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A Ries

Publications and source records attributed to A Ries.

At least 19 recordsLinked to original sources
PubMed2001

Structural basis for the high-affinity interaction of nidogen-1 with immunoglobulin-like domain 3 of perlecan.

Nidogen and perlecan are large multifunctional basement membrane (BM) proteins conserved in all metazoa. Their high-affinity interaction, which is likely to contribute to BM assembly and function, is mediated by the central G2 domain in nidogen and the third immunoglobulin (IG)-like domain in perlecan, IG3. We have solved the crystal structure at 2.0 A resolution of the mouse nidogen-1 G2-perlecan IG3 complex. Perlecan IG3 belongs to the I-set of the IG superfamily and binds to the wall of the nidogen-1 G2 beta-barrel using beta-strands C, D and F. Nidogen-1 residues participating in the extensive interface are highly conserved, whereas the corresponding binding site on perlecan is more variable. We hypothesize that a second, as yet unidentified, activity of nidogen overlaps with perlecan binding and accounts for the unusually high degree of surface conservation in the G2 domain.

Amino Acid Sequence↗
PubMed2001

Crystal structure and mutational analysis of a perlecan-binding fragment of nidogen-1.

Nidogen, an invariant component of basement membranes, is a multifunctional protein that interacts with most other major basement membrane proteins. Here, we report the crystal structure of the mouse nidogen-1 G2 fragment, which contains binding sites for collagen IV and perlecan. The structure is composed of an EGF-like domain and an 11-stranded beta-barrel with a central helix. The beta-barrel domain has unexpected similarity to green fluorescent protein. A large surface patch on the beta-barrel is strikingly conserved in all metazoan nidogens. Site-directed mutagenesis demonstrates that the conserved residues are involved in perlecan binding.

Amino Acid Sequence↗
PubMed2001

Recombinant domains of mouse nidogen-1 and their binding to basement membrane proteins and monoclonal antibodies.

The basement membrane protein, nidogen-1, was previously shown to consist of three globular domains, G1 to G3, and two connecting segments. Nidogen-1 is a major mediator in the formation of ternary complexes with laminins, collagen IV, perlecan and fibulins. In the present study, we have produced recombinant proteins of these predicted domains in mammalian cells and used these proteins for crystallographic and binding epitope analyses. These fragments included G1, G2, the rod domain and a slightly larger G3 structure; all were obtained in good yields and were shown to be properly folded using electron microscopy. Surface plasmon resonance assays demonstrated high affinity binding (Kd = 3-9 nM) of domain G2 for collagen IV, perlecan domain IV-1 and fibulin-2, and a more moderate Kd for fibulin-1C. Domain G3 contained high affinity binding sites for the laminin gamma1 chain and collagen IV (Kd = 1 nM) and weaker binding sites for fibulin-1C and fibulin-2. A moderate binding affinity was also observed between domain G1 and fibulin-2, while no activity could be detected for the nidogen rod domain. Together, these data indicate the potential of nidogen-1 for multiple interactions within basement membranes. A similar binding repertoire was also identified for seven rat monoclonal antibodies that bound with Kd = 2-30 nM to either G1, G1-G2, G2, the rod domain or G3. Three of the antibodies showed strongly reduced binding to G2 and G3 after complex formation with either a perlecan domain or laminin-1.

Animals↗
PubMed2000

The spatial orientation of the essential amino acid residues arginine and aspartate within the alpha1beta1 integrin recognition site of collagen IV has been resolved using fluorescence resonance energy transfer.

The interaction of collagen IV with cells is mediated mainly by the integrin alpha1beta1. The recognition site has been located to a segment of the triple-helical domain 100 nm away from the N terminus of the collagen molecule. The three essential amino acid residues of the alpha1beta1 binding site, arginine alpha2(IV)461 and the two aspartate residues alpha1(IV)461, are all located on different chains. Since the spatial array of the three residues depends on the stagger of the chains within the triple helix, the stagger has been elucidated using fluorescence resonance energy transfer with phenylalanine alpha1(IV)473 and tryptophan alpha2(IV)479 as the fluorescent donor/acceptor pair. The distance R between phenylalanine and tryptophan was determined by analysis of the energy transfer efficiency, E, and the orientation factor, kappa(2). In parallel, distance R and orientation factor, kappa(2 )were also calculated from the coordinates of the triple helix. Comparison of the calculated and empirically determined values unequivocally showed the stagger to be alpha1'alpha1alpha2. This arrangement of the three alpha chains describes the conformation of the alpha1beta1 integrin recognition site, that is the distinct orientation of the side-chains of the essential residues aspartate and arginine in respect to the helix axis.

Amino Acid Sequence↗
PubMed2000

Use of the endometrial pipelle in the diagnosis of early abnormal gestations.

OBJECTIVE: To determine the sensitivity and specificity of the endometrial pipelle (Unimar, Wilton, CT) in detecting intrauterine chorionic villi, as compared to standard suction dilation and curettage (D and C). DESIGN: Prospective clinical study. SETTING: U. S. Navy Hospital near Tokyo, Japan. Small community hospital. PATIENT(S): All patients presenting for the surgical management of an early abnormal gestation were enrolled prospectively. The patient's age, gravidy, parity, estimated gestational age (EGA), diagnosis, preoperative beta human chorionic gonadotropin (betahCG) level, and preoperative transvaginal ultrasound (TVUS) data were recorded. INTERVENTION(S): An endometrial biopsy was performed in the operating room prior to standard suction dilatation and curettage (D and C). MAIN OUTCOME MEASURE(S): The presence of chorionic villi in the endometrial biopsy and curettage specimens were recorded for each patient. RESULT(S): The sensitivity of the endometrial pipelle in detecting intrauterine chorionic villi was 63% and the specificity was 80%. CONCLUSION(S): In the diagnosis of an early abnormal gestation, particularly in excluding an ectopic pregnancy, it would be ideal to replace the more invasive D and C with the outpatient endometrial biopsy in detecting intrauterine chorionic villi. However, the limited sensitivity of the endometrial biopsy limits its application in this clinical scenario. Our results compare with two previous studies and add to the limited patient database on this topic.

Adult↗
PubMed2000

Laboratory testing for preeclampsia: result trends and screening recommendations.

To better direct screening for preeclampsia, we describe the result trends of the laboratory tests used in the workup of preeclampsia at our institution. The clinical characteristics of patients with abnormal test results are further detailed. The objective of the study is to recommend a laboratory screening regimen for preeclampsia based on the data. All patients who delivered at National Naval Medical Center from February to July 1996 who had blood urea nitrogen, creatinine, aspartate aminotransferase, alanine aminotransferase, or uric acid determinations as part of a workup for preeclampsia were identified. Results are reported, and the clinical characteristics of patients with abnormal tests were obtained from the medical record. Abnormalities of uric acid and liver enzymes were few in our patient population (6% and 7%, respectively). The majority of patients with abnormal uric acid and liver function tests had the classic clinical symptoms of preeclampsia; therefore, the laboratory data added little to the clinical diagnosis. There was a high rate of renal test abnormalities, necessitating further investigation. We recommend omitting liver function and uric acid testing in the routine screening for preeclampsia. The high incidence of abnormal renal tests warrants continued use of this screening test and, more importantly, further investigation into the relationship between abnormal renal tests and disease course.

Adolescent↗
PubMed1997

Herpesvirus 6 variant A infection after heart transplantation with giant cell transformation in bile ductular and gastroduodenal epithelium.

Herpesvirus 6 (HHV-6) is a ubiquitous virus known to cause febrile syndromes and exanthema subitum in children. Less commonly, and particularly in organ transplant recipients, it may result in hepatitis, bone marrow suppression, interstitial pneunonitis, and meningoencephalitis. This report expands the spectrum of clinical disease associated with HHV-6 by documenting viral infection in a 44-year-old heart transplant recipient presenting with gastroduodenitis, pancreatitis, and hepatitis. On histopathologic examination, the gastric, duodenal, and bile ductular epithelium showed a multinucleate giant cell transformation similar to the cytopathic effect caused by the virus in human T-lymphocytes infected in vitro. Electron microscopy showed herpes particles with a thick tegument layer in the duodenum. Polymerase chain reaction amplified HHV-6 variant A sequences from multiple sites. Serology confirmed the presence of an acute HHV-6 infection. Thus, HHV-6 variant A can cause gastroduodenitis and pancreatitis in immunosuppressed individuals. Multinucleate giant cells and enveloped virions with a prominent tegument can be used as morphologic criteria to raise the possibility of HHV-6 infection in human biopsy tissue.

Adult↗
PubMed1996

The recognition sites of the integrins alpha1beta1 and alpha2beta1 within collagen IV are protected against gelatinase A attack in the native protein.

The susceptibility of three different solubilized forms of type IV collagen to gelatinase A cleavage and the concomitant effects on cell and integrin binding have been assessed. Dithiothreitol-solubilized Engelbreth-Holm Swarm (EHS) type IV collagen with disrupted intramolecular disulfide bonds in the CB3[IV] region was cleaved N-terminally to the CB3[IV] region into the two characteristic 100-300-nm fragments at 30 degrees C and was totally degraded at 37 degrees C. This was reflected in the partial or total loss of the alpha1beta1 and alpha2beta1 integrin binding sites within this region. The ability of gelatinase A to cleave EHS type IV collagen preparations with intact interchain disulfide bonds in CB3[IV] only occurred at higher temperatures. Furthermore, no effect on binding of cells or isolated integrins to the gelatinase-treated collagen could be detected after treatment at 37 degrees C. Dimeric collagen IV of human placenta with intact disulfide bonds in the CB3[IV] region was not degraded at all by gelatinase A at 37 degrees C.

Amino Acid Sequence↗
PubMed1995

The function of the NC1 domains in type IV collagen.

At its C terminus, the collagen IV molecule bears a globular NC1 domain, to which two functions have been assigned. In the macromolecular network of collagen IV, two molecules are connected via their NC1 domains, which form a hexameric complex, stabilized by intermolecular disulfide bonds. In addition, the NC1 domains are thought to be responsible for chain selection and assembly. In order to understand the role of the NC1 domains during these steps, hexameric complexes were isolated and further investigated. SDS-polyacrylamide gel electrophoresis and Western blot revealed disulfide-linked alpha 1 (IV)NC1 and alpha 2(IV)NC1 homodimers but no heterodimers. The hexamers were dissociated at low pH, separated into monomers and dimers, and submitted to reconstitution experiments. Only alpha 1(IV)NC1 dimers were able to reconstitute a hexameric complex. alpha(IV)-NC1 and alpha 2(IV)NC1 monomers as well as the alpha 2(IV)NC1 dimers showed only a low tendency to form complexes. It is assumed that during formation of the collagen IV network, lateral aggregation of the molecules via the triple helical domains brings the C termini of two molecules into close vicinity and that subsequently the weak interactions observed between the NC1 subdomains provide the correct alignment for a disulfide exchange. It is, however, questionable whether the low affinity between the NC1 subdomains alone is sufficient for chain assembly and alignment of the alpha(IV) chains before molecule formation.

Collagen↗
PubMed1995

Typhoid fever in the park: epidemiology of an outbreak at a cultural interface.

The number of reported outbreaks of typhoid fever in the United States has recently increased. Only six were reported from 1980-1989, but seven outbreaks were reported in 1990. In August 1990, health officials in Montgomery County, Maryland, were notified of two cases of typhoid fever among persons who had attended both a family picnic attended by 60 persons and a Latin Food Festival attended by 100,000 people. We obtained interviews, blood and stool cultures, and Vi serologies from attendees at and food handlers for the picnic. We defined cases as culture-confirmed or probable. Of the 60 picnic attendees, 24 (40%) had cases, of which 16 were culture confirmed. Those who ate potato salad were at increased risk of disease (17/32 vs. 6/28, relative risk [RR] = 2.5, 95% confidence interval [CI] 1.1-5.4). Picnic attendees who also attended the Latin Food Festival were not at significantly greater risk of disease than those who did not, (11/22 vs. 13/38, RR = 1.5, CI = 0.8-2.7) and we found no evidence of disease among other festival attendees. The potato salad was prepared with intensive handling and without adequate temperature control by a recent immigrant from El Salvador who was asymptomatic, did not attend the picnic, had Salmonella typhi (S. typhi) in her stool, and had elevated Vi antibodies, strongly suggestive of the carrier state. Outbreaks of typhoid fever are a threat for cosmopolitan communities. While currently available control measures are unlikely to prevent all outbreaks, thorough investigation can identify previously unrecognized carriers.

Adolescent↗
PubMed1995

Erythromycin shortens orocaecal transit time in diabetic male subjects: a double-blind placebo-controlled study.

BACKGROUND: The effects of erythromycin on small bowel motility are controversial. Orocaecal transit time (OCTT) is considered to be a valid measure of small bowel motility. METHODS: We studied the effect of erythromycin on OCTT in diabetic male subjects in a double-blind placebo-controlled crossover fashion. After an overnight fast, subjects received erythromycin 500 mg, 250 mg or placebo, on 3 different days. A standard solid meal containing 20 g lactulose was administered 30 min after the erythromycin ingestion. Exhaled breath was collected and hydrogen concentration was assessed over 5 h. Breath hydrogen concentrations for each session were analysed over time by a generalized logistic function generating a sigmoidal curve. Front transit time was recorded as the time point when a sustained rise in breath hydrogen concentration of at least 5 p.p.m. was first observed. RESULTS: The mean +/- S.E.M. time taken for the front of the meal to reach the caecum was 92.5 +/- 9.5, 86.1 +/- 16.5 and 62.3 +/- 12.1 min for placebo, erythromycin 250 mg and erythromycin 500 mg, respectively. The OCTT was significantly decreased with erythromycin 500 mg compared to placebo (P < 0.05). CONCLUSION: Oral administration of 500 mg erythromycin has prokinetic effect on orocaecal transit in male patients with diabetes mellitus.

Administration, Oral↗
PubMed1991

Characterization of a type IV collagen major cell binding site with affinity to the alpha 1 beta 1 and the alpha 2 beta 1 integrins.

The aim of this investigation was to identify the domains of type IV collagen participating in cell binding and the cell surface receptor involved. A major cell binding site was found in the trimeric cyanogen bromide-derived fragment CB3, located 100 nm away from the NH2 terminus of the molecule, in which the triple-helical conformation is stabilized by interchain disulfide bridges. Cell attachment assays with type IV collagen and CB3 revealed comparable cell binding activities. Antibodies against CB3 inhibited attachment on fragment CB3 completely and on type IV collagen to 80%. The ability to bind cells was strictly conformation dependent. Four trypsin derived fragments of CB3 allowed a closer investigation of the binding site. The smallest, fully active triple-helical fragment was (150)3-amino acid residues long. It contained segments of 27 and 37 residues, respectively, at the NH2 and COOH terminus, which proved to be essential for cell binding. By affinity chromatography on Sepharose-immobilized CB3, two receptor molecules of the integrin family, alpha 1 beta 1 and alpha 2 beta 1, were isolated. Their subunits were identified by sequencing the NH2 termini or by immunoblotting. The availability of fragment CB3 will allow for a more in-depth study of the molecular interaction of a short, well defined triple-helical ligand with collagen receptors alpha 1 beta 1 and alpha 2 beta 1.

Amino Acid Sequence↗
PubMed1990

Crystals of the NC1 domain of human type IV collagen.

Crystals of the non-collagenous C-terminal region (NC1) of type IV collagen have been obtained from human placenta. These crystals diffract to 2.0 A, and belong to space group P22(1)2(1), with cell dimensions a = 81 A, b = 158 A, c = 138 A, alpha = beta = gamma = 90 degrees. The crystals contain one hexamer in the asymmetric unit; they are very stable with respect to X-rays.

Animals↗
PubMed1990

Illustration of the effects of long-term xamoterol therapy on the time course of left ventricular pressure.

Detailed left ventricular haemodynamic investigations were performed in eight patients with New York Heart Association (NYHA) Class II heart failure, eight with NYHA Class III heart failure with an ejection fraction less than 35%, and six with severe heart failure. Xamoterol (200 mg b.d. for 3 months) caused a fall in left ventricular end-diastolic pressure, an increase in dP/dTmax and a shorter systole in all groups of patients.

Adrenergic beta-Agonists↗
PubMed1990

Anionic complex-carbohydrate units of human thyroglobulin.

Human thyroglobulin (hTG) contains sulfate in chondroitin 6-sulfate chains and in complex carbohydrates. In this study the sulfate-containing complex carbohydrates were characterized by the number of sulfate and sialic acid residues that they contain. Samples of normal and nodular thyroid tissue were incubated for 16 h in [35S]sulfate-containing medium, and hTG was purified from the tissues and the media. Complex carbohydrates were enzymatically removed from hTG. Subsequent analysis on an HPLC anion exchange column at pH 2.2 separated the carbohydrate units according to their number of negative charges. Sulfate-containing peaks were monitored by radioactivity, and sialic acid-containing peaks were identified by their shift to lower charge after treatment with neuraminidase. Peaks corresponding to sialic acid-free carbohydrate units with one to four sulfates were identified. Also, carbohydrate units with two and three negative charges containing both sulfate and sialic acid were present. In the nodular tissue of one patient there were more sulfated units with higher charge, especially units containing sialic acid. In this patient the proportion of sulfated polyvalent units with sialic acid was 22.4% for normal and 64.6% for nodular tissue. No difference in the composition of the charged units between the tissues and their corresponding media was seen, making it unlikely that the sulfate-containing carbohydrates play a role in hTG release. It is concluded that hTG contains complex carbohydrate units with up to four sulfate groups and units with both sulfate and sialic acid. In some patients, the sulfate-containing anionic carbohydrate units of hTG from normal and nodular thyroid tissue are different.

Anions↗