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Biomedical subjects

D E Klein

Publications and source records attributed to D E Klein.

At least 19 recordsLinked to original sources
PubMed2001

High-affinity binding of a FYVE domain to phosphatidylinositol 3-phosphate requires intact phospholipid but not FYVE domain oligomerization.

FYVE domains are small zinc-finger-like domains found in many proteins that are involved in regulating membrane traffic and have been shown to bind specifically to phosphatidylinositol 3-phosphate (PtdIns-3-P). FYVE domains are thought to recruit PtdIns-3-P effectors to endosomal locations in vivo, where these effectors participate in controlling endosomal maturation and vacuolar protein sorting. We have compared the characteristics of PtdIns-3-P binding by the FYVE domain from Hrs-1 (the hepatocyte growth factor-regulated tyrosine kinase substrate) with those of specific phosphoinositide binding by Pleckstrin homology (PH) domains. Like certain PH domains (such as that from phospholipase C-delta(1)), the Hrs-1 FYVE domain specifically recognizes a single phosphoinositide. However, while phosphoinositide binding by highly specific PH domains is driven almost exclusively by interactions with the lipid headgroup, this is not true for the Hrs-1 FYVE domain. The phospholipase C-delta(1) PH domain shows a 10-fold preference for binding isolated headgroup over its preferred lipid (phosphatidylinositol 4,5-bisphosphate) in a membrane, while the Hrs-1 FYVE domain greatly prefers (more than 50-fold) intact lipid in a bilayer over the isolated headgroup (inositol 1,3-bisphosphate). By contrast with reports for certain PH domains, we find that this preference for membrane binding over interaction with soluble lipid headgroups does not require FYVE domain oligomerization.

Binding, Competitive↗
PubMed1998

Specificity and promiscuity in phosphoinositide binding by pleckstrin homology domains.

Pleckstrin homology (PH) domains are small protein modules involved in recruitment of signaling molecules to cellular membranes, in some cases by binding specific phosphoinositides. We describe use of a convenient "dot-blot" approach to screen 10 different PH domains for those that recognize particular phosphoinositides. Each PH domain bound phosphoinositides in the assay, but only two (from phospholipase C-delta1 and Grp1) showed clear specificity for a single species. Using soluble inositol phosphates, we show that the Grp1 PH domain (originally cloned on the basis of its phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) binding) binds specifically to D-myo-inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4) (the PtdIns(3,4,5)P3 headgroup) with KD = 27.3 nM, but binds D-myo-inositol 1,3,4-trisphosphate (Ins(1,3,4)P3) or D-myo-inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) over 80-fold more weakly. We show that this specificity allows localization of the Grp1 PH domain to the plasma membrane of mammalian cells only when phosphatidylinositol 3-kinase (PI 3-K) is activated. The presence of three adjacent equatorial phosphate groups was critical for inositol phosphate binding by the Grp1 PH domain. By contrast, another PH domain capable of PI 3-K-dependent membrane recruitment (encoded by EST684797) does not distinguish Ins(1,3,4)P3 from Ins(1,3,4,5)P3 (binding both with very high affinity), despite selecting strongly against Ins(1,4,5)P3. The remaining PH domains tested appear significantly less specific for particular phosphoinositides. Together with data presented in the literature, our results suggest that many PH domains bind similarly to multiple phosphoinositides (and in some cases phosphatidylserine), and are likely to be regulated in vivo by the most abundant species to which they bind. Thus, using the same simple approach to study several PH domains simultaneously, our studies suggest that highly specific phosphoinositide binding is a characteristic of relatively few cases.

Animals↗
PubMed1998

The pleckstrin homology domains of dynamin isoforms require oligomerization for high affinity phosphoinositide binding.

The dynamins are 100-kDa GTPases involved in the scission event required for formation of endocytotic vesicles. The two main described mammalian dynamins (dynamin-1 and dynamin-2) both contain a pleckstrin homology (PH) domain, which has been implicated in dynamin binding to (and activation by) acidic phospholipids, most notably phosphoinositides. We demonstrate that the PH domains of both dynamin isoforms require oligomerization for high affinity phosphoinositide binding. Strong phosphoinositide binding was detected only when the PH domains were dimerized by fusion to glutathione S-transferase, or via a single engineered intermolecular disulfide bond. Phosphoinositide binding specificities agreed reasonably with reported effects of different phospholipids on dynamin GTPase activity. Although they differ in their ability to inhibit rapid endocytosis in adrenal chromaffin cells, the dynamin-1 and dynamin-2 PH domains showed identical phosphoinositide binding specificities. Since oligomerization is required for binding of the dynamin PH domain to phosphoinositides, it follows that PH domain-mediated phosphoinositide binding will favor oligomerization of intact dynamin (which has an inherent tendency to self-associate). We propose that the dynamin PH domain thus mediates the observed cooperative binding of dynamin to membranes containing acidic phospholipids and promotes the self-assembly that is critical for both stimulation of its GTPase activity and its ability to achieve membrane scission.

Amino Acid Sequence↗
PubMed1994

Access to care among children visiting the emergency room with acute exacerbations of asthma.

To determine differences in access to continuing and preventive care among pediatric patients utilizing the emergency room for treatment of acute exacerbation of asthma, families of 170 asthma patients aged 2 to 17 years were surveyed prospectively. An interview schedule instrument generated information about socioeconomic factors, source of medical care including maintenance and specialty care, medication use, and plans for management of asthma exacerbations. A primary physician or clinic could be identified by 162 patients (95%). Regular preventive therapy (cromolyn, theophylline, or steroids) was used by 45 patients (27%). Allergy evaluations had been previously performed for 59 patients (35%). "Come to Emergency Room" was part of the asthma management plan for 56 patients (33%) and was the only asthma management plan for 34 patients (20%). Logistic regression analysis found that black and Hispanic patients (odds ratio = 0.38) and patients with Medicaid (odds ratio = 0.43) were less likely to call their MD or clinic prior to reporting to the emergency room. Patients with Medicaid were more likely to have two or more prior emergency room visits compared with a group of patients with private insurance and self-paying patients (odds ratio = 4.17). While the majority of patients in this study could identify a source of primary care, patients on Medicaid were significantly less likely to access continuing and preventive care and more likely to utilize the emergency room.

Adolescent↗
PubMed1988

Computerization of the urologic office. Billing, record keeping, and education.

Careful initial evaluation of the options is vital to successful medical office automation. The many available software programs should be scrutinized to be certain the one chosen satisfies all one's listed needs. In addition to the usual functions expected of computers, the data gathered can be used to market the urologic practice. Word processing, spreadsheet, and database programs can enhance relations among the urologist's office, referring physicians, and patients.

Humans↗
PubMed1987

Changes in AIDS risk behaviors among homosexual male physicians and university students.

Two samples of homosexual men, 64 physicians and 58 university students, reported profound decreases in several sexual practices linked to transmission of acquired immune deficiency syndrome (AIDS). The physicians showed the greater reduction. When sociodemographic variables, health beliefs, feeling of control over outcome, mood, sexual interest before the AIDS epidemic, and medical care utilization were correlated with decrease and/or increase in AIDS risk behaviors, the clusters of variables most strongly correlated with change in risk behaviors differed between the physicians and students. Interventions designed to change behaviors in AIDS high-risk groups should be tailored for specific subgroups.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Non allergic rhinitis: demography of eosinophils in nasal smear, blood total eosinophil counts and IgE levels.

Seventy-eight consecutive patients with non allergic rhinitis (negative allergy skin tests) were evaluated and classified as to possible causes using strict criteria. Sixty-one percent had vasomotor rhinitis (VMR), 33% had non allergic rhinitis with eosinophilia syndrome (NARES), 16% had sinusitis, 12% had a possible hidden allergy (elevated IgE), 4% had blood eosinophilic non allergic rhinitis (BENAR) and 2% had hypothyroidism. Some overlapping of diagnosis was present. Five per cent or greater eosinophils in the nasal smear appeared to be enough to consider the diagnosis of NARES. Sinusitis tended to be more significant in the NARES group compared to VMR. BENARS may be a new syndrome. It differs from NARES in that BENARS has markedly elevated blood eosinophilia and possibly no associated sinusitis. It is similar to NARES in that it has negative allergy skin test, normal serum IgE, and eosinophils in nasal secretions. Other causes of eosinophilia were excluded in our NARES and BENARS groups.

Adolescent↗
PubMed1980

Anaphylactic reactions to Hymenoptera stings in asthmatic patients.

We evaluated 587 cases with generalized reactions to stings of Hymenoptera. Eighty of these patients and twenty-eight normal controls had radioallergosorbent tests (RAST) to venoms of honey bee, yellow jacket, hornet, wasp and to phospholipase A. Those patients with systemic reactions had a significantly greater frequency of positive RAST than normal controls (51.3% vs. 7.1%, P < 0.001). The frequency of atopy (asthma/rhinitis) in case these 587 cases was only 22% and resembled the expected frequency in a general population. Asthmatic patients did not have an increased risk of developing systemic reactions to Hymenoptera stings. However, those asthmatic patients with systemic reactions to Hymenoptera stings had a significantly more severe anaphylactic reaction to a sting than non-asthmatics. These severe reactions were primarily manifested by acute dyspnoea, which appeared to represent a bronchospastic response to endogenous histamine release.

Anaphylaxis↗
PubMed1979

Adverse reactions to cromolyn.

The frequency of adverse reactions (dermatitis, myositis, and gastroenteritis) to cromolyn sodium in asthmatic patients was 2% (B/375). Reactions were non-life-threatening and completely reversible. Immunologic evaluations, including skin and serum tests for immediate and delayed reactivity, all were negative. Adverse reactions to cromolyn do not appear to be based on an immunologic mechanism. Cromolyn appears to be a safe drug for the treatment of asthma.

Adolescent↗
PubMed1976

Significance of tartrazine sensitivity in chronic urticaria of unknown etiology.

Of 38 patients with chronic urticaria of unknown etiology who were evaluated for food and drug additive sensitivity, 53% (20/38) had urticaria for 1 yr or more. Total eosinophil counts were not elevated in most patients, and the frequency of atopy was found to be similar to that in a general population. Of these 38 patients, 10 (26%) had a personal history of aspirin intolerance, but elimination of aspirin did not relieve the urticaria. In a double-blind crossover challenge with 0.22 mg of tartrazine and a control, tartrazine sensitivity was found in 8% (3/38) of patients with chronic urticaria and 20% (2/10) of patients with aspirin intolerance.

Adult↗