Medication use characteristics in an ambulatory elderly population in Taiwan

OBJECTIVE

To compare prescribing patterns between the elderly and nonelderly in 1994, to disclose prescribing trends in the elderly-between 1992 and 1994, to explore whether drug utilization is in agreement with disease prevalence, and to identify suboptimal prescribing by drug category for ambulatory elderly patients.

DESIGN

Cross-sectional survey at two separate time intervals.

SETTING

All public group practice centers (GPCs) in Taiwan.

PATIENTS

Ambulatory adults who visited GPCs during 1 random week. Those 65 years or over were classified as the elderly group, and those 20-64 years were the nonelderly group.

MAIN OUTCOME MEASURES

Mean diagnosis, drug use, and expenditure; frequency of diagnosis; and prescribing by therapeutic category.

RESULTS

Data on 30777 elderly and 38184 nonelderly patients were collected in 1994. There was widespread use of antacids. Compared with nonelderly adults, the elderly were diagnosed with more diseases (1.3 vs. 1.2, respectively; p < 0.01), received more medications (4.7 vs. 4.1, respectively; p < 0.01), and had higher drug expenditures (5.4 vs. 4.6, respectively; p < 0.01). Chronic illness was more prevalent in the elderly, which accounted for the extensive use of cardiovascular drugs (32.1%), nonsteroidal antiinflammatory drugs (25.9%), and anxiolytics (15.9%). The upward trend in the elderly from 1992 to 1994 with hypertension (18.6% vs. 20.0%) or diabetes (9.2% vs. 10.9%) did not result in more cases of cerebrovascular disease (7.1% vs. 4.9%). There was a substantial increase in use of antispasmodic and gastroprokinetic agents (4.5% to 10.7%); the use of antacids decreased (73.6% to 63.4%) in the elderly.

CONCLUSIONS

Compared with the prevalence of disease, there was extensive nonspecific use of anxiolytics and antacids. However, lessened use of antidepressants and postmenopausal hormone replacement may have an impact on morbidity and mortality and deserves particular attention.

Comparison of cytokeratin fragment 19 (CYFRA 21-1), tissue polypeptide antigen (TPA) and carcinoembryonic antigen (CEA) as tumour markers in bronchogenic carcinoma

To elevate the diagnostic value of the serum cytokeratin 19 fragment (CYFRA 21-1) and compare it with carcinoembryonic antigen (CEA) and tissue polypeptide antigen (TPA) in bronchogenic carcinoma, the sera of 161 patients (58 with benign pulmonary disease and 103 with bronchogenic carcinoma) was investigated using immunoradiometric assay. Sensitivities for CYFRA 21-1, CEA and TPA (using 3.5 ng ml-1, 5.0 ng ml-1, 110 U l-1, respectively, cut-off values corresponding to a 95% specificity for benign pulmonary disease) in bronchogenic carcinoma were 64, 47 and 61%, respectively. Positive CYFRA 21-1 levels were identified in 75% of patients with squamous cell carcinoma (n = 36), in 67% with adenocarcinoma (n = 45), in 17% with large cell carcinoma (n = 6), and in 50% with small cell lung cancer (SCLC) (n = 16). However, CYFRA 21-1 levels were not significantly different between squamous cell carcinoma and the other histological types. The sensitivity of the combined measurement of CYFRA 21-1 with any other tumour marker was significantly higher than that of CYFRA 21-1 measurement alone. Elevated CYFRA 21-1 levels were observed in 44% of Stages I and II (n = 18) and 72% of Stage III and IV (n = 69) patients with non-small cell lung cancer (P < 0.05). A significant inter-marker correlation was observed between CYFRA 21-1 and TPA (n = 103, r = 0.448, P < 0.0001). Twenty-one patients were monitored by CYFRA 21-1, and significantly different changes in progressive patients (P = 0.0058) and regressive patients (P = 0.016) were obtained. These results indicate that CYFRA 21-1 may be not only a sensitive tumour marker in the diagnosis of bronchogenic carcinoma, but also a useful marker for the monitoring of bronchogenic carcinoma.

Profile of children requiring emergency treatment for asthma

BACKGROUND

Emergency department care for asthma is expensive and continuity of care is often inefficient. Identification of patients-at-risk for emergency treatment is required in order to intervene before visits to the emergency department.

OBJECTIVE

To identify the antecedent factors in patients requiring emergency department treatment for wheezing and to determine the level of care before emergency visits.

METHODS

A prospective survey of patients treated for wheezing in the emergency department of an academic children's hospital from January 1, 1994 to December 31, 1994. Data were compiled from a data from completed from the information obtained from the medical record, phone calls and letters.

RESULTS

During 1994, 1474 patients were treated for asthma and accounted for 1870 visits to the emergency department. Thirty-six percent of the total number of visits were made by 16% of the patients who made repeat visits. Two-thirds of the patients were 5 years of younger. Over 190 patients had been hospitalized for wheezing during the preceding 12-month period. Forty-four percent of the patients were referred to the emergency department by primary care physicians and 6.7% were referred by asthma specialists, either allergists or pulmonologists. The major predisposing factor was a family history of asthma in 70%. Beta agonists were the medications most frequently used prior to the emergency visits. Inhaled corticosteroids were used daily by 16% of the patients and oral corticosteroids were used daily by 7% of the patients.

CONCLUSION

Thirty-six percent of the visits were due to 16% of patients who were seen repeatedly in the emergency department for wheezing and a number of patients (192) had been admitted previously for wheezing. These findings suggest that there is a subset of patients who are known to have recurrent wheezing, but lack adequate management to avoid expensive hospital services. Very few of these patients were followed by asthma specialists and there was a marked underuse of anti-inflammatory drugs. This study characterized a subset of patients-at-risk for requiring emergency treatment for wheezing. There is a need to institute aggressive interventions to improve the quality of care and prevent costly emergency department visits.

The desmosome and hemidesmosome in cutaneous autoimmunity

Epidermal blister formation is the hallmark of three cutaneous autoimmune diseases: pemphigus foliaceous (PF), pemphigus vulgaris (PV) and bullous pemphigoid (BP). In PF and PV, blistering is due to acantholysis (cell-cell detachment) in the subcorneal and suprabasal epidermal layers, respectively, while BP is characterized by detachment of the basal epidermal cells from the underlying dermis. For several years, we have focused our research efforts on elucidating the pathogenic mechanisms operating in these bullous diseases. Early studies performed by our research group and others revealed that in all three diseases, the patients produce autoantibodies that bind to target antigens located on the surface of cells that are undergoing detachment. Thus it was hypothesized that these anti-epidermal autoantibodies played a role in initiating blister formation. We recognized that elucidating the normal mechanisms of epidermal cell-cell and cell-dermis adhesion would help us understand the abnormal epidermal cell detachment seen in these patients. We hypothesized that under normal conditions these adhesive mechanisms in the epidermis are complex and dynamic and mediated by the interaction of cell surface molecules unique to each layer of the epidermis. Also, we postulated that PV, PF and BP autoantibodies may cause cell detachment by impairing the function of their respective epidermal cell surfaces. Support for this hypothesis has come from recent studies which showed that PV and PF autoantibodies recognize distinct, yet related, desmosomal glycoproteins in the cadherin family of calcium-dependent adhesion molecules. The epidermal antigen in PV is desmoglein-3 (dsg3), while in PF it is desmoglein-1 (dsg1). These anti-epidermal autoantibodies have been shown to be pathogenic in passive transfer experiments. Neonatal mice injected with these antibodies develop intraepidermal blisters characteristic of the corresponding human disease. Autoantibodies in BP react with BP180 and BP230, two major components of the hemidesmosome, a cell structure involved in dermal-epidermal adhesion. Recent passive transfer mouse model studies performed in our laboratory have shown that anti-BP180 antibodies can induce subepidermal blistering in the experimental animals. Moreover, the pathogenic mechanism was shown to be dependent on complement activation and recruitment of neutrophils to the dermal-epidermal junction. In conclusion, desmosomal glycoproteins are the targets of autoimmune injury in PV and PF. The anti-epidermal autoantibodies may cause intraepidermal blisters by impairing the function of dsg1 and dsg3. In BP the hemidesmosome is the target. It appears that antiBP180 antibodies cause subepidermal blister formation by triggering a complement- and neutrophil-mediated inflammatory process.

Expression and prognostic value of proliferating cell nuclear antigen in transitional cell carcinoma of the urinary bladder

Forty-eight patients with transitional cell carcinima (TCC) of the bladder were investigated. Routine paraffin-embedded sections were stained with proliferating cell nuclear antigen (PCNA) monoclonal antibody in order to determine the growth fraction of the bladder tumors and to correlate this with tumor grade, stage, development of recurrence and survival rate during follow-up. PCNA positive staining was detected in 95.8% (46/48) of the tumors. The mean labeling index (LI) of superficial tumors (Ta-1, n = 28) was 12.58 +/- 12.33%, and 34.55 +/- 21.89% in invasive tumors (T2-4, n = 18). A similar correlation was found in association with tumor grade. The patients were followed up for a mean of 4.9 years (range 1-14 years). The mean PCNA LI in nonrecurrent (n = 21) and simple recurrent (n = 7) superficial tumors was 11.29 +/- 11.79% and 16.44 +/- 14.05%, respectively, the difference not being statistically significant. To access survival, tumors with a PCNA LI above and below the median level (21%) were compared. Those patients (n = 19) with an index of > 21% (the mean of all the PCNA values) had a worse prognosis than those (n = 27) with an index of < 21%, a difference which is statistically significant. These results suggest that PCNA LI in bladder cancer may prove to be an objective and quantitative assay of biological aggressiveness and provide significant prognostic information, although it does not help the selection of patients at risk of simple recurrence in superficial tumors.

Development and characterization of desmoglein-3 specific T cells from patients with pemphigus vulgaris

Pemphigus vulgaris (PV) is a cutaneous autoimmune disease characterized by blister formation in the suprabasilar layers of skin and mucosae and anti-desmoglein-3 (Dsg3) autoantibodies bound to the surface of lesional keratinocytes and circulating in the serum of patients. This disease can be reproduced in neonatal mice by passive transfer of patients' IgG, indicating that humoral immunity plays an important role in the pathogenesis of PV. Currently, the role of T lymphocytes in the development of PV is not clear. Here, we report that three immunoreactive segments of the ectodomain of Dsg3 specifically induced proliferation of T cells from PV patients. We found that T lymphocytes from 13 out of 14 patients responded to at least one of three Dsg3 peptides. T cells from controls and other patient groups did not respond to these Dsg3 peptides. The major T cell population stimulated by these Dsg3 peptides was CD4 positive. Dsg3-specific T cell lines and clones were developed and were shown to express a CD4 positive memory T cell phenotype. Upon stimulation, these cell lines and clones secreted a Th2-like cytokine profile. The Dsg3 responses of these T cells were restricted to HLA-DR, and not -DQ and -DP, of the major histocompatibility complex. This information will help to elucidate the cellular immune abnormalities leading to production of pathogenic IgG autoantibodies in patients with PV.

Spirometry in life-long non-smoking, healthy Chinese women in Taiwan

To establish the spirometric values for normal, healthy Chinese women in Taiwan, the spirometry of 506 life-long non-smoking, healthy Chinese women was examined, including 140 subjects over the age of 60 years. Significant correlations among age, height and forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC%, peak expiratory flow (PEF), Vmax75, Vmax50, Vmax25 were found. However, there were no significant correlations between age and FEV1/FVC%, nor age and Vmax25 in the elderly group. FEV1 (FEV1*) and FVC (FVC*) were standardized to the overall mean height for elderly women using Cole's formula. The decline in FEV1* and FVC* with age were observed. The predicted value for the average 70-year-old woman with a height of 1.5 m derived from the present study is compared with those from other surveys of the elderly. The values from the present study are somewhat higher than the values from the Hong Kong study. The authors believe the fact that all of the present subjects were life-long non-smokers might explain the differences.

Cytokeratin fragment 19 (CYFRA 21-1) as a tumor marker in non-small cell lung cancer

To evaluate the diagnostic value of the serum cytokeratin 19 fragment (CYFRA 21-1) in bronchogenic carcinoma, we investigated the sera of 138 patients (58 with benign pulmonary disease and 80 with non-small cell lung cancer (NSCLC)) using immunoradiometric assay. The mean (SD) value of serum CYFRA 21-1 in NSCLC (13.26 (16.54)) was significantly higher than in benign lung diseases (1.74 (1.55)) (p < 0.0001). Sensitivity for CYFRA 21-1 (using 3.5 ng/ml, a cut-off value corresponding to a 95% specificity for benign pulmonary disease) in NSCL was 62%. Positive CYFRA 21-1 levels were significantly higher in 75% of patients with squamous cell carcinoma (n = 36) than in 53% with other NSCLC (n = 44) (p < 0.05). CYFRA 21-1 levels were significantly different between squamous cell carcinoma (17.28 (19.94)) and the other NSCLC (9.96 (12.44)) (P < 0.05). Elevated CYFRA 21-1 levels in patients with stage III and IV disease (n = 64, 18.19 (26.51)) were significantly higher than in stage I and II (n = 16, 4.41 (5.76)) (p < 0.02). The positive rate of CYFRA 21-1 in tumor stage I and II was only 37%. Our results indicate that CYFRA 21-1 may be a useful tumor marker in NSCLC, especially in squamous cell carcinoma. However, CYFRA 21-1 cannot be used for the diagnosis of early stage disease of NSCLC. CYFRA 21-1 may also contribute to the monitoring of NSCLC.

Urinary PCO2 for hemodynamically unstable patients

BACKGROUND

Gastric intramural pH (pHi) derived from gastric PCO2 has been successfully used to assess splanchnic ischemia for patients with unstable hemodynamics, but with some limitations. Urinary bladder, also an easily accessible hollow viscus, should provide as a useful route for the same purpose. However, no study has used urinary PCO2 to evaluate the adequacy of perfusion in critically ill patients.

METHODS

Fifty patients admitted to intensive care unit were included and divided into hemodynamically stable and unstable groups. Several parameters such as arterial pressure, dopamine dosage, heart rate, serum lactate, arterial blood gas, urinary PCO2, and concentrations of Na, K and Cl in urine were measured. Patients with some other renal or pre-renal conditions that might affect urinary PCO2 were excluded.

RESULTS

Urinary PCO2 was markedly higher (78.6 +/- 9.9 vs. 43.1 +/- 1.7 mmHg, p < 0.0001) in unstable group. Serum anion gap level, dopamine dosage and heart rate were significantly higher and PaO2/FiO2 ratio as well as mean arterial pressure was lower in unstable group. Serum lactate, arterial pH and other parameters failed to distinguish between groups. Dopamine dosage significantly correlated with urinary PCO2 (r = 0.5357, p = 0.0149) in unstable group.

CONCLUSIONS

With careful selection of patients, urinary PCO2 can effectively differentiate hemodynamically unstable patients from stable ones. It also correlates significantly with dopamine dosage in patients with unstable hemodynamics.

Asynchronous DNA replication between 15q11.2q12 homologs: cytogenetic evidence for maternal imprinting and delayed replication

DNA replication kinetics of Prader-Willi/Angelman syndrome region of 15q11.2q12 was studied without synchronization in five human amniotic cell and five skin fibroblast strains with a marker 15 chromosome, i.e., 15p+ or der(15), as cytological marker to distinguish between the two homologs. BrdU-33258 Hoechst-Giemsa techniques were used to analyze and compare the late replication patterns in the 15q11.2q12 region between the homologs. Asynchronous replication between the homologs was observed in both amniocytes and fibroblasts. From cells of a marker 15 of known parental origin, the paternal 15q11.2q12 replicated earlier than that of the maternal 15 in 92%-95% of asynchronous metaphases. The remaining 5%-8% of asynchronous metaphases displayed maternal early/paternal late replication. This mosaic pattern of replication in the 15q11.2q12 region may be due to methylation mosaicism of genomic imprinting or a relative lack of self-control of replication. These results provide cytogenetic evidence of maternal imprinting and delayed replication in the 15q11.2q12 region.

Allergic bronchopulmonary aspergillosis: a case report

Aspergillus-associated pulmonary diseases are aspergilloma, invasive aspergillosis, and allergic bronchopulmonary aspergillosis. Allergic bronchopulmonary aspergillosis is caused by a complex of immunologic reactions to the presence of the Aspergillus species colonizing the bronchial trees. The disease is not common in Taiwan. The major diagnostic criteria for allergic bronchopulmonary aspergillosis are 1) bronchial asthma, 2) pulmonary infiltration, 3) peripheral eosinophilia, 4) positive skin test to Aspergillus fumigatus, 5) serum precipitin to Aspergillus fumigatus, 6) elevated serum Ig E, and 7) central bronchiectasis. We report a case who has had a chronic asthmatic-like cough for 5 years. He worked in a silo for two years before he was troubled by the disease. He was admitted to hospitals four times in the past, and received five bronchoscopic examinations and one open lung biopsy without definite diagnosis. Sputum eosinophilia directed our attention to the differentiation of eosinophilic lung diseases. A bronchogram which revealed central brochiectasis helped us to make the diagnosis of allergic bronchopulmonary aspergillosis, despite negative sputum culture for Aspergillus fumigatus and negative serum precipitin to Aspergillus fumigatus.

Prescribing patterns in primary health care in Taiwan

To identify the prescribing patterns in public group practice centers (GPCs), 84,453 prescription sheets written by primary care physicians in 168 GPCs during the period from December 7-12, 1992, were collected and analyzed. The average number of drugs per script was 4.3 and the ratio of drug to total medical expense was 44%. The 5 most common diagnoses were, in a descending order, upper respiratory tract infection, skeletomuscular and joint disease, hypertension, functional gastrointestinal disorder (including peptic ulcer) and diabetes mellitus. The top 5 most commonly dispensed drug categories were antacids and anti-ulcer drugs, anti-cough and anti-cold preparations, vitamins, simple analgesics and non-steroidal anti-inflammatory drugs, accounting for 48.8% of total prescriptions. In view of the frequency of relevant diagnoses, the overuse of antacids, vitamins, intravenous nutrient and electrolyte solutions, anti-cold preparations and antibiotics was apparent, as was that of drugs of questionable pharmacological value. These data indicate that polypharmacy is a widespread phenomenon and confirms our long-term concern over irrational drug use in GPCs in Taiwan. Both administrative and educational intervention should be implemented to improve prescribing quality at the primary health care level.

Expansion of mycobacterium-reactive gamma delta T cells by a subset of memory helper T cells

Human gamma delta T cells expressing the V gamma 9/V delta 2 T-cell receptor have been previously found to proliferate in response to certain microorganisms and to expand throughout life, presumably because of extrathymic activation by foreign antigens. In vitro expansion of V gamma 9/V delta 2 cells by mycobacteria has been previously shown to be dependent on accessory cells. In order to gain an insight into the mechanisms involved in the expansion of these cells, we have undertaken to identify the peripheral blood subset of cells on which proliferation of V gamma 9/V delta 2 cells in response to mycobacteria is dependent. Contrary to their role in antigen presentation to alpha beta T cells, professional antigen-presenting cells, such as monocytes, B cells, and dendritic cells, were unable to provide the cellular support for the expansion of V gamma 9/V delta 2 cells. Selective depletion of T-cell subsets, as well as the use of highly purified T-cell populations, indicated that the only subset of peripheral blood cells that could expand V gamma 9/V delta 2 cells were CD4+ CD45RO+ CD7- alpha beta T cells. These cells underwent distinct intracellular signaling events after stimulation with the mycobacterial antigen. Expansion of V gamma 9/V delta 2 cells by alpha beta T cells was dependent on cell-cell contact. This is the first evidence that a small subset of the memory helper T-cell population is exclusively responsible for the peripheral expansion of V gamma 9/V delta 2 cells. These data illustrate a unique aspect of antigen recognition by gamma delta T cells and provide new means to study their immune defense role.

Use of esmolol to prevent hemodynamic changes during intubation in general anesthesia

To assess the minimal effective dosage of esmolol to prevent hypertension and tachycardia during laryngoscopy and endotracheal intubation in fentanyl-pretreated anesthesia, a double-blinded, randomized study was conducted. Two hundred patients undergoing elective, noncardiac surgeries were randomly allocated into four groups: group A received saline, group B esmolol 20 mg, group C esmolol 40 mg and group D esmolol 60 mg intravenously. General anesthesia was induced with 0.1 mg/kg vecuronium, 5 micrograms/kg fentanyl and 0.3 mg/kg etomidate. Heart rates (HR), systolic blood pressures (SBP), mean arterial pressures (MAP) and diastolic blood pressures (DBP) were recorded before induction, after induction, before intubation, 30 seconds, 1 minute, 2 minutes, 4 minutes, 6 minutes, and 10 minutes after intubation. After intubation HR and SBP increased significantly in group A (86.7 beats/min, 166.6 mmHg) in comparison with groups C (77.6 beats/min, 153.9 mmHg) and D (73.4 beats/min, 153.4 mmHg) (p < 0.05). Tachycardia (HR > 100) was found in 13 of 50(26%) patients in group A, 10 of 50(20%) patients in group B, 7 of 50(14%) patients in group C and 2 of 50(4%) patients in group D. Hypertension (SBP > 180) was found in 18(36%) patients in group A, 19(38%) patients in group B, 9(18%) patients in group C, and 6(12%) patients in group D. When compared with group A, only group D had significantly lower incidence of these adverse events (p < 0.05). In conclusion, fentanyl 5 micrograms/kg could not completely prevent the hemodynamic changes associated with endotracheal intubation, and 60 mg esmolol was observed to have positive effect in helping to control these changes.

Nucleolar organizer regions in small cell carcinoma of lung

Agyrophilic staining of nucleolar organizer regions (NOR) has been used to differentiate between cells of small cell carcinoma and lymphocytes in tissue specimens. We used cytologic smears which were previously Papanicolaou-destained to study the one-step agyrophilic staining technique for nucleolar organizer regions (AgNOR) in cell of small cell carcinoma and lymphocyte. The purposes of this study were to assess the feasibility and usefulness of AgNOR staining in diagnostic cytology and to try to set up a procedure that could be used on prestained smears for retrospective study. While the NOR of each lymphocyte appeared to be one round dot after AgNOR staining, the NOR of cell of small cell carcinoma showed dots, slightly variable in size and shape. The mean number of NOR was significantly higher (p < 0.01) in cells of small cell carcinoma (4.7 +/- 0.7) than in lymphocytes (1.4 +/- 0.4). In conclusion, AgNOR staining was demonstrated to be a useful method to differentiate between cells of small cell carcinoma and lymphocyte in Papanicolaou-destained smears.

Finite element analysis of cerebral contusion

Finite element analysis was carried out to study the mechanism of cerebral contusion. Clinical findings indicate that most cerebral contusions in the absence of skull fracture occur at the frontal and temporal lobes. To explain these observations, cavitation and shear strain theories have long been advocated. Plane strain finite element models of a parasagittal section of the human head were developed in the present study. The model was first validated against a set of experimental results from the literature. Frontal and occipital impacts were then simulated, and pressure and shear stress distributions in the brain were compared. While comparable negative pressures always developed in the contrecoup regions, shear stress distributions remained nearly identical regardless of the impact direction, consistent with the clinically observed pattern for contusion. Therefore, shear strain theory appears to account better for the clinical findings in cerebral contusion.

Nucleolar organizer regions in smears of pleural effusion

Agyrophil staining was applied to nucleolar organizer regions (NOR) to differentiate cells of adenocarcinoma and histiomesotheliosis in pleural effusion. The smears were either nuclearly unstained, but cytoplasmically counterstained by Papanicolaou method or Papanicolaou-destained before agyrophil staining of nucleolar organizer regions (AgNOR). The purposes of this study were to assess the feasibility and usefulness of AgNOR staining in diagnostic cytology and to try to set up a procedure that could be used on prestained smears for retrospective study. All smears showed good background and cellular outline. The distribution of NOR was either intranuclearly or in the nucleoplasm diffusely. In previously nuclearly unstained smears, NOR showed granular to powder-like appearance. The mean number of NOR in adenocarcinoma (38.4 +/- 12.5) was significantly higher than that in histiomesotheliosis (15.6 +/- 2.9). In Papanicolaou-destained smears, the NOR showed confluent dots. The mean number of NOR was much lower as compared to that of previously nuclearly unstained smears. Furthermore, the mean number of NOR in adenocarcinoma (3.6 +/- 1.4) showed no significant difference with that of histiomesotheliosis (2.7 +/- 0.8). In conclusion, AgNOR staining is one of the methods to differentiate benign from malignant cells, but not in Papanicolaou-destained smears.

A rare 6q11+ heteromorphism: cytogenetic analysis and in situ hybridization

A rare variant of 6q11+ heteromorphism was found in a fetus and the mother during amniocentesis. The G- and Q-banding and DA/DAPI stain were negative. The C-banding was positive and the C-banded segment was 3-fold longer in the variant than in its homologue. Neither of the C-banded regions of chromosomes 6 decondensed when exposed to distamycin A or 5-azacytidine. A DNA replication study indicated that the C-banded variant was late replicating. The lateral asymmetry observed in the 6q11 variant after one replication cycle in 5-bromodeoxyuridine may result from an unequal interstrand distribution of thymidine in the repetitive DNA. Fluorescent in situ hybridization using a chromosome-6-specific alpha-satellite probe (D6Z1) demonstrated hybridization signals on the centromere of chromosome 6. The 6q11 variant showed a signal which was 3-fold larger than its homologue. These results indicate that the 6q11 variant is an amplification of a chromosome-6-specific alpha repeat, and the size of the hybridization signal correlates with the size of the laterally asymmetric and C-banded region.

Nonfatal systemic allergic reactions induced by skin testing and immunotherapy

Skin testing and immunotherapy with allergens can induce systemic allergic reactions. In order to identify factors associated with systemic allergic reactions, a prospective study was conducted from 1976-1989 with more than 10,000 patients being tested and a total of 513,368 injections being recorded. Our study showed that the probability of inducing systemic allergic reactions by skin testing was less than 0.02% and the probability of systemic allergic reactions caused by immunotherapy was 2.9%. The female to male ratio was 3 to 2. The highest incidence of systemic allergic reactions was in patients between the ages of 16 to 39 years of age. The majority of systemic allergic reactions occurred when patients were on increasing doses rather than maintenance doses. More than 95% of systemic allergic reactions were associated with pollens and most of them happened between the concentration of 100 and 1000 PNU/mL. There was no increased incidence during grass or ragweed pollination seasons in those patients who received grass or ragweed injections during the respective seasons. Only 50% of systemic allergic reactions developed within 30 minutes after injections. The three most important factors determining the incidence of systemic allergic reactions are the type of allergens, the "rate" of increase of allergen concentrations, and sensitivity of the patients to allergens. The prick test at initial allergy assessment can be used to "rule out," with a high degree of certainty, the likelihood of systemic allergic reactions. The prick test is easy to perform and it is cost-effective. Prick tests and RAST together are helpful in identifying the patients and the allergens at higher risk of systemic allergic reactions.

B cell differentiation. II. Isotype potential of a single B cell

Clonal, functionally responsive B cells are important tools for analyzing B cell activation and differentiation. Previously, we developed a method to immortalize murine B lymphoblast cells using an oncogene-carrying retroviral vector. The immortalized B cells express a cell surface phenotype similar to that of normal splenic B cells. These cells were shown to respond to B cell polyclonal mitogens and IL-4. More significantly, these cells could form conjugates with TH2 cells in the presence of a T cell superantigen. The T-B interaction promoted by the T cell superantigen resulted in B cell differentiation as demonstrated by IgM secretion and switching to IgG1 production. In this report, we analyze Ig isotype potential using two retrovirus-immortalized B cell clones. The clonality of both B cell clones was confirmed by Southern blot analysis using JH probes. It was found that anti-CD3-activated TH1 and TH2 cells promoted clonal B cells to differentiate into IgM-secreting cells. More significantly, activated TH1 cells promoted clonal B cells to switch to IgG2a production, whereas activated TH2 cells promoted clonal B cells to switch to IgG1 production. Thus, depending on which type of T helper cell a given B cell interacts with, a single B cell has the potential to switch to more than one Ig isotype. Addition of rIL-4 and anti-IFN-gamma to cultures containing TH1 and B cells resulted in IgG1 production (in addition to IgG2a production). Similarly, addition of IFN-gamma and anti-IL-4 to cultures containing TH2 and B cells resulted in IgG2a production (in addition to IgG1 production). Therefore, interaction of B cells with a given type of T helper cells could commit the B cells to a given Ig isotype. However, the presence of exogenous cytokines could divert B cells to switch to other Ig isotypes.