was characterized by two main features: a large proportion (55%) of mitochondrial transcripts and an abundance in calcium-binding proteins, such as calmodulin and calbindin, for which expression has already been demonstrated in OHCs. Another protein, the oncomodulin recently shown to be OHC specific, was also found, and its mRNA expression was confirmed by in situ hybridization. Among the 24 unknown genes, 7 were expressed in a restricted pattern, including one expressed in cochlea and spleen and, to a lesser extent, in lungs.

Fibroblast growth factor receptor expression in outer hair cells of rat cochlea

Fibroblast growth factors (FGFs) are critical for normal development of the organ of Corti, and may also protect hair cells from ototoxic damage. Four different fibroblast growth factors are known, three of which have different splice variants in the extracellular immunoglobin-like (Ig) III FGF-binding domain, giving different patterns of sensitivity to the different FGFs. Analysis of a cDNA library of rat outer hair cells by the polymerase chain reaction, using isoform specific primers, showed expression only of FGF receptor 3, splice variant IIIc. This allows us to predict the pattern of sensitivity to applied FGFs, which may be useful in targeting outer hair cells selectively during an FGF-based strategy for cochlear therapy.

A single binding site for dilysine retrieval motifs and p23 within the gamma subunit of coatomer

Coatomer, the major component of the coat of COPI transport vesicles, binds both to the dilysine motif of resident membrane proteins of the endoplasmic reticulum and to the cytoplasmic domain of p23, a major type I membrane protein of COPI vesicles. Using a photocrosslinking approach, we find that under native conditions a peptide analogous to the cytoplasmic domain of p23 interacts with coatomer exclusively through its gamma subunit and shares its binding site with a KKXX retrieval motif. However, upon dissociation of coatomer, interaction with various subunits, including an alpha-, beta'-, epsilon-COP subcomplex, of the photoreactive peptide is observed. We suggest that, under physiological conditions, interaction of coatomer with both endoplasmic reticulum retrieval motifs and the cytoplasmic domain of p23 is mediated by gamma-COP.

Peroxisome biogenesis: involvement of ARF and coatomer

Peroxisomal membrane protein (Pmp)26p (RnPex11p), a major constituent of induced rat liver peroxisomal membrane, was found to contain a COOH-terminal, cytoplasmically exposed consensus dilysine motif with the potential to bind coatomer. Biochemical as well as immunocytochemical evidence is presented showing that peroxisomes incubated with preparations of bovine brain or rat liver cytosol recruit ADP-ribosylation factor (ARF) and coatomer in a strictly guanosine 5'-O-(3-thiotriphosphate)-dependent manner. Consistent with this observation, ldlF cells expressing a temperature-sensitive mutant version of the epsilon-subunit of coatomer exhibit elongated tubular peroxisomes possibly due to impaired vesiculation at the nonpermissive temperature. Since overexpression of Pex11p in Chinese hamster ovary wild-type cells causes proliferation of peroxisomes, these data suggest that Pex11p plays an important role in peroxisome biogenesis by supporting ARF- and coatomer-dependent vesiculation of the organelles.

Reversible dissociation of coatomer: functional characterization of a beta/delta-coat protein subcomplex

COPI-coated vesicles mediate protein transport within the early secretory pathway. Their coat consists of ADP ribosylation factor (ARF1, a small guanosine nucleotide binding protein), and coatomer, a cytosolic complex composed of seven subunits, alpha- to zeta-coat proteins (COPs). For coat formation that initiates budding of a vesicle, ARF1 is recruited to the Golgi membrane from the cytosol in its GTP-bound form, and subsequently, coatomer can bind to the membrane. To identify a minimal structure of coatomer capable to bind to Golgi membranes in an ARF1-dependent manner, we have established a procedure to dissociate coatomer under conditions that allow reassociation of the subunits to a complete and functional complex. After dissociation, subunits or subcomplexes can be isolated and may be expected to be functional. Herein we describe isolation of a subcomplex of coatomer consisting of beta- and delta-COPs that is able to bind to Golgi membranes in an ARF1- and GTP-dependent manner.

Direct and GTP-dependent interaction of ADP ribosylation factor 1 with coatomer subunit beta

A site-directed photocrosslink approach was used to elucidate components that interact directly with ADP- ribosylation factor (ARF)-GTP during coat assembly. Two ARF mutants were generated that contain a photolabile amino acid at positions distant to each other within the ARF molecule. Here we show that one of the two positions specifically interacts with coatomer subunit beta both on Golgi membranes and in isolated coat protein complex type I (COPI)-coated vesicles. Thus, a direct and GTP-dependent interaction of coatomer via beta-coat protein complex (COP) with ARF is involved in the coating of COPI-coated vesicles. These data implicate a bivalent interaction of the complex with the donor membrane during vesicle formation.

Architecture of coatomer: molecular characterization of delta-COP and protein interactions within the complex

Coatomer is a cytosolic protein complex that forms the coat of COP I-coated transport vesicles. In our attempt to analyze the physical and functional interactions between its seven subunits (coat proteins, [COPs] alpha-zeta), we engaged in a program to clone and characterize the individual coatomer subunits. We have now cloned, sequenced, and overexpressed bovine alpha-COP, the 135-kD subunit of coatomer as well as delta-COP, the 57-kD subunit and have identified a yeast homolog of delta-COP by cDNA sequence comparison and by NH2-terminal peptide sequencing. delta-COP shows homologies to subunits of the clathrin adaptor complexes AP1 and AP2. We show that in Golgi-enriched membrane fractions, the protein is predominantly found in COP I-coated transport vesicles and in the budding regions of the Golgi membranes. A knock-out of the delta-COP gene in yeast is lethal. Immunoprecipitation, as well as analysis exploiting the two-hybrid system in a complete COP screen, showed physical interactions between alpha- and epsilon-COPs and between beta- and delta-COPs. Moreover, the two-hybrid system indicates interactions between gamma- and zeta-COPs as well as between alpha- and beta' COPs. We propose that these interactions reflect in vivo associations of those subunits and thus play a functional role in the assembly of coatomer and/or serve to maintain the molecular architecture of the complex.

Nonclathrin coat protein gamma, a subunit of coatomer, binds to the cytoplasmic dilysine motif of membrane proteins of the early secretory pathway

Coatomer, a cytosolic heterooligomeric protein complex that consists of seven subunits [alpha-, beta-, beta'-, gamma-, delta-, epsilon-, and zeta-COP (nonclathrin coat protein)], has been shown to interact with dilysine motifs typically found in the cytoplasmic domains of various endoplasmic-reticulum-resident membrane proteins [Cosson, P. & Letourneur, F. (1994) Science 263, 1629-1631]. We have used a photo-cross-linking approach to identify the site of coatomer that is involved in binding to the dilysine motifs. An octapeptide corresponding to the C-terminal tail of Wbp1p, a component of the yeast N-oligosaccharyltransferase complex, has been synthesized with a photoreactive phenylalanine at position -5 and was radioactively labeled with [125I]iodine at a tyrosine residue introduced at the N terminus of the peptide. Photolysis of isolated coatomer in the presence of this peptide and immunoprecipitation of coatomer from photo-cross-linked cell lysates reveal that gamma-COP is the predominantly labeled protein. From these results, we conclude that coatomer is able to bind to the cytoplasmic dilysine motifs of membrane proteins of the early secretory pathway via its gamma-COP subunit, whose complete cDNA-derived amino acid sequence is also presented.

COP-coated vesicles in intracellular protein transport

COP-coated vesicles have originally been implicated in vesicular transport between subcompartments of the Golgi complex in mammals in a cis to trans direction. More recently, a role for COP-coated vesicles in transport between the endoplasmic reticulum (ER) and Golgi in mammalian cells has been proposed. Under certain conditions COP-coats have been localized to special domains of the transitional ER and to the cis side of the Golgi complex. This led to the assumption that COP-coated vesicles are involved in export of proteins from the ER. In addition, new findings point to a function of COP-coated vesicles in back transport of proteins from the Golgi to the ER. At present it is not known whether COP-coated vesicles move only in one or in both directions between ER and Golgi.

Non-clathrin-coat protein alpha is a conserved subunit of coatomer and in Saccharomyces cerevisiae is essential for growth

To complete the molecular characterization of coatomer, the preformed cytosolic complex that is involved in the formation of biosynthetic transport vesicles, we have cloned and characterized the gene for non-clathrin-coat protein alpha (alpha-COP) from Saccharomyces cerevisiae. The derived protein, molecular weight of 135,500, contains four WD-40 repeated motifs (Trp/Asp-containing motifs of approximately 40 amino acids). Disruption of the yeast alpha-COP gene is lethal. Comparison of the DNA-derived primary structure with peptides from bovine alpha-COP shows a striking homology. alpha-COP is localized to coated transport vesicles and coated buds of Golgi membranes derived from CHO cells.

Yeast coatomer contains a subunit homologous to mammalian beta'-COP

The homologue of the mammalian coatomer complex was isolated from yeast cytosol and separated on a modified urea-containing SDS-polyacrylamide gel system. An additional band in the 100 kDa molecular weight range appeared when compared to the protein pattern obtained in conventional Laemmli gels, exactly as observed for mammalian coatomer. Cross-reactivity with an anti-peptide antibody raised against the C-terminus of beta'-COP from bovine, and N-terminal sequence analysis, revealed that this protein from yeast is related to beta'-COP from mammals.

beta′-COP, a novel subunit of coatomer

Several lines of evidence favour the hypothesis that intracellular biosynthetic protein transport in eukaryotes is mediated by non-clathrin-coated vesicles (for a review see Rothman and Orci, 1992). The vesicles have been isolated and a set of their surface proteins has been characterized as coat proteins (COPs). These COPs exist in the cytosol as a preformed complex, the coatomer, which was prior to this study known to contain six subunits: four (alpha-, beta-, gamma- and delta-COP) with molecular weights between 160 and 58 kDa, and two additional proteins of approximately 36 and 20 kDa, epsilon- and xi-COP. Here we describe a novel subunit of the coatomer complex, beta'-COP. This subunit occurs in amounts stoichiometric to the established COPs both in the coatomer and in nonclathrin-coated vesicles and shows homology to the beta-subunits of trimeric G proteins.

Transport of the lysosomal membrane glycoprotein lgp120 (lgp-A) to lysosomes does not require appearance on the plasma membrane

We have used stably transfected CHO cell lines to characterize the pathway of intracellular transport of the lgp120 (lgp-A) to lysosomes. Using several surface labeling and internalization assays, our results suggest that lgp120 can reach its final destination with or without prior appearance on the plasma membrane. The extent to which lgp120 was transported via the cell surface was determined by two factors: expression level and the presence of a conserved glycine-tyrosine motif in the cytoplasmic tail. In cells expressing low levels of wild-type lgp120, the majority of newly synthesized molecules reached lysosomes without becoming accessible to antibody or biotinylation reagents added extracellularly at 4 degrees C. With increased expression levels, however, an increased fraction of transfected lgp120, as well as some endogenous lgp-B, appeared on the plasma membrane. The fraction of newly synthesized lgp120 reaching the cell surface was also increased by mutations affecting the cytoplasmic domain tyrosine or glycine residues. A substantial fraction of both mutants reached the surface even at low expression levels. However, only the lgp120G----A7 mutant was rapidly internalized and delivered from the plasma membrane to lysosomes. Taken together, our results show that the majority of newly synthesized wild-type lgp120 does not appear to pass through the cell surface en route to lysosomes. Instead, it is likely that lysosomal targeting involves a saturable intracellular sorting site whose affinity for lgp's is dependent on a glycine-tyrosine motif in the lgp120 cytoplasmic tail.

Basolateral sorting in MDCK cells requires a distinct cytoplasmic domain determinant

In MDCK cells, Golgi to basolateral transport of several membrane proteins has been found to involve a cytoplasmic domain determinant. In some cases (Fc receptor, lysosomal glycoprotein Igp120), the determinant appears similar to that required for endocytosis via clathrin-coated pits; for Igp120, elimination of a single cytoplasmic domain tyrosine both blocks internalization and results in apical transport. In other cases (LDL receptor), the determinant does not involve the cytoplasmic domain tyrosine required for endocytosis. Thus, contrary to current models, basolateral transport in MCDK cells occurs not by default but depends on one or more cytoplasmic domain determinants, the precise nature of which is unknown. For some proteins, it is closely related to coated pit determinants. The fact that many membrane proteins can reach the apical surface in the absence of this determinant suggests that signals for apical transport are widely distributed.

The effect of postpartum lactation counseling on the duration of breast-feeding in low-income women

We investigated the effectiveness of a program of intensive postpartum support for low-income, breast-feeding women and identified potential predictors of prolonged breast-feeding in this population. Ninety-seven low-income women were randomized to receive intensive postpartum education and support for breast-feeding or to receive only the routine assistance provided by the obstetrical nurses. Both groups were telephoned 6 weeks post partum to determine the method of infant feeding then, and those still breast-feeding were contacted monthly until complete weaning had occurred. No significant difference in breast-feeding duration between the two groups was noted. There was no association between duration of nursing and race, marital status, or the need to return to work or school. Earlier age at introduction of supplement, younger maternal age, and participation in prenatal classes predicted breast-feeding duration by logistic regression.

The infant feeding decision in low and upper income women

Few studies have described the woman who chooses breast-feeding by more than simple demographics. The purpose of our study was to characterize new mothers by their infant feeding decisions, by demographic and obstetrical data, and by sources of personal support they received during their pregnancies and in making their infant feeding decisions. To this end, 220 were interviewed, including 116 who chose to breastfeed. Breast-feeding women were more likely to be older, more educated, married, more affluent, experienced with breast-feeding, to have demonstrated good prenatal habits, and to have received support from other sources than those who chose bottle feeding. Participation in Lamaze classes, previous successful breast-feeding, and maternal education were significant predictors of feeding choice, and mode of delivery predicted duration of breastfeeding. Low income women who chose breastfeeding resembled low income bottle feeders in certain medical/social factors, but they showed support patterns similar to middle to upper income women.

Hydrophobic binding of the ectodomain of influenza hemagglutinin to membranes occurs through the "fusion peptide"

Toward elucidating molecular details of virus-induced membrane fusion, we have studied the low pH-triggered interaction of the bromelain-solubilized ectodomain of influenza hemagglutinin with liposomes. Polypeptide segments which insert into the apolar phase of the lipid bilayer were first labeled specifically using either of the two membrane-restricted carbene-generating reagents, 3-(trifluoromethyl)-3-([125I]iodophenyl)diazirine and 1-palmitoyl-2-[11-[4-[3-(trifluoromethyl)diazirinyl]phenyl] undecanoyl]-sn-glycero-3-phosphorylcholine, and were then identified on the basis of cyanogen bromide and 2-(2-nitrophenylsulfenyl)-3-methyl-3'-bromoindolenine-skatole fragment analysis and Edman degradations. Here, we demonstrate that the hydrophobic interaction is mediated solely by the so-called "fusion peptide" which corresponds to the NH2-terminal segment of the BHA2 subunit of nature influenza hemagglutinin. Predominant sites of labeling within that segment were Phe-3, Ile-6, Phe-9, Trp-14, Met-17, and Trp-21. The average 3-4 residue spacing between consecutive labeled amino acid side chains suggests a helical structure of that segment with an amphiphilic character.

Hydrophobic photolabeling identifies BHA2 as the subunit mediating the interaction of bromelain-solubilized influenza virus hemagglutinin with liposomes at low pH

To investigate the molecular basis of the low-pH-mediated interaction of the bromelain-solubilized ectodomain of influenza virus hemagglutinin (BHA) with membranes, we have photolabeled BHA in the presence of liposomes with the two carbene-generating, membrane-directed reagents 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine ([125I]TID) and a new analogue of a phospholipid, 1-palmitoyl-2-[11-[4-[3-(trifluoromethyl)diazirinyl]phenyl][2-3H] undecanoyl]-sn-glycero-3-phosphocholine ([3H]-PTPC/11). With the latter reagent, BHA was labeled in a strictly pH-dependent manner, i.e., at pH 5 only, whereas with [125I]TID, labeling was seen also at pH 7. In all experiments, the label was selectively incorporated into the BHA2 polypeptide, demonstrating that the interaction of BHA with membranes is mediated through this subunit, possibly via its hydrophobic N-terminal segment. Similar experiments with a number of other water-soluble proteins (ovalbumin, carbonic anhydrase, alpha-lactalbumin, trypsin, and soybean trypsin inhibitor) indicate that the ability to interact with liposomes at low pH is not a property specific for BHA but is observed with other, perhaps most, proteins.

Electrostatic and hydrophobic interactions of the intermediate filament protein vimentin and its amino terminus with lipid bilayers

Immunofluorescence and electron microscopical studies on the intracellular distribution of intermediate filaments (IFs) have demonstrated a close proximity of these cytoskeletal structures to cellular membranes. Moreover, nonepithelial IF (protein)s have been shown to exhibit high affinities for lipids, especially for negatively charged and nonpolar lipids. Here, using hydrophobic labeling with the photoactivatable phosphatidylcholine analogue [3H]1-palmitoyl-2-[11-[4-(trifluoromethyldiazirinyl]undecanoyl+ ++]-sn- glycero-3-phosphorylcholine or with 1-azidopyrene at low and physiological ionic strength, it is demonstrated that the IF subunit protein vimentin can interact with the hydrophobic core of lipid bilayers, in addition to strong ionic relationships between both reactants. Whereas the presence of acidic phospholipids in the lipid vesicles was absolutely essential for efficient vimentin labeling, cholesterol played a synergistic role in this reaction. Proteolytic degradation of photolabeled vimentin localized the derivatization exclusively to the non-alpha-helical, highly positively charged N-terminal domain of the filament protein. Furthermore, circular dichroism studies performed on the isolated N terminus of vimentin revealed a significant increase in the alpha-helical content of the polypeptide upon its interaction with vesicles containing negatively charged phospholipids. These results indicate an amphiphilic character of the N terminus and suggest that the cationic arginine residues of the N-terminal domain react with the negatively charged head groups of acidic phospholipids prior or parallel to interaction of the polypeptide with hydrophobic regions of the lipid bilayer.

Induction and enhancement of progressive motility in hamster caput epididymal spermatozoa

Progressive motility was induced in hamster caput epididymal spermatozoa incubated in Tyrodes medium containing 50 mM theophylline, 1.0% Fraction V bovine serum albumin, and 15% (v/v) heat-treated human seminal plasma. Under these induction conditions, however, the maximum percent of caput spermatozoa exhibiting progressive motility (21%) and the time during which motility was sustained (120 min) were significantly less (p less than 0.05) than that of controls from the cauda epididymidis. Moreover, in contrast to caudal spermatozoa, the majority of the induced caput spermatozoa exhibited some degree of flagellar bending at the neck or midpiece. In subsequent experiments the procedure for motility induction was modified to achieve levels of motility in caput spermatozoa equivalent to those observed for caudal spermatozoa. The addition of 5 microM diamide, a sulfhydryl oxidant, to the induction medium prevented the flagellar angularity observed in induced caput sperm preparations. The percentage of caput spermatozoa induced to progressive motility was increased to levels characteristic of caudal spermatozoa (48%) by the addition of hamster caudal epididymal fluid (CEF) to the induction medium. Finally, the viability of the induced caput spermatozoa was significantly enhanced (p less than 0.05) by the removal of Fraction V albumin from the induction medium. In the presence of CEF and in the absence of albumin, 50% of the caput spermatozoa acquired progressive motility and sustained this motility for 4 h. Moreover, when fatty acid-free, charcoal-extracted albumin instead of Fraction V albumin was utilized in the induction procedure, a maximum of 43% of the caput spermatozoa acquired progressive motility and maintained this motility for 4 h, suggesting that the decreased sperm viability observed in the presence of Fraction V albumin was due to a contaminant of albumin, possibly fatty acids. The studies described herein demonstrate for the first time that immature quiescent caput epididymal spermatozoa can be induced to acquire progressive and sustained motility equivalent to that observed in mature caudal epididymal spermatozoa.

Fetal syphilis in the first trimester

Evidenc of first-trimester fetal syphilis was sought in the products of conception in a therapeutic abortion clinic. During two collection periods of one week, five patients with serologic and clinical data consistent with recent syphilitic infection were identified. Their conceptuses were carefully examined by silver and immunofluorescent stains for the presence of Treponema pallidum. Two of these five conceptuses (9 and 10 weeks' gestation) were found to contain T. pallidum by these methods. The literature supporting the Langhans layer/five months' placental barrier theory is reviewed and discussed in view of these two first-trimester cases.