Patient experiences with blood pressure measurement methods for hypertension diagnosis: Qualitative findings from the BP-CHECK study.

BACKGROUND: Out-of-office blood pressure (BP) measurement is recommended when making a new hypertension diagnosis. In practice, however, hypertension is primarily diagnosed using clinic BP. The study objective was to understand patient attitudes about accuracy and patient-centeredness regarding hypertension diagnostic methods. METHODS: Qualitative study within a randomized controlled diagnostic study conducted between May 2017 and March 2019 comparing the accuracy and acceptability of BP measurement methods among patients in an integrated healthcare delivery system. All participants completed 24-hour ambulatory blood pressure monitoring (ABPM), plus either clinic BP, home BP monitoring (HBPM), or kiosk BP diagnostic testing. Qualitative interviewees (aged 31-76 years, n=35) were recruited from the main study. RESULTS: Participants who completed HBPM found it to be comfortable and low burden, and believed it produced accurate results. Participants in the clinic arm described clinic measurements as inconvenient. Participants in the kiosk arm overall did not favor kiosks due to concerns about accuracy and privacy. Participants described ABPM as the most accurate method due to repeated measurements over the 24-hour period in real-world contexts, but many found it uncomfortable and disruptive. Participants also noted methods that involved repeated measures such as HBPM and ABPM particularly influenced their understanding of whether or not they had hypertension. CONCLUSIONS: Hypertension diagnostic methods that include more BP measurements help patients gain a deeper understanding of BP variability and the lower reliability of infrequent measurements in clinic. These findings warrant implementing strategies to enhance out-office BP diagnostic testing in primary care.

Is Hypertension Diagnostic Testing and Diagnosis Associated With Psychological Distress?

BACKGROUND: Psychological impacts of hypertension diagnostic testing and new hypertension diagnoses are unclear. METHODS: BP-CHECK was a randomized diagnostic study conducted in 2017-2019 in an integrated healthcare system. Participants with no hypertension diagnosis or medications and elevated blood pressure (BP) were randomized to one of three diagnostic regimens: (i) Clinic, (ii) Home, or (iii) Kiosk. Participants completed questionnaires at baseline, after completion of the diagnostic regimens, and at 6 months. Outcomes included changes from baseline in health-related quality of life (HRQOL), BP-related worry, and thoughts about having a stroke or heart attack. RESULTS: Participants (n = 482) were mostly over age 50 (77.0%), and White race (80.3%). HRQOL did not significantly change from baseline to 3 weeks or 6 months. Among all participants, BP-related worry and concerns about having a heart attack or stroke increased significantly from baseline to 3 weeks, with heart attack and stroke concerns significantly higher in the Kiosk compared Clinic and Home groups. At 6 months, thoughts about having a heart attack or stroke returned to baseline overall and in the Kiosk group, however BP-related worry was significantly higher among those with, compared to those without, a new hypertension diagnosis. CONCLUSIONS: The hypertension diagnostic process did not lead to short-term or intermediate-term changes in self-reported HRQOL. However, BP-related worry increased short-term and persisted at 6 months among individuals with a new hypertension diagnosis. Results warrant validation in more representative populations and additional exploration of the impacts of this worry on psychological well-being and hypertension control. CLINICALTRIALS.GOV IDENTIFIER: NCT03130257.

The feasibility, usability, and clinical utility of traditional paper food and symptom journals for patients with irritable bowel syndrome.

BACKGROUND: Paper food and gastrointestinal (GI) symptom journals are used to help irritable bowel syndrome (IBS) patients determine potential trigger foods. The primary aim of this study was to evaluate the feasibility, usability, and clinical utility of such journals as a data collection tool. A secondary aim was to explore a method for analyzing journal data to describe patterns of diet and symptoms. METHODS: Participants (N=17) were asked to log three sets of 3-day food and symptom journals over a 15-day period. Feasibility was evaluated by journal completion rates, symptom logging compliance, and logging fatigability. The feasibility, usability, and clinical utility of journaling were also assessed by a customized evaluation and exit interview. For each journal, regression analyses were conducted to examine relationships between key meal nutrients and subsequent symptoms. KEY RESULTS: Most participants were young (mean age 35±12) Caucasian (N=13) women (N=14). Journal completion rates were 100% for all participants with no logging fatigability. Over half perceived paper journaling of food and symptoms as feasible, usable, and clinically useful. Thirteen participants demonstrated a strong association with at least one symptom and meal nutrient. Patterns of associations differed among participants. CONCLUSIONS AND INFERENCES: Paper journaling of food and GI symptoms for 9 days over a 15-day period appeared to be a feasible and usable data collection tool for IBS patients. Over half perceived journaling as at least somewhat clinically useful. Findings from this study support the anecdote that food trigger(s) and associated symptom(s) vary for each individual.

Longitudinal DRG-based survey of all-cause and pneumococcal pneumonia and meningitis for inpatients in France (2005-2010).

OBJECTIVE: This population-based retrospective study quantified the burden of all-cause and pneumococcal pneumonia and meningitis in the Rhône-Alpes region of France from 2005 to 2010, when the 7-valent pneumococcal conjugate vaccine uptake increased from 50 to>90% in children. PATIENTS AND METHODS: Hospital admission data was obtained from the French Diagnosis Related Groups program database (French acronym PMSI). Patients were residents of the Rhône-Alpes region hospitalized for the diseases of interest during 2005-2010. Hospitalization and in-hospital mortality rates were calculated by age, sex, and year on the basis of the Rhône-Alpes region population. Hospitalization and in-hospital mortality rates were compared using Chi(2) tests with statistical significance adjusted for multiple comparisons. RESULTS: The highest hospitalization rates by age group were: all-cause pneumonia, oldest group (>65 years); all-cause and pneumococcal meningitis, youngest group (0-4 years), and pneumococcal pneumonia, youngest and oldest groups. Hospitalization rates significantly decreased for all-cause pneumonia (5-19 years: -12.71%) and all-cause meningitis (20-49 years: -29.22%). Pneumococcal disease rates did not significantly change in any age group. Mortality rates from all-cause pneumonia and meningitis were highest in the oldest age groups. CONCLUSIONS: The burden of all-cause and pneumococcal pneumonia and meningitis remains substantial. Significant changes (decreases) between 2005 and 2010 in hospitalization rates were limited and varied among age groups, most likely because this study began 2 years after PCV7 was first introduced in France for children at broadly-defined high risk. Further research is needed on the relationship between serotype epidemiology and clinical patterns of disease.

LRRK2 mutations in a clinic-based cohort of Parkinson's disease.

In the last decade, major breakthroughs in the understanding of genetic contributions to Parkinson's disease (PD) have been achieved. Recently, mutations in LRRK2, encoding dardarin, have been found to be responsible for an autosomal dominant parkinsonism (OMIM 607060). We screened 311 subjects (cases: n = 202, controls: n = 109) for the three previously reported LRRK2 mutations. Our investigation revealed a sporadic case of PD with a heterozygous mutation G2019S (c.6055G>A). Here, we present the clinical phenotype of this patient and discuss the implications of genetic testing for the G2019S mutation in patients with sporadic PD.

Dietary supplementation with different vitamin C doses: no effect on oxidative DNA damage in healthy people.

BACKGROUND: Antioxidants are believed to prevent many types of disease. Some previous studies suggest that dietary supplementation with vitamin C results in a decrease in the level of one of the markers of oxidative damage-8-oxoguanine in the DNA of peripheral blood mononuclear cells (PBMC). AIM OF TRIAL: To investigate the effect of different dose levels of dietary supplementation with vitamin C on oxidative DNA damage. METHODS: A randomised double-blind placebo-controlled trial was carried out using three different levels (80, 200 and 400 mg) of dietary vitamin C supplementation in a healthy population of 160 volunteers; supplementation was for a period of 15 weeks followed by a 10 week washout period. Peripheral blood samples were obtained every 5 weeks from baseline to 25 weeks. RESULTS: An increase in PBMC vitamin C levels was not observed following supplementation in healthy volunteers. There was no effect found on 8-oxoguanine measured using HPLC with electrochemical detection for any of the three supplemented groups compared to placebo. 8-oxoadenine levels were below the limit of detection of the HPLC system used here. CONCLUSIONS: Supplementation with vitamin C had little effect on cellular levels in this group of healthy individuals, suggesting their diets were replete in vitamin C. The dose range of vitamin C used did not affect oxidative damage in PBMC DNA.

Skeletal unloading induces resistance to insulin-like growth factor I on bone formation.

Skeletal unloading results in an inhibition of bone formation associated with a decrease in osteoblast number, impaired mineralization of bone, and altered proliferation and differentiation of osteoprogenitor cells. Although such changes are likely to be mediated by multiple factors, resistance to the growth-promoting action of insulin-like growth factor I (IGF-I) has been hypothesized to play an important role. To determine whether skeletal unloading induces resistance to IGF-I on bone formation, we examined the response of unloaded (hindlimb elevation) and normally loaded tibia and femur to IGF-I administration. To eliminate the variable of endogenous growth hormone production and secretion during exogenous IGF-I administration, we used growth hormone-deficient dwarf rats (dw-4). The rats were given IGF-I (2.5 mg/kg/day) or vehicle during 7 and 14 days of unloading or normal loading. This significantly increased the serum level of IGF-I in both the normally loaded and unloaded rats. Unloading did not affect the serum level of IGF-I in the vehicle-treated rats. IGF-I markedly increased periosteal bone formation at the tibiofibular junction of normally loaded rats. Unloading decreased bone formation in the vehicle-treated rats, and blocked the ability of IGF-I to increase bone formation. On the other hand, IGF-I increased periosteal bone formation at the midpoint of the humerus (normally loaded in this model) in both hindlimb-elevated and normally loaded rats. IGF-I significantly increased osteogenic colony number, total ALP activity, and total mineralization in bone marrow osteoprogenitor (BMOp) cells of normally loaded rats. Unloading reduced these parameters in the vehicle-treated rats, and blocked the stimulation by IGF-I. Furthermore, IGF-I administration (10 ng/ml) in vitro significantly increased cell proliferation of the BMOp cells isolated from normally loaded bone, but not that of cells from unloaded bone. These results indicate that skeletal unloading induces resistance to IGF-I on bone formation.

A critical role for lymphotoxin-beta receptor in the development of diabetes in nonobese diabetic mice.

To assess the role of lymphotoxin-beta receptor (LTbetaR) in diabetes pathogenesis, we expressed an LTbetaR-Fc fusion protein in nonobese diabetic (NOD) mice. The fusion protein was expressed in the embryo, reached high levels for the first 2 wk after birth, and then declined progressively with age. High expression of LTbetaR-Fc blocked diabetes development but not insulitis. After the decline in chimeric protein concentration, mice became diabetic with kinetics similar to the controls. Early expression of fusion protein resulted in disrupted splenic architecture. However, primary follicles and follicular dendritic cells, but not marginal zones, developed in aged mice. Hence, LTbetaR signaling is required for diabetes development and regulates follicular and marginal zone structures via qualitatively or quantitatively distinct mechanisms.

A cross-over study of the effect of a single oral feeding of medium chain triglyceride oil vs. canola oil on post-ingestion plasma triglyceride levels in healthy men.

Due to its unique absorption and metabolism characteristics, medium chain triglyceride (MCT) oil, consisting of fatty acids with 8-12 carbons, has been used therapeutically since the 1950s in the treatment of fat malabsorption, cystic fibrosis, epilepsy, weight control, and to increase exercise performance. Medium chain triglycerides are easily hydrolyzed in the intestines and the fatty acids are transported directly to the liver via the portal venous system, in contrast to long-chain fatty acids (LCFAs), which are incorporated into chylomicrons for transport through the lymphatic system or peripheral circulation. Medium chain fatty acids (MCFAs) do not require carnitine to cross the double mitochondrial membrane of the hepatocyte, thus they quickly enter the mitochondria and undergo rapid beta-oxidation, whereas most LCFAs are packaged into triglycerides in the hepatocyte. In this single-blind, randomized, cross-over study, 20 healthy men ingested a single dose of either 71 g of MCT oil or canola oil. Blood samples were taken at baseline and at hours one through five post-ingestion to compare the effect of a single oral dosing of MCT oil versus canola oil on post-ingestion plasma triglyceride levels. Mean triglyceride values after canola oil increased 47 percent above baseline (p <0.001), while mean triglyceride values after MCT oil decreased 15 percent from baseline (p <0.001), which is consistent with several other studies involving short- and longer-term feeding with MCT oil. The effect of long-term usage of MCT oil on triglycerides is yet to be established.

Six putative IQ motifs of the recombinant chicken intestinal brush border myosin I are involved in calmodulin binding.

Chicken brush border myosin I has up to six IQ sequence motifs at which it may bind calmodulin. To determine the relative contributions of these motifs to calmodulin binding, fusion deletion fragments were expressed in Escherichia coli and their ability to bind calmodulin was assessed by the gel overlay technique. The first three N-terminal IQ sites showed strong binding with calmodulin. Surprisingly, the last three incomplete IQ motifs also contributed substantial calmodulin binding. The first and fourth IQ sites bound calmodulin but tended to reduce binding in combination with other sites. The data indicate that interactions among all six IQ motifs contribute to the ability of myosin I to bind calmodulin.

Identification and characterization of staphylococcal enterotoxin types G and I from Staphylococcus aureus.

Staphylococcal enterotoxins are exotoxins produced by Staphylococcus aureus that possess emetic and superantigenic properties. Prior to this research there were six characterized enterotoxins, staphylococcal enterotoxin types A to E and H (referred to as SEA to SEE and SEH). Two new staphylococcal enterotoxin genes have been identified and designated seg and sei (staphylococcal enterotoxin types G and I, respectively). seg and sei consist of 777 and 729 nucleotides, respectively, encoding precursor proteins of 258 (SEG) and 242 (SEI) deduced amino acids. SEG and SEI have typical bacterial signal sequences that are cleaved to form toxins with 233 (SEG) and 218 (SEI, predicted) amino acids, corresponding to mature proteins of 27,043 Da (SEG) and 24,928 Da (SEI). Biological activities for SEG and SEI were determined with recombinant S. aureus strains. SEG and SEI elicited emetic responses in rhesus monkeys upon nasogastric administration and stimulated murine T-cell proliferation with the concomitant production of interleukin 2 (IL-2) and gamma interferon (IFN-gamma), as measured by cytokine enzyme-linked immunoassays. SEG and SEI are related to other enterotoxins of S. aureus and to streptococcal pyrogenic exotoxin A (SpeA) and streptococcal superantigen (SSA) of Streptococcus pyogenes. Phylogenetic analysis and comparisons of amino acid and nucleotide sequence identities were performed on related staphylococcal and streptococcal protein toxins to group SEG and SEI among the characterized toxins. SEG is most similar to SpeA, SEB, SEC, and SSA (38 to 42% amino acid identity), while SEI is most similar to SEA, SEE, and SED (26 to 28% amino acid identity). Polyclonal antiserum was generated against purified histidine-tagged SEG and SEI (HisSEG and HisSEI). Immunoblot analysis of the enterotoxins, toxic-shock syndrome toxin 1, and SpeA with antiserum prepared against HisSEG and HisSEI revealed that SEG shares some epitopes with SEC1 while SEI does not.

Zipper protein, a B-G protein with the ability to regulate actin/myosin 1 interactions in the intestinal brush border.

We recently identified a 28-kDa protein in the intestinal brush border that resembled tropomyosin in terms of size, homology, and alpha helical content. This protein contained 27 heptad repeats, nearly all of which began with leucine, leading to its name zipper protein. Subsequent analysis, however, indicated that both a 49-kDa and a 28-kDa immunoreactive protein existed in intestinal brush-border extracts. Using 5'-rapid amplification of cDNA ends analysis, we extended the N-terminal sequence of zipper protein to the apparent translation start site. This additional sequence contained a putative transmembrane domain and two potential tryptic cleavage sites C-terminal to the transmembrane domain which would release a 28-kDa cytoplasmic protein if utilized. The additional sequence was highly homologous to members of the B-G protein family, a family with no known function. Immunoelectron microscopy showed that zipper protein was confined to the membrane of the microvillus where it was in close association with brush-border myosin 1 (BBM1). Recombinant zipper protein (28-kDa cytoplasmic portion) blocked the binding of actin to BBM1 and inhibited actin-stimulated BBM1 ATPase activity. In contrast, zipper protein had no effect on endogenous or K/EDTA-stimulated BBM1 ATPase activity. Furthermore, zipper protein displaced tropomyosin from binding to actin, suggesting that these homologous proteins bind to the same sites on the actin molecule. We conclude that zipper protein is a transmembrane protein of the B-G family localized to the intestinal epithelial cell microvillus. The extended cytoplasmic tail either in the intact molecule or after tryptic cleavage may participate in regulating the binding and, thus, activation of BBM1 by actin in a manner similar to tropomyosin.

Derivation and partial analysis of two highly active myeloma cell transfectants.

Vectors have been designed to optimise the expression of heterologous proteins in transfected mouse myeloma cells. The over-ridingly important DNA element contained in these constructs is the classical mouse immunoglobulin heavy chain enhancer. It is shown that even in the absence of a well-known promoter element, the enhancer can drive gene expression in stable cell transfectants and the main transcriptional start site utilized in such situations has been mapped to within the previously defined enhancer region. Using chicken lysozyme as a reporter function in these vectors, two transfected myeloma cell clones have been isolated which secrete this protein at levels 50-100-times as high as those usually obtained with the same vectors and it is shown that in molar terms this is at least as high as endogenous immunoglobulin produced by a related line. Analysis of these lines show that in one case only a single copy, and in the other two to three copies, of the apparently unrearranged vector have integrated at a single locus within the genome. Possible explanations for the high-level expression are discussed.

Regulation of calmodulin binding to the ATP extractable 110 kDa protein (myosin I) from chicken duodenal brush border by 1,25-(OH)2D3.

In earlier studies we observed that the active vitamin D metabolite 1,25-(OH)2D3 increased the calmodulin content of purified duodenal brush-border membrane vesicles where it bound principally to the 110 kDa protein myosin I. In this study we further evaluated the regulation of calmodulin binding to ATP releasable myosin I. Whole brush borders (BB) or purified brush-border membrane vesicles (BBMV) were prepared from duodena of vitamin D-deficient rachitic chicks treated 12-18 h before killing with either 625 pmol 1,25-(OH)2D3 or vehicle. The ATP extractable myosin I from BB resulted in an 1.6-fold increase of calmodulin binding to the 110 kDa band after treatment with 1,25-(OH)2D3. In contrast to BB, ATP extraction of myosin I from purified BBMV required alamethicin for ATP entry. As for BB extracts, calmodulin binding to the 110 kDa band in BBMV extracts was also increased about 2.4-fold by 1,25-(OH)2D3. It was concluded that both intact BB and purified BBMV showed the same type of increase in calmodulin binding to ATP releasable myosin I by 1,25-(OH)2D3. To see whether 1,25-(OH)2D3 increased the intrinsic affinity of calmodulin binding to myosin I, the ATP extractable myosin I from BB was purified from rachitic chicks treated with 1,25-(OH)2D3 or vehicle. In contrast to ATP extracts of BB or BBMV, calmodulin binding to the purified myosin I was not different between preparations from 1,25-(OH)2D3- or vehicle-treated chicks. We conclude that 1,25-(OH)2D3 does not change the affinity of calmodulin binding to myosin I but increases the amount of myosin I in the membrane or alters its ATP releasability. It was further investigated whether phosphorylation is involved in these 1,25-(OH)2D3 dependent posttranslational changes of myosin I. Phosphorylation of brush-border membrane proteins in vivo was performed by incubation of [32P]P(i) in the lumen of a ligated duodenal loop in situ for 15 min. Brush-border membrane proteins were phosphorylated in vitro by incubating BB or BBMV with [gamma-32P]ATP for 1 min. Incubation experiments in vivo and in vitro in fact resulted in phosphorylation of several proteins including 110 kDa proteins. However, there was no specific effect of 1,25-(OH)2D3 on phosphorylation of 110 kDa proteins. We conclude that the effects of 1,25-(OH)2D3 on protein phosphorylation are minimal and not likely to explain 1,25-(OH)2D3 stimulated calmodulin binding to ATP extractable brush-border membrane myosin I and 1,25-(OH)2D3 stimulated changes of calcium uptake across the brush-border membrane.

Crystallographic analyses of an active HIV-1 ribonuclease H domain show structural features that distinguish it from the inactive form.

. An active recombinant preparation of the carboxy-terminal ribonuclease H (RNase H) domain of HIV-I reverse transcriptase has produced crystals of several different forms, including a trigonal prism form (P3(1); a = b = 52.03, c = 113.9 A with two molecules per asymmetric unit) and a hexagonal tablet form (P6(2)22 or P6(4)22; a = b = 93.5, c = 74.1 A with one molecule per asymmetric unit). The former appears to be isomorphous with crystals of a similar, but inactive, version of the enzyme that was used for a prior crystal structure determination [Davies, Hostomska, Hostomsky, Jordan & Matthews (1991). Science, 252, 88-95]. We have also obtained a structure solution for this crystal form and have refined it with 2.8 A resolution data (R = 0.216). We report here details of our crystallization studies and some initial structural results that verify that the preparation of active HIV-1 RNase H yields a protein that is not just enzymatically, but also structurally, distinguishable from the inactive form. Evidence suggests that region 538-542, which may be involved in the catalytic site and which is disordered in both molecules in the prior structure determination, is ordered in the crystal structure of the active enzyme, although the ordering may include more than one conformation for this loop. It should also be noted that, in the crystal structure of the trigonal form, RNase H monomers associate to form noncrystallographic twofold-symmetric dimers by fusing five-stranded mixed beta sheets into a single ten-stranded dimerwide sheet, an assembly that was not remarked upon by previous investigators.

Zipper protein, a newly described tropomyosin-like protein of the intestinal brush border.

We have cloned and sequenced from a chick intestinal library the cDNA for a new tropomyosin-like protein with an extensive leucine zipper motif. The cDNA recognized a 2.5-kilobase transcript with highest levels in the intestine. The open reading frame encoded a protein with 239 residues (28 kDa), the deduced sequence of which forms 27 heptad repeats, 21 of which begin with leucine and the other 6 with conservative substitutions (methionine, valine, threonine). This sequence predicts a coiled coil dimer similar to that of tropomyosin with which it has 34% homology. We have named this newly described protein zipper protein. The protein was expressed in bacteria. Antibodies were made to peptides representing different regions of the deduced sequence and tested for their ability to recognize the recombinant zipper protein on immunoblots. Such antibodies were used to immunolocalize zipper protein to the intestinal brush border. A radioimmunoassay was then established using recombinant zipper protein as standard and tracer and one of the affinity-purified antisera as primary antibody. Extracts from intestine, kidney, and liver displaced tracer zipper protein in parallel with that of the standard curve, and zipper protein levels were readily measured in those tissues to be 2.5 +/- 0.4, 0.34 +/- 0.03, and 0.15 +/- 0.03 micrograms/mg of protein, respectively. Brain contained no detectable zipper protein. We conclude that zipper protein is a tropomyosin-like protein found predominantly in the intestinal brush border; its location and structural similarity to tropomyosin suggest a possible role in regulating the interaction of brush border myosin 1 with the actin core of the microvillus.

Limited tissue distribution of the intestinal brush border myosin I protein.

A myosinlike 105-110-kilodalton calmodulin-binding protein, brush border myosin I, found in the intestinal brush border has been linked to two seemingly disparate but possibly interacting functions of the brush border, namely, microvillar motility and vitamin D regulated calcium transport. If brush border myosin I were to function primarily as a myosinlike molecule powering cellular or microvillar motility, one might expect it to be found in a variety of tissues with microvilli such as the renal brush border and bile canaliculus. On the other hand, a more specialized function such as participation in vitamin D regulated calcium transport might dictate a more restricted tissue distribution for brush border myosin I. To determine the tissue distribution of brush border myosin I, we purified this protein to apparent homogeneity, generated antisera to it, and used the antisera to localize the protein within the intestinal epithelial cell by immunocytochemistry. We then screened a variety of other tissues (brain, lung, heart, liver, spleen, pancreas, kidney, and skeletal muscle) both for calmodulin-binding proteins as well as for brush border myosin I using Western blots and immunofluorescence. Our results indicate that the intestinal brush border myosin I is limited in its distribution to the intestinal brush border.

The Georgia diabetic retinopathy screening study.

The diabetic retinopathy screening study represents a major collaborative effort of many volunteer groups interested in decreasing the risk of severe visual loss to Georgia citizens. Results of the present study have stimulated intense interest in screening more high risk persons, such as minorities, without the exclusion of whites. While age-related macular degeneration is the predominant cause of blindness in the U.S., diabetic retinopathy is a major new cause of blindness. With the continuation and completion of this study, we believe that many more of Georgia's citizens will seek ophthalmologic examinations and benefit from previous research regarding the use of laser photocoagulation and vitreoretinal surgery in preventing or reducing the risk of blindness. Since diabetic retinopathy requiring treatment can be present in patients with normal vision, such patients should obtain an annual dilated eye examination by an ophthalmologist. The value of statewide screening for undetected diabetic retinopathy, the determination of how and where to screen in order to give the most benefit to the potentially affected individuals and citizens of Georgia are only a few of the questions that may be answered when this study is completed. Moreover, to our knowledge this study is the first statewide screening for diabetic retinopathy in the United States.

Three-dimensional structure of human serum albumin.

The three-dimensional structure of human serum albumin has been solved at 6.0 angstrom (A) resolution by the method of multiple isomorphous replacement. Crystals were grown from solutions of polyethylene glycol in the infrequently observed space group P42(1)2 (unit cell constants a = b = 186.5 +/- 0.5 A and c = 81.0 +/- 0.5 A) and diffracted x-rays to lattice d-spacings of less than 2.9 A. The electron density maps are of high quality and revealed the structure as a predominantly alpha-helical globin protein in which the course of the polypeptide can be traced. The binding loci of several organic compounds have been determined.

Calmodulin binding to the intestinal brush-border membrane: comparison to other calcium-binding proteins.

The intestinal brush-border membrane contains a high concentration of calmodulin bound to a 105,000 dalton (105 kDa) protein. Binding of radioiodinated calmodulin to this protein does not require calcium but is inhibited by trifluoperazine and excess unlabelled calmodulin. Recent evidence suggests that the 105 kDa protein in conjunction with calmodulin may be involved in the regulation of calcium transport across the brush-border membrane. In this report, we evaluated the binding of the 105 kDa protein to other radioiodinated calcium-binding proteins including the vitamin D-dependent intestinal calcium-binding protein. We observed that troponin C and S100 beta protein both bound strongly to the 105 kDa protein. The binding of S100 beta was inhibited by EGTA, but was little affected by trifluoperazine and excess unlabelled S100 beta, whereas that of troponin C was inhibited by trifluoperazine and excess unlabelled troponin C, but was little affected by EGTA. Both troponin C and S100 beta bound to a large number of proteins to which calmodulin did not bind. The vitamin D-dependent calcium-binding protein (calbindin) from chick intestine and rat kidney also bound to the 105 kDa protein, albeit more weakly than troponin C, S100 beta and calmodulin. The binding of the calbindins was increased by EGTA and was little affected by trifluoperazine and excess unlabelled calbindin. Parvalbumin, rat osteocalcin, and alpha-lactalbumin showed little binding to any brush-border membrane protein. Our results indicate that the 105 kDa calmodulin-binding protein of the intestinal brush border can bind to a variety of calcium-binding proteins all of which contain homologous regions thought to be the calcium-binding sites. Only the binding of troponin C resembles the binding of calmodulin, however, in being inhibited by trifluoperazine and excess unlabelled ligand. The functional significance of these observations in terms of regulating calcium transport across the brush-border membrane remains to be established.