PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “HDM”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1992

House dust mite (HDM) antigen in naturally occurring lesions of atopic dermatitis (AD): the relationship between HDM antigen in the skin and HDM antigen-specific IgE antibody.

To elucidate the etiological role of house dust mite (HDM) antigen in the pathogenesis of atopic dermatitis (AD), we conducted immunohistochemical studies on the localization of HDM antigen in naturally occurring lesions of AD. HDM antigens were found in the epidermis and dermis in 19 of 38 cases. All of the 19 patients had HDM antigen-specific IgE antibody, but HDM antigen was not detected in the lesions of patients without HDM antigen-specific IgE or in control skin specimens. Most HDM antigens were located on Langerhans cells (LCs) or near helper T cells. Our findings suggest that HDM antigen is the causative factor in the development of eczematous lesions of AD, and thus we hypothesized that IgE-mediated allergic contact sensitivity to HDM antigen plays an important role in the pathogenesis of AD.

Adolescent↗
PubMed1992

Detection of house dust mite (HDM)-specific IgE antibodies on nasal mast cells from asthmatic patients whose skin prick test and RAST are negative for HDM.

Mast cells are found in nasal smears of pediatric patients with perennial bronchial asthma whose skin prick test and radioallergosorbent test (RAST) are negative for inhalant allergens. IgE antibodies were demonstrated on these mast cells by monoclonal anti-human IgE antibodies, whereas IgG antibodies were not detected by monoclonal anti-IgG antibodies. In order to pursue the causative allergen for asthma in these patients, binding potential between IgE antibodies on nasal mast cells and house dust mite (HDM), the most prevalent aeroallergen, was examined by an immunochemical technique. Out of 9 patients whose skin prick test and RAST were negative for HDM, 7 were found to have HDM-specific IgE antibodies on their nasal smear mast cells. None of these 7 patients had IgE antibodies to cedar pollen, a negative control aero-allergen, on their mast cells. Specific binding of HDM on the mast cells was further confirmed by the fact that nasal mast cells from patients with egg allergy bound egg white but not HDM on their surface. Preincubation of mast cells with anti-IgE antibodies inhibited binding of HDM on the mast cells, indicating that HDM was bound to surface IgE antibodies on the mast cells. These experiments enabled us to expeditiously identify sensitization to an inhalant allergen, such as HDM, in young asthmatic patients whose allergen cannot be found by conventional laboratory diagnostic procedures.

Allergens↗
PubMed1987

A haemoglobin dilution method (HDM) for estimation of blood volume variations during transurethral prostatic surgery.

A method for estimation of blood volume changes during transurethral prostatic surgery is presented (haemoglobin dilution method (HDM]. It is based on a calculation of the patient's preoperative total haemoglobin content, from which losses are subtracted. The haemoglobin concentration of the blood is used as an indicator of dilution. The HDM was compared to the 131I-RISA technique in 10 patients undergoing transurethral resection of the prostate (TUR). The difference between the HDM and RISA in estimating the total operative procedure blood volume change was 0.03 +/- 0.12 l (ns) with a linearity of 0.90. The blood volume changes were also predicted by a fluid balance formula. With RISA as reference, the formula had a lower precision (0.24 l) and a poorer linearity (0.65) than the HDM. The HDM did not lose in accuracy if repeated several times during the TURs or if a theoretical formula for estimation of the preoperative blood volume was used.

Aged↗
PubMed1992

The relationship between eosinophils, OKT6-positive cells and house dust mite (HDM) antigens in naturally occurring lesions of atopic dermatitis.

To determine the role of eosinophils in naturally occurring lesions of atopic dermatitis, we observed the distribution of eosinophil cationic protein (ECP) and the relationship between eosinophils, OKT6-positive cells and house dust mite (HDM) antigens. Some specimens showed many EG2-positive stains, although the accumulation of tissue eosinophils was not prominent. EG2 stains were seen not only in eosinophils but also in extracellular granules. Some macrophage-like cells of the dermis showed EG2 stains in the form of phagocytized eosinophil granules. Some EG2-positive eosinophils were in close contact with OKT6-positive cells in the epidermis and dermis. Furthermore, in three patients sensitive to house dust mite (HDM) antigen, HDM antigens invaded the skin with many EG2-positive stains. These results suggest that eosinophils play an active role in the development of eczematous lesions of atopic dermatitis.

Adolescent↗
PubMed1992

[Effect of treatment with HDM vaccine on selected immune parameters in children with bronchial asthma].

The purpose of the study was to trace the changes of certain parameters of humoral and cell-mediated immunity in children with asthma who received the HDM Bencard vaccine as specific immunotherapy. Among the immune parameters the levels of IgG, IgA and IgM and the phagocytosis index were determined, the E-rosette test and the HBT reduction test were done before the beginning of the treatment, after 3 months, 9 months and 3 years of desensitization. The results were subjected to statistical analysis, presented in tables and in diagrams. Of the three determined immunoglobulins only the IgG increased significantly, while the titres of IgA and IgM remained unchanged. Before desensitization the values of the per cent of T-cells in the E-rosette test were below the accepted normal level. During HDM desensitization the per cent of T-cells rose. The phagocytosis index and the NBT reduction test were lower in the asthmatic children than in healthy ones but during the treatment with HDM they reached significantly high values. These results confirmed that mechanism of the action of this immunotherapy is a complex one and influences several structures of the immune system. Raised values of the studied parameters during desensitization correlated with an evident improvement of the clinical status and marked reduction of the frequency of asthma attacks. During the treatment with the HFM vaccine no side effects of this therapy were noted.

Adolescent↗
PubMed1986

Methotrexate infusions in poor prognosis acute lymphoblastic leukemia: II. High-dose methotrexate (HDM) in acute lymphoblastic leukemia in childhood: a pilot study from April 1981.

The pilot study using HDM in all cases of ALL in childhood had been run for 4 1/2 years as of September 1985. Fourteen (23%) of all 62 diagnosed cases of ALL had WBC above 50 X 10(9)/L, all 14 achieved CR. Three of them were below one year of age, two also had WBC above 400 X 10(9)/L, the third infant had B-cell-leukemia. The remaining 11 children received our new HDM protocol (Fig. 1), one of them had relapsed (BM) as of September 1985.

Child↗
PubMed1989

[Results of immunotherapy with HDM (Bencard) in children with bronchial asthma].

Desensitization with HDM manufactured by Bencard was carried out in a group of 20 children with bronchial asthma showing hypersensitivity to Dermatophagoides pteronyssimus allergen in prick skin tests. Ten randomly selected children treated symptomatically and with climate served as a control group. Children were examined clinically before and after desensitization. Clinical improvement was observed 15 months after desensitization together with weakened delayed bronchial response to allergen inhalation. No significant difference in patency of airway was seen in both groups. Differences in serum IgE and IgG levels and mean eosinophilia in the peripheral blood were statistically insignificant.

Ascorbic Acid↗
PubMed1991

Enzymatic degradation of helodermin and vasoactive intestinal polypeptide.

Helodermin (HDM) belongs to the vasoactive intestinal polypeptide (VIP) family of polypeptides. Degradation of HDM in the tracheal tissue isolated from a guinea-pig and by an isolated enkephalinase was studied and compared with the degradation of VIP. The tracheal relaxing activity of VIP was potentiated by enkephalinase inhibitors, thiorphan and phosphoramidon, while the activity of HDM was not potentiated. On the other hand, bestatin, an aminopeptidase inhibitor, and captopril, an angiotensin converting enzyme inhibitor, did not influence the activity of VIP and HDM. The data suggests that the degradation of VIP but not HDM in the trachea was done by enkephalinase. Enkephalinase was then purified from the lung and the striatum membrane fraction through a DEAE-cellulose column, chromatofocusing column and hydroxyapatite column. The purified enkephalinase from the lung hydrolyzed VIP but not HDM. HDM and VIP were, however, hydrolyzed by the striatum enkephalinase. There was only a partial degradation of HDM by the striatum enkephalinase and the hydrolysis rate of HDM was slower than that of VIP. The degradation of VIP and HDM was inhibited by thiorphan. In conclusion, we found that VIP but not HDM was degraded by enkephalinase present in the respiratory system such as the trachea and the lung. Furthermore, enkephalinase, which hydrolyses HDM, was present in the brain.

Animals↗
PubMed1991

House dust mite sensitization in children and residential characteristics in a temperate region.

House dust mite (Hdm) infestation used to be rare in Stockholm, but Hdm-sensitized children are now frequently observed, which probably indicates an increased infestation rate. This study was performed to elucidate determinants of Hdm sensitization in children living in the area. In a case-control study, 53 Hdm-sensitized children (cases), a group of non-Hdm-sensitized atopic children (N = 54), and a group of nonallergic neighborhood children (N = 53) were included. Mattress dust was analyzed with ELISA for content of Hdm allergens. Indoor humidity and temperature were measured, and questionnaire data were collected. Asthma was significantly more common in the Hdm-sensitized group than in the atopic control group. Hdm allergens were found in 40%, 19%, and 23% of the dust samples of the case group, atopic group, and neighborhood control groups, respectively. Only 15% of the dust samples of the Hdm-sensitized children contained Hdm allergens above the recommended threshold levels of sensitization of 2000 ng/gm of dust. Inadequate ventilation, which partly appeared to be a consequence of energy saving, appeared to be a risk factor for Hdm sensitization. This result may apply also to other temperate regions and suggests that the problem is preventable.

Adolescent↗
PubMed1987

Polycation binding to glomerular basement membrane. Effect of biochemical modification.

The polycation hexadimethrine (HDM) binds to anionic sites in the glomerular basement membrane (GBM) and causes heavy proteinuria when infused in vivo. An in vitro assay of 3H-HDM binding to isolated dog GBM was developed, to permit further analysis of the GBM components binding HDM. 3H-HDM binding to isolated GBM was saturable, reversible in dose-dependent fashion by competing polycations, and inhibited by increasing salt concentration and low pH. The pH dependence of binding suggested that most of the HDM binds to carboxyl groups rather than to the sulfate groups of proteoglycans. Removal of heparan sulfate by heparinase or purified heparatinase had no detectable effect on HDM binding. Treatment of GBM with neuraminidase, hyaluronidase, or chondroitinase reduced binding of HDM by a maximum of 20 to 38%. However, substitution of carboxyl anions with nonionizable glycine methyl ester residues resulted in complete elimination of HDM binding. Parallel results were obtained in studies of glomerular localization of cationized ferritin (CatF), pI 8.5. After carboxyl substitution, GBM did not bind CatF; heparinase-treated GBM bound CatF in a distribution not demonstrably different from normal. Cellulose acetate electrophoresis of glycosaminoglycan fractions prepared from treated GBM confirmed that carboxyl modification did not alter the content or charge of the heparan sulfate of GBM, but heparinase treatment removed at least 90% of heparan sulfate. The results indicate that carboxyl groups are quantitatively more important than heparan sulfate for binding of HDM in vitro. Since HDM causes proteinuria in vivo, carboxyl groups may be important for maintenance of normal permselectivity.

Animals↗
PubMed1984

Stainable glomerular basement membrane polyanions and renal hemodynamics during hexadimethrine-induced proteinuria.

To clarify the mechanism of hexadimethrine-induced proteinuria, we studied the changes in stainable glomerular basement membrane anions and renal hemodynamics during hexadimethrine (HDM) infusion. To determine whether glomerular anions were neutralized in vivo, animals infused with HDM received cationized ferritin intravenously, or their kidneys were perfused in situ with lysozyme. During its infusion, HDM bound heavily within the glomerular basement membrane, and binding of the cationic probes was virtually abolished. During recovery after HDM infusion, HDM deposits diminished and the binding of the cationic probes recovered to normal. The inverse correlation between HDM binding and binding of the cationic probes confirms that the glomerular binding of HDM is associated with neutralization or shielding of the glomerular basement membrane anions in vivo. Renal hemodynamic parameters and urinary protein excretion rate were measured before, during, and after infusion of HDM. Heavy proteinuria appeared during HDM infusion and persisted for 1 hour after its discontinuation. Although glomerular filtration rate, renal plasma flow, and urine flow rate decreased transiently at the onset of proteinuria, they returned to baseline levels before resolution of proteinuria. Filtration fraction never changed significantly. Thus, proteinuria cannot be attributed solely to renal hemodynamic factors. These results strengthen our hypothesis that HDM induces proteinuria as a consequence of its binding to and neutralization of glomerular basement membrane fixed anions.

Animals↗
PubMed1989

Effects of a synthetic cationic polymer on sodium and potassium currents of frog nerve fibres.

(1) Voltage-clamped nerve fibres of the frog Rana esculenta were treated with the synthetic cationic polymer hexadimethrine bromide (HDM) [Polybrene]. (2) 1 microM HDM irreversibly reduced INa to about 65% of its original size. The time to peak remained almost unaffected, while the decaying phase of the currents (for pulse potentials less than -10 mV) became accelerated. The size of INa was hardly reduced further even with a 1,000-fold higher concentration of HDM. (3) The cationic polymer HDM was without effect on the voltage-dependence of activation and there was only a small shift (-4.5 mV) of the voltage dependence of steady-state inactivation. (4) Variation of [Ca2+] in the Ringer solution shifted the voltage-dependence of activation and of steady-state inactivation to the same extent before and after treatment with HDM. By contrast, 0.5 mM La3+ markedly decreased the Ca2+-induced shifts. (5) The decrease of the size of INa by increasing [Ca2+] was strongly reduced by HDM, as well as by the presence of La3+. (6) These results suggest, that HDM is bound irreversibly to Ca2+ and La3+ binding sites of the membrane that affect the size of INa. These sites are different from Ca2+ (or La3+) binding sites acting on the gating mechanism. (7) The potassium currents were also irreversibly reduced by HDM-treatment. This effect, however, was different for inward and outward currents; for inward currents the IK remaining was about 20% of its original size, while for outward currents IK was reduced only to about 65%. The time course of activation of IK was not affected by HDM-treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

A comparison of protein synthetic patterns of MDCK cells grown in serum and hormonally defined serum-free medium.

The development of hormonally defined serum-free media (HDM) for the culture of mammalian cells has allowed the study of specific cellular functions in a totally defined environment. Recently, several reports have indicated that there are differences in the basic cellular physiology of cells cultured in HDM when compared to cells cultured by the more traditional method of using serum-supplemented culture media (SM). We report here that there are significant changes in the protein synthetic pattern in MDCK cells grown in HDM. There were no changes exhibited during the first passage in HDM, but following 10 passages in HDM there was an increased isotope ratio of 1) plasma membrane proteins with molecular weights of 12,000, 36,000 and 68,000 and 2) endoplasmic reticulum proteins with molecular weights of 12,000 and 37,000. Additionally, the incorporation of methionine and uridine were significantly increased in cells cultured in HDM for 10 passages. At present, we believe that these changes in the protein synthetic patterns are due at least partially to increased protein synthesis as indicated by monosome/polysome ratios. Therefore, though the use of HDM offers a completely defined system for studying cellular function, results obtained using HDM must be interpreted with caution when comparing them to previous studies that have used SM.

Animals↗
PubMed1986

Influence of plating density on individual cell growth, cell division and differentiation of neonatal rat heart primary cultures.

The influence of plating cell density of an originally enriched myocardial cell population has been studied in neonatal rat heart cells in culture. Low density (LDM) is defined as a density (24 h after plating) of 209 +/- 44 cells/mm2 (mean +/- SEM) and is compared with high density (HDM), 419 +/- 67 cells/mm2. Cell growth is evaluated by the total cell number, the percentage of myocardial cells (M) in culture (PAS method) and the protein content per cell. Some differentiation parameters such as beating rates, glycogen concentration, enzymatic activities (cytochrome C oxidase and glycogen phosphorylase) are studied with time in culture (48, 96 and 192 hr). High density was designed to yield a complete confluency of the cells within 24 hr after plating and to minimize cell division of the non-muscle cells (F). At high density, cell division of F cells is effectively limited, thus leading to a more stable model regarding the cell density per plate and the percentage of M cells: 85.7 +/- 4% and 33.4 +/- 6% in LDM cultures compared with 86.5 +/- 4.7% and 51.7 +/- 9.8% in HDM cultures at 24 and 192 hr (mean +/- SEM). Heart cells increase similarly in size with age in culture in both groups. In HDM cultures the spontaneous contractions begin sooner (24 hr) than in LDM cultures and are more rapidly synchronized. The beating rate is higher in HDM cultures between 48 and 96 hr; however, after this time it falls in HDM and does not fall in LDM. Thus the overgrowth of muscle cells by non-muscle cells is not responsible for loss of beating with time in culture but more likely high density could be a limiting factor for isotonic contraction. There is more glycogen per myocyte in LDM than in HDM cultures. The cell density influences the enzymatic activities of cytochrome C oxidase and glycogen phosphorylase. The cytochrome oxidase activity is higher in HDM cultures than in LDM cultures at 96 hr whereas glycogen phosphorylase activity is higher in LDM cultures at time 96 and 192 hr. In LDM cultures, the ratio cytochrome C oxidase/glycogen phosphorylase decreases with time in culture from 1.685 +/- 0.680 at 48 hr to 0.780 +/- 0.290 at 192 hr but not in HDM cultures (2.13 +/- 0.36 and 1.64 +/- 0.34 respectively). Thus plating density influences properties of heart cell cultures with regard to the overgrowth of the F-cell population and the differentiated state of M cells.

Aminosalicylic Acid↗
PubMed1988

A study of the role of house dust mite in atopic dermatitis.

Subjects with positive skin-prick tests to house dust mite (HDM) solution, including those with and without atopic dermatitis, participated in a double-blind, controlled study of the role of HDM exposure in the pathogenesis of atopic dermatitis. HDM solution and diluent control were applied daily to mildly eczematous or clinically uninvolved skin of the antecubital or popliteal fossae, without prior abrasion, for 5 days. Responses were assessed by a clinical grading system and by measurement of area of dermatitis; pruritus was recorded on visual analogue scales. The clinical grading system showed that marked or moderate delayed local reactions developed in one third of patients with atopic dermatitis in response to HDM application to both mildly eczematous and clinically uninvolved skin. Relative to control sites, significant increases in area of dermatitis and degree of pruritus were also recorded in response to HDM application to mildly eczematous sites. Application of HDM solution to normal, unabraded skin of prick test positive subjects without a history of dermatitis, produced pruritus and immediate urticarial responses which were not seen at control sites, findings which demonstrate that HDM antigen may be rapidly absorbed in normal skin. Application of vehicle or antigen solution to which subjects were negative on prick testing, produced no significant local reactions. This study provides objective evidence for a role for cutaneous HDM exposure in the pathogenesis of atopic dermatitis.

Adolescent↗
PubMed1991

Reversible hexadimethrine-induced alterations in glomerular structure and permeability.

Female Munich-Wistar rats received hexadimethrine (HDM) i.v. until the onset of proteinuria (PEAK)--a period of not more than 30 min. There were four experimental groups: C (control), H (HDM only), HH (HDM and heparin), and HHD (identical to HH but with dextran clearances measured). Rats in groups HH and HHD received a heparin bolus after the PEAK period, whereas rats in group H did not. HDM led to dramatic increases in both albumin and IgG excretion. Glomerular filtration rate and renal plasma flow rate were reduced by 30 to 50% after HDM infusion. Neutral dextran clearances for radii greater than 30 A were elevated during the PEAK period, and, concurrently, there was extensive intraglomerular microthrombosis, obliteration of foot processes, and disruption of filtration slit diaphragms. One hour later, glomerular filtration rate, renal plasma flow rate, dextran clearances, and proteinuria returned to baseline in groups HH and HHD but not in group H. Recovery in heparin-treated rats was associated with reversal of HDM-associated morphological alterations. Membrane pore-size parameters calculated from the dextran clearances indicate that HDM leads to a detect in glomerular size-selectivity. The facts that maximal albuminuria tended to precede maximal excretion of IgG and that increases in albumin excretion were proportionately greater than those of dextran or IgG suggest that HDM also leads to a time-dependent defect in glomerular charge-selectivity.

Albuminuria↗