O2-Hb reaction kinetics and the Fåhraeus effect during stagnant, hypoxic, and anemic supply deficit

We modified our previous computer model of O2 and CO2 transport in the cerebral microcirculation to include nonequilibrium O2-Hb kinetics and the Fåhraeus effect (reduced tube hematocrit in small microvessels). The model is a steady-state multicompartmental simulation which includes three arteriolar compartments, three venular compartments, and one capillary compartment. Three different types of oxygen deficits (stagnant, hypoxic, and anemic conditions) were simulated by respectively reducing blood flow, arterial O2 saturation, and systemic hematocrit to one half of normal. Microcirculatory distributions for PO2, PCO2, O2 saturation and deviations from equilibrium, and the O2 and CO2 fluxes for each compartment were predicted for the three O2 supply deficits. Differences were found for O2 extraction ratios and relative contributions of arteriolar, venular, and capillary gas fluxes for each type of deficit. The Fåhraeus effect and O2-Hb kinetics reduced O2 extraction in all cases and altered microcirculatory gas distributions depending on the specific type of O2 supply deficits. The modified model continues to predict that capillaries are the major site where gas exchange takes place, and demonstrates that the Fåhraeus effect and nonequilibrium O2-Hb kinetics are important mechanisms that should not be neglected in O2 and CO2 transport modeling. While this model provides useful insight regarding the influence of the Fahraeus effect and O2-Hb kinetics under steady state, the addition of a distributed and dynamic simulation should further elucidate the effects of the brain's heterogeneous properties and transient behavior.

Molecular nature of a sperm acrosomal antigen recognized by HS-13 monoclonal antibody

Among the numerous monoclonal antibodies generated against human sperm antigens, HS-13 monoclonal antibody was shown to react with an intra-acrosomal antigen from human, mouse and rat. In this study, HS-13 was used as the affinity ligand for the purification of the cognate antigen from human sperm by immunoaffinity chromatography. The purified cognate antigen from human sperm, designated as HSAg-13, was found to be a protein with a molecular weight of approximately 80 kDa on SDS-PAGE in the presence of reducing reagents. This monoclonal antibody was used as the probe to study the tissue distributions and developmental expression of the cognate antigen from human, mouse and rat by immunohistochemical assays. It was concluded that the antigen recognized by HS-13 antibody is highly sperm specific and found only in sperm and mature testis, but not in any other somatic tissues examined in human and mouse. The antigen was shown to be expressed at the postmeiotic stages of spermatogenesis in mouse and rat. By using indirect immunofluorescent staining assay, HS-13 was shown to react only with the methanol-fixed acrosome-intact sperm but not with the live sperm. Following calcium ionophore A23187 treatment, acrosome-reacted sperm showed either negative staining or residual staining in the equatorial region, suggesting the intra-acrosomal location of HSAg-13. The spontaneous acrosome reaction following overnight incubation in BWW medium resulted in a statistically significant decrease of antibody-stained human sperm. In view of excellent correlations for the scoring of acrosome-intact sperm with that of fluorescence-labeled Pisum sativum agglutinin (PSA) probe, HS-13 monoclonal antibody can be routinely used for monitoring sperm capacitation and acrosome reaction.

Characteristics of adolescent patients and their health problems at an adolescent health clinic

In Taiwan, there has been an increase in biopsychosocial morbidity among adolescents in the past ten years, but neither an adolescent health care delivery system nor a subspecialty training program in adolescent medicine has been hitherto established. To better understand the characteristics of adolescent patients and their health problems, the sociodemography and health problems of all adolescent patients aged 11 to 21 years who visited the Adolescent Health Clinic twice or more during January, 1994 and December, 1995 at a college hospital, were analysed by reviewing patients' medical records and the adolescent registration records. There were totally 264 adolescent patients with an average age of 18.7 +/- 3.4 years. The number of female adolescents involved in the study (139 persons or 52.7%) was little more than that of male adolescents. Most of the adolescent patients (67.4%) were in late stage of adolescence; in addition, most of them (81.4%) were students. During the 2-year study period, there was a total of 350 independent health problems among 957 office visits made by the 264 patients, averaging 1.3 problems and 2.7 office visits per patient and per problem, respectively. Supplementary classification, mental disorders, and respiratory system diseases were the three leading disease classifications, occupying 66.6% of all disease classifications. General medical examination, upper respiratory tract infection, and immunization were more common among all individual diagnoses. Regarding gender difference in the encountered health problems, hepatitis B, office visiting for counseling, and conductive disorder, were more prominent in the male adolescents, whereas upper respiratory tract infection, goiter, acne vulgaris, peptic ulcer disease, migraine, and eating disorders were more common in the female adolescents. Moreover, the patients in the different stages of adolescence had their unique health problems. It was concluded that there were variations in the health problems encountered among adolescents of different genders and of the different stages of adolescence.

The increase of Hodgkin's disease incidence among young adults. Experience in Connecticut, 1935-1992

BACKGROUND

Recent studies have indicated an increase in young adulthood Hodgkin's disease incidence, particularly among females, since 1970. However, no studies have examined the long term trends and period-cohort patterns of Hodgkin's disease incidence.

METHODS

The current study reported time trends and age-period-cohort patterns of Hodgkin's disease incidence during the period 1935-1992, with an emphasis on incidence rate changes among young adults, using data from the Connecticut Tumor Registry.

RESULTS

A total of 4997 incidences of Hodgkin's disease were included in the study. The authors found that the incidence of Hodgkin's disease had increased among young adults age 20-44 years. Incidence had increased dramatically among females since 1970 but less significantly among males. These observed trends were primarily associated with nodular sclerosis histologic type. Age-period-cohort analyses indicated that these observed increases in young adults were cohort phenomena, suggesting possible changes in exposure to risk factors.

CONCLUSIONS

Currently identified major risk factors, including social status, Epstein-Barr virus infection, and human immunodeficiency virus infection, cannot adequately explain the observed trends. Analytical epidemiologic studies are urgently needed to identify risk factors that will not only elucidate the etiology of Hodgkin's disease but also explain the rapid increase in Hodgkin's disease incidence among young females.

V beta 8+CD4-CD8- subpopulation induced by staphylococcal enterotoxin B

Injection of staphylococcal enterotoxin B (SEB) into BALB/c mice induced the depletion of V beta 8+ T-cells which were either V beta 8+CD4+ or V beta 8+CD8+ cells. The CD8 molecule on V beta 8+CD8+ cells was found to decrease at 72 h after SEB treatment while the V beta 8 molecule on V beta 8+ cells or CD4 molecule on V beta 8+CD4+ cells was not affected. Furthermore, a subpopulation of V beta 8+CD4-CD8- T-cells was also induced after SEB-priming. This subpopulation can be found in spleen or lymph nodes. It was small in size and constituted the major part of V beta 8+ cells in lymph nodes at 72 h after SEB-priming. Some of the V beta 8+CD4-CD8- T-cells might be autoreactive because they could be stimulated to proliferative by syngenic mitomycin C-treated splenocytes.

Fluid resuscitation attenuates early cytokine mRNA expression after peritonitis

OBJECTIVE

To study the hypothesis that fluid resuscitation alters cytokine gene expression after experimental murine peritonitis.

MATERIALS AND METHODS

Mice underwent cecal ligation and puncture (CLP) to induce peritonitis and were randomized to receive variable amounts of normal saline (0, 0.25, 1.0 ml. subcutaneously) and serum (0 or 0.1 mL) after operation. Hepatic and small intestinal (ileal) tissue were harvested at 3 or 6 hours after CLP, and total tissue RNA was extracted. Reverse transcriptase polymerase chain reaction was used to provide relative quantitation of tumor necrosis factor-alpha and interleukin (IL)-1 beta messenger RNA (mRNA) compared with beta-actin.

RESULTS

CLP without resuscitation resulted in significant increases in hepatic tumor necrosis factor-alpha mRNA (1190% at 6 hours compared with normal animals), and IL-1 beta mRNA (1475%), and intestinal IL-1 beta mRNA (1243%). Volume administration attenuated cytokine expression at both 3 and 6 hours, and saline seemed to have more potent effects than serum. The volume of resuscitation correlated with survival at 18 hours. Survival in the saline (1 mL) + serum group was 90% at 18 hours compared with 20 to 40% in the groups with little or no resuscitation. Overall, there were no survivors at 30 hours.

CONCLUSIONS

Fluid resuscitation (amount, composition, timing) should be an important consideration in the utilization of experimental infection models. Furthermore, optimization of the patient's intravascular volume status during sepsis may have important effects on immune responses, in addition to improving hemodynamic variables.

Maternal and child health services provided by the family physicians in a college hospital

Traditionally, maternal and child health services in Taiwan have been offered mainly by the public community health station in each township. There is a trend to integrate these services into the daily practice of physicians in varied medical settings. The purpose of this study was to evaluate the work of providing the maternal and child health services by family physicians practicing at a college hospital. From July 1993 through June 1994, 69 women attending the pre-marital health examination program and 399 family patients who were in need of the maternal and child health services at the Family Medicine Clinic were included in this study. Data related to subjects' backgrounds and office visits were analyzed retrospectively. About 80% of patients attending pre-marital health examinations were satisfied with the scope and process of the services provided. Of 399 family patients contacted by letter and telephone, 322 patients (80.7%) kept the appointments to visit our clinic. Regarding maternal health services, related health education and counselling services were widely provided to female family patients. However, the actual implementation rates of breast examination, Pap smear test and family planning procedures were only 44.5%, 35.7%, and 23.2%, respectively. Factors related to female patients' agreement to do breast examination or Pap smear test included their educational level, age, duration of being enrolled in family care, and the number of family members under the family care. Regarding child health services, vaccinations and periodic health examinations were the main services provided by the family physicians. We concluded that family physicians in our series are capable of providing maternal and child health services to their family patients, and that the actual implementation rates of preventive services could be further promoted through family physicians' more active attitude and recruiting methods.

Endothelin-1 expression in the small intestine during chronic peritonitis

Endothelins (ET) have been demonstrated to mediate intestinal microvascular constriction during acute Escherichia coli bacteremia, however, their role during chronic infection is unknown. The purpose of this study was to determine whether ET-1 is synthesized in the small intestine in a more chronic peritonitis model. ET-1 mRNA levels of the terminal ileum in mice following cecal ligation and puncture (CLP) were compared to sham-operated animals and normal unoperated animals. ET gene expression was analyzed using differential reverse transcriptase chain reaction (RT-PCR) with co-amplification of beta-actin as an internal standard. To assess ET peptide expression, serum and intestinal tissue levels were measured using a specific enzyme immunoassay (ELISA). The pattern of ET-1 gene expression post-CLP with a single puncture of the cecum with a 23 ga. needle demonstrated a 3.6-fold increase at 8 h, and a return to sham levels by 24 h (374 +/- 64% at 8 h, p < .05, 128 +/- 13%). An increase of mRNA levels at 24 h post-CLP was observed with a double puncture with an 18 ga. needle (230 +/- 36%, p < .05) accompanied by an increase in serum ET levels (270 +/- 31%, p < .05) and higher tissue ET levels. These data indicate a time-dependent response of ET-1 gene expression in the terminal ileum post-CLP which is related to severity of infection.

[Evaluation of the effects of a general medical course for non-medical university students]

In order to evaluate the effects of a general medical course on students' related attitudes and knowledge, 186 students who took the general medical course in the National Chung-Hsing University or the Private Fung-Chia University were asked to fill in a structured questionnaire both before and after their course during February, 1993 and January, 1994. The average age of the 177 students who completed the questionnaire on both occasions was 21.9 years; 109 were males and 68 were females. Two thirds of the students indicated that they would like to learn more about health and medical sciences as the main reason for taking the course. Before the class, the leading two perceptions of health given by students were no biopsychological problem (54.2%) and no biomedical problem (18.6%), while no biopsychological problem (55.4%) and no biopsychosocial problem (23.7%) were the leading two perceptions afterwards. After the course, about 21% of students counted health as the greatest concern in their lives, while only 16% did before the class. At first only 18.6% of students considered life style as the most important contributing factor to human health, but the frequency increased to 28.2% at the end of the class. Regarding knowledge on health and medical care, mean scores in all five domains of knowledge were significantly higher after than before the course. The general medical curriculum was welcomed and highly valued by students based on their evaluations after the class. We concluded that university students' attitudes toward and knowledge on health and medical care can be significantly increased by a general medical curriculum.

Correlation between meteorological conditions and mutagenicity of airborne particulate samples in a tropical monsoon climate area from Kaohsiung City, Taiwan

Kaohsiung is a city of 1.5 million located in the southern part of Taiwan. It has a serious air pollution problem mainly attributable to much industrial and commercial activity. In order to estimate the effects of traffic, season, and meteorological conditions on the mutagenicity of Kaohsiung City's urban ambient particulate matter, 624 airborne particulate samples were collected on a weekly basis from 12 locations for an entire year. The mutagenic potential of acetone extracts of air samples was evaluated by the Salmonella/microsomal test with S. typhimurium TA98 in the presence and absence of S9 mixtures. The air samples from November 1990 showed the highest direct and indirect mutagenicity among the 12 months, whereas those from June and July 1991 had the lowest direct and indirect mutagenic activity, respectively. The mutagenicity showed a good correlation with amounts of the acetone extractable matter of airborne particulates. The meteorological conditions, monthly mean precipitation, and wind speed also showed a good correspondence with mutagenicity. Wind direction and temperature had a moderate relationship. The major mutagenic fractions of air samples that had the highest mutagenic activity in a month were purified using Sephadex LH-20 column chromatography, and the contents of PAHs, 1-NP, and DNPs were analyzed by HPLC. The characteristic concentration ratios of PAHs indicated that, for the main pollution sources of airborne particulates from Kaohsiung city, the mobile sources were more important than the stationary ones. The total amounts of 1-NP and DNPs in airborne particulates seemed to correspond to their mutagenicity. Although the total amounts of 1-NP and DNPs in the air samples correlated with their mutagenicity, the major mutagenic chemicals in the airborne particulate samples from Kaohsiung City need further investigation.

[Surgical management of blunt renal trauma]

From 1986 to 1990, 26 patients with blunt renal trauma were hospitalized and received surgery in this Hospital. Included were 23 males and 3 females with a mean age of 28.6 years (range: 5 to 82). The mean duration of follow-up was 37 months. The severity of renal injury was classified by using the renal injury scale which was published by the Organ Injury Scaling (O.I.S.) Committee of the American Association for the Surgery of Trauma (A.A.S.T.) in 1989. According to operative findings, the renal injuries of the 26 cases were classified as follows: Grade I, 3 cases; Grade II, 4 cases; Grade III, 2 cases; Grade IV, 6 cases; and Grade V, 12 cases. One case had bilateral renal injuries. Among the patients, four were treated with drainage. Three cases underwent repair and drainage. One case was treated with partial nephrectomy. Nineteen cases underwent nephrectomy. The mortality rate was 7.6% and the morbidity rate, 15.2%. The most frequent postoperative complications related to renal injury in the patients who survived initial operation were intra-abdominal abscesses (3.8%), small bowel obstruction (3.8%), pulmonary infection (3.8%) and pancreatitis (3.8%).

The development of general practice in China

The concepts and principles of general practice are consistent with Chinese cultural values; the leading authorities at the General Practice Training Centre are extremely enthusiastic about the general practice movement; the Ministry of Public Health is totally supportive of the general practice training; the medical/allied health professionals are eager to participate in general practice activities; and general practice certainly is responsive to public expectations. General practice will be flourishing and prosperous in China; however, there may be times when the specialty of general practice in China experiences growing pains with obstacles. The experiences gained from the development of general practice training programmes in Taiwan and other countries to handle the obstacles are of tremendous value to the development of general practice in China. It is expected that communication and exchange between the general practice educators of Taiwan and China will play an important role in the further development of general practice in China.

[Surgical management of blunt abdominal trauma]

From 1986 to 1990, 175 patients with blunt abdominal trauma were hospitalized and operated on in Kuang Tien General Hospital. Included were 140 males and 35 females with a mean age of 33 years (range: 2 to 82). The mean duration of the follow-up was 42 months. We classified the severity of the injured organs with the organ injury scale which was published by the Organ Injury Scaling (O.I.S.) Committee of the American Association for the Surgery of Trauma (A. A. S. T.) in 1989 and 1990. Among the patients, 12 cases were treated with splenorrhaphy. Eighty-two cases underwent splenectomy. Four cases underwent partial resection of the liver. Three cases required repair of the inferior vena cava. Seventeen cases were treated with partial resection of the small intestine and anastomosis. Seven cases underwent colostomy. Three cases were treated with distal pancreatectomy. Nineteen cases underwent nephrectomy. One case was treated with partial nephrectomy. The mortality rate was 6.3%, and the morbidity rate 20.6%. The most frequent postoperative complications related to blunt abdominal trauma in the patients who survived the initial operation were wound infection (8.0%), small bowel obstruction (4.0%), pulmonary infection (2.3%), intra-abdominal abscesses (2.3%), pancreatitis (1.7%), pancreatic fistula (1.7%), and pseudocyst (0.6%).

[Surgical management of blunt pancreatic trauma]

From 1986 to 1990, 22 patients with blunt pancreatic trauma were hospitalized and operated on in Kuang Tien General Hospital. Included were 19 males and 3 females with a mean age of 31 years (range: 2 to 58). The mean duration of the follow-up was 42 months. We classified the severity of pancreatic injury with the pancreatic organ injury scale which was published by the Organ Injury Scaling (O.I.S.) Committee of the American Association for the Surgery of Trauma (A.A.S.T.) in 1990. According to the operative findings, the pancreatic injury of the 22 cases were classified as follows: grade I 8 cases, grade II 9 cases, grade III 4 cases, grade IV 1 case, and no grade V pancreatic injuries. Among the patients, 12 cases were treated with drainage. Seven cases underwent repair and drainage. Three cases were treated with distal pancreatectomy. The mortality rate was 18.2%, and the morbidity rate 40.9%. The most frequent postoperative complications related to the pancreatic injury in the patients who survived the initial operation were pancreatic fistula (13.7%), small bowel obstruction (9.2%), intraabdominal abscesses (4.5%), wound infection (4.5%), pancreatitis (4.5%), and pseudocyst (4.5%).

[Blunt small intestinal trauma]

From 1986 to 1990, 41 patients with blunt small intestinal trauma were hospitalized and underwent surgery in Kuang Tien General Hospital. Included were 34 males and 7 females with a mean age of 37 years (range: 8 to 67). The mean duration of follow-up was 41 months. We classified the severity of small intestinal injury with the duodenum organ injury scale or small bowel organ injury scale published by the Organ Injury Scaling (O.I.S.) Committee of the American Association for the Surgery of Trauma (A. A. S. T.) in 1990. According to the operative findings, the small intestinal injuries of the 41 cases were classified as follows: grade I-11 cases, grade II-16 cases, grade III-8 cases, grade IV-2 cases, and grade V-7 cases. Three cases had both duodenal and small bowel injuries. Among the patients, 4 cases were treated by drainage. Seven cases underwent simple repair. Three cases were treated with repair and drainage. Thirteen cases underwent enterorrhaphy and drainage. Seventeen cases were treated with resection and anastomosis. The mortality rate was 7.2%, whilst the morbidity rate was 34.0%. The most frequent postoperative complications related to the small intestinal injury in patients who survived the initial operation were wound infection (22.0%), intra-abdominal abscesses (4.8%), pulmonary infection (4.8%), and small bowel obstruction (2.4%).

Localization of transforming growth factor-alpha in adult Syrian hamster tissues

Using the cheek pouch of the Syrian hamster as an experimental model for oral carcinogenesis, it has been shown that the expression of transforming growth factor-alpha (TGF-alpha) is consistently associated with the malignant transformation process. We have recently shown that production of TGF-alpha has been localized to normal hamster oral epithelium and bone marrow eosinophils. In this study we investigated the production of this cytokine in other normal hamster adult tissues. By using an EGF-radioreceptor assay, immunohistochemistry, Northern blot analysis, and in situ hybridization we have now further detected the presence of TGF-alpha mRNA and/or protein in the kidney, stomach, and pancreas of normal adult hamster. Together with the previously reported detection of TGF-alpha in oral mucosa and bone marrow eosinophils, these adult normal tissue/cellular sources can serve as sites of TGF-alpha production. The availability of hamster specific reagents (cDNA and monoclonal antibodies) and the delineation of the various adult tissues that could produce TGF-alpha make the Syrian hamster a suitable model for the study of how this multifunctional cytokine can influence normal and pathological processes.

Job and life satisfaction among remote physicians in Taiwan

To determine the nature and current level of job and life satisfaction among remote physicians in Taiwan, 115 physicians practicing in 31 aboriginal townships and on 3 offshore islands were interviewed through a mail survey. Out of 95 respondents, 93% were male. The average age was 46.0 years, and 82% of the physicians practiced only primary care. About half of the respondents had not received any residency training prior to their beginning practice. Physicians aboriginal areas and on offshore islands appear to be moderately satisfied with their jobs and with their lives in general. In aggregate, the areas of greatest job satisfaction included their contacts with other physicians and their relationships with other health care workers. Areas of least satisfaction included physicians' salary/income and their opportunities for promotion in the future. Most respondents felt that the greatest causes of work stress were the realities of medical practice and the time pressures. Areas of least stress included clinical competence/interpersonal relations and anxieties about the future. In aggregate, the areas of lowest life satisfaction included the physicians' incomes and the lack of leisure activities. It is suggested that a family practice residency training course prior to practice and access to continuing medical education programs are urgently needed for remote physicians in Taiwan. On the other hand, economic incentives seem to be the best strategy to increase the job and life satisfaction of these physicians.

Demonstrating the characteristics of family practice through the family medicine clinic located at a college hospital

During its development, family practice in Taiwan has been housed at the university/college hospitals, and different settings have served as the main bases for service and teaching. To demonstrate the progress made in the family medicine clinic at the Chung Shan Medical College Hospital and to evaluate the appropriateness of this kind of family practice setting, our patient population of 616 was investigated. There were 5177 patient encounters during the period from September 1987 to August 1989. Of 616 patients, 52.3% were male, the average age was 38.5 years, 85.1% lived in Taichung, where the hospital is located, and 60.1% were insured. A total of 117 families, containing 310 members, made up 50.3% of the patient population. Most patients (64.0%) visited us after introductions by their relatives or friends. There was an average of 4.2 visits per patient per year, and only 6.3% of patients were lost to follow-up after their first visits. The three leading causes for visits to the Family Medicine Clinic were general medical examination (14.5%), acute upper respiratory tract infection (13.6%), and peptic ulcer diseases (8.0%): these comprised 36.1% of all patients' problems. The average referral rate among the 5177 patient encounters was 2.9%. Patient education about treatment of disease, immunization against hepatitis B, and screening for liver cirrhosis/hepatoma in hepatitis B antigen carriers were the most common preventative encounters in our clinic. In conclusion, university/college hospitals are certainly not the best site for service and teaching of family practice, since they are not based on ambulatory care.(ABSTRACT TRUNCATED AT 250 WORDS)

Small cell lung carcinoma: clinicopathological, immunohistochemical, and ultrastructural study

Sixty-seven cases of small cell lung carcinoma (SCLA) in Tri-Service General Hospital (TSGH) during the past 16 years were studied. For patients with extensive stage of disease, the mean survival time and 2-year survival rate were 7.2 months and 3.1% versus 13.4 months and 16.7% for patients with limited stage. A better prognosis was obtained by treatment with a combination of intensive chemotherapy and radiotherapy. Immunohistochemical studies were performed by the peroxidase-antiperoxidase method. The positive rates in descending order were bombesin (80%), synaptophysin (74.3%), neurofilament (68.6%), neuron-specific enolase (60%), low molecular weight cytokeratin (54.3%), high molecular weight cytokeratin (25.7%), chromogranin-A (22.9%), adrenocorticotrophic hormone (0). Seven cases were examined and found to be ultrastructure; only 3 cases were found to contain neurosecretory granules. We emphasize that electron microscopy is not necessary as a routine diagnostic procedure, while light microscopy should be employed whenever possible; the immunohistochemical study should be considered within this context.

Mutagenicity of airborne particles from four cities in Taiwan

The mutagenicity of airborne particles from 8 urban and suburban locations in each of four cities, Taipei, Hsinchu, Taichung, and Kaohsiung, in Taiwan area were investigated with S. typhimurium strain TA98 by Ames Salmonella/microsomal test. The average mutagenic activity of airborne particulate samples from Taipei and Kaohsiung was higher than that from Hsinchu and Taichung with or without metabolic activation. The major direct-acting mutagenic compounds of airborne particulate samples from Taipei and Kaohsiung was similar to that of standard dinitropyrenes mixture (DNPs) in the retention time of HPLC. Moreover, the contents of DNPs of airborne particulate samples from Taipei and automobile exhaust partially purified through Sephadex LH-20 gel filtration and semipreparative HPLC were determined by HPLC. DNPs was major direct-acting mutagens of the urban air samples from Taipei and their major pollutants might be from automobile exhaust. However, the major mutagenic compounds of airborne particulate samples from Hsinchu and Taichung did not correspond to any of the standard compounds tested. The content of benzo[a]pyrene (B[a]P) of airborne particulate samples was also determined by HPLC. The concentration of B[a] P was 0.05-0.62 ng/m3 air sample. The B[a] P contents of airborne particulate samples from four cities in Taiwan did not show good correlation with their mutagenic activity. Thus, we concluded that B[a] P was not a major indirect-acting mutagenic compound in the tested air samples.

Absence of hepatic extraction of pancreatic polypeptide in conscious dogs

In 15 conscious dogs basal portal vein pancreatic polypeptide (PP) (306 +/- 8 pg/ml) exceeded both hepatic vein PP (255 +/- 8 pg/ml) and arterial PP (244 +/- 9 pg/ml) and increased rapidly 10 min after oral glucose administration. In contrast to oral glucose, intraportal glucose infusion decreased PP levels from 45 min until the end of the infusion. Meat ingestion rapidly and promptly increased PP. During the basal state, hepatic extraction of total immunoreactive PP was 10 +/- 4%, not significantly different from zero, of the 150 +/- 14 ng/min presented to the liver. Fractional hepatic extraction of PP did not change after oral glucose, meat ingestion, or intraportal glucose infusion. Chromatographic analysis showed at least four different components of immunoreactive PP. The first peak eluted with the void volume, the second peak between the void volume and authentic PP, and the third peak coincided with authentic PP. When present, the fourth peak eluted after authentic PP. More than half of the immunoreactive PP in the basal state eluted with authentic PP, whereas about one-third was found in the second peak. The marked alterations in PP after meat, oral glucose, or intraportal glucose and atropine reflected primarily changes in the third peak. The fractional hepatic extraction of all the components was very similar.

Exposure of dog thyroid slices to acetylcholine induces refractoriness to its subsequent stimulation of glucose oxidation

An initial incubation of dog thyroid slices with 0.1 or 1 microM acetylcholine (ACH) for at least 2 h decreases its subsequent stimulation of [1-14C]glucose oxidation. Refractoriness persists for as long as 6 h in the absence of ACH. While new protein synthesis is essential for recovery, it is not necessary for its induction. Refractoriness is prevented when 25 microM tropicamide, an atropine-like drug, is present from the beginning of the initial incubation, but not when it is added after 2 h of incubation of slices with ACH, indicating that at this time ACH is no longer necessary for refractoriness. During refractoriness induced by ACH, stimulation of glucose oxidation by thyroid-stimulating hormone, prostaglandin E1, dibutyryl cyclic AMP, and cholera toxin, but not menadiol, is also significantly diminished. Incubation of thyroid slices with ACH does not modify its stimulation of iodide organification or 32Pi incorporation into phospholipids. These results suggest that the desensitization is not due to changes in the ACH receptor but rather to intracellular metabolic effects. This phenomenon may be important in the regulation of cholinergic effects on the thyroid.

Recovery from thyroid-stimulating hormone-induced refractoriness in thyroid slices: effect of removal of hormone and new protein synthesis

An initial incubation of bovine thyroid slices with TSH causes decreased responsiveness to the subsequent addition of the hormone when the adenylate cyclase -cAMP system and other metabolic parameters are measured. After the initial incubation with TSH, refractoriness persists despite incubation of thyroid slices for 24 h in the absence of added TSH. Removal of persistently bound TSH by trypsin or antibody to TSH did not reverse the refractoriness during a subsequent 2 h incubation without added TSH. However, normal TSH responsivity was restored by the removal of TSH bound during the first incubation by the addition of either trypsin or antibody to TSH at the beginning of a 24-h second incubation. Restitution of TSH responsiveness after treatment with trypsin or antibody to TSH requires new protein synthesis. While TSH-induced refractoriness does not modify stimulation of cAMP by cholera toxin, its effect on glucose oxidation is significantly diminished. Menadiol stimulation of glucose oxidation is not inhibited in thyroid slices refractory to TSH. Thus, the effect of menadiol is subsequent to the block induced by TSH, whereas that of cholera toxin is proximal to it.

The effect of tolbutamide and hepatic extraction of insulin and glucagon and hepatic glucose output in anesthetized dogs

The effects of tolbutamide and insulin infusion on hepatic extraction of insulin and glucagon and on hepatic glucose output were compared in anesthetized dogs. The basal hepatic extraction of insulin was not significantly different in the two experiments (62 +/- 7% vs. 49 +/- 8%). The fraction of insulin extracted by the liver was not changed by either tolbutamide or insulin administration. In contrast, hepatic extraction of glucagon significantly increased from a basal value of 12 +/- 8% to 41 +/- 12% 30 min after tolbutamide, coincident with hypoglycemia and increased secretion of glucagon. The percent hepatic extraction of glucagon did not change during insulin infusion despite similar hypoglycemia and an even greater increase in the amount of glucagon reaching the liver. Tolbutamide and insulin produced a transient fall in hepatic glucose output which was associated with a significant increase in the insulin to glucagon molar ratio of the portal vein. Despite the persistence of hypoglycemia, hepatic glucose production returned to control values, and the portal venous insulin to glucagon molar ratio returned toward normal. Thus, the initial hypoglycemia after tolbutamide and insulin treatment reflects decreased hepatic glucose production, while the later effects represent increased peripheral glucose utilization. Hepatic glucose output correlated better with the portal venous insulin to glucagon molar ratio than the ratio of the hormones removed by the liver. These findings indicate that insulin and glucagon extraction by the liver are quite different and are independently regulated. Tolbutamide directly increases the fraction of glucagon removed by the liver. Because of changes in hepatic extraction after tolbutamide, increased pancreatic secretion of glucagon might not be reflected in its peripheral concentration.

Time-action characteristics of regular and NPH insulin in insulin-treated diabetics

The time course of action of regular and NPH insulins injected sc was studied in 15 insulin-treated diabetics over a 24-h period during which they received a constant infusion of glucose. The blood glucose began to decline in 1.2 +/- 0.1 h (range, 0.5--2) and reached its nadir in 5.7 +/- 0.3 h (range, 4--8) after the sc injection of regular insulin. The peak effect of regular insulin usually persisted for several hours, and the total duration of action was 16.2 +/- 1.1 h (range, 9--24). Both the time of peak effect and the total duration of action were considerably prolonged compared to data provided in standard textbooks. Free insulin increased to a peak in 2.7 +/- 0.3 h (range, 1--4) after regular insulin injection and then returned to baseline by 8.8 +/- 0.96 h. Subcutaneous injection of NPH insulin decreased the blood glucose by 2.4 +/- 0.5 h (range, 1--7), with a maximal effect at 11.0 +/- 1.4 h (range, 5--19). The total duration of effect on blood glucose was 25.1 +/- 0.7 h (range, 20--29). These values are similar to those in standard textbooks. Although the total insulin levels increased after the injection of NPH insulin, there was very little if any elevation in free insulin. Recognition of the prolonged effect of regular insulin is important in establishing an insulin treatment regime for diabetic patients.

The effect of somatostatin on the hepatic extraction of insulin and glucagon in the anesthetized dog

Effects of somatostatin (250 ng/kg . min) or saline infusion on hepatic extraction of endogenous and exogenous insulin and glucagon were investigated in anesthetized dogs. After a 20-min control period, somatostatin or saline was infused into the superior mesenteric vein for 100 min. During the final 50 min of the somatostatin or saline infusion, insulin (1.7 mU/kg . min) and glucagon (20 ng/kg . min) were also infused. These infusions were then replaced with a saline infusion for an additional 30 min. Somatostatin rapidly and significantly decreased portal vein insulin and glucagon concentrations. Hepatic extraction of endogenous insulin decreased from the control value of 61 +/- 5% to 29 +/- 10% during the final 20 min of somatostatin infusion before exogenous insulin and glucagon were added to the infusion. The decrease in hepatic extraction of endogenous insulin is based on the mean of the individual values of the eight dogs in the group and may be spurious because of the very low concentrations of insulin which were being measured and the fact that at such low concentrations, some dogs appeared to have negative hepatic extraction of inulin. Glucagon extraction was unchanged (9 +/- 6% compared to 7 +/- 12%) during the first 50 min of infusion of somatostatin. Column chromatography demonstrated that the 3500 mol wt fraction of glucagon comprised 75 +/- 4% of the total glucagon immunoreactivity in the portal vein during the control period and 67 +/- 13% during the infusion of somatostatin. During the final 20 min of somatostatin infusion before the addition of insulin and glucagon, the blood glucose significantly decreased and hepatic glucose output fell from 2.4 +/- 0.4 to 1.4 +/- 0.3 mg/kg . min. However, the insulin to glucagon (3500 mol wt fraction) molar ratio did not change significantly (4.2 +/- 1.1 to 2.6 +/- 0.5). During the final 20 min of the combined infusion of somatostatin, insulin, and glucagon, hepatic extraction of insulin returned to control values and glucagon extraction rose from 7 +/- 12% to 35 +/- 11%. Hepatic glucose output increased without any significant change in the portal vein insulin to glucagon molar ratio. After the termination of the combined infusion, hepatic extraction of insulin was unchanged, but glucagon removal returned to control values. At this time, the portal vein insulin to glucagon ratio rose, and hepatic production of glucose fell below control values. These results demonstrate that somatostatin may influence peripheral insulin and glucagon values by modifying their hepatic extraction and inhibiting their pancreatic secretion. Hepatic glucose output did not always reflect the portal vein insulin to glucagon molar ratio.

Effects of thyroid-stimulating hormone on human thyroid carcinoma and adjacent normal tissue

Effects of TSH on the adenylate cyclase-cAMP system and some parameters of intermediary metabolism were investigated in human thyroid carcinoma and adjacent normal thyroid tissue. Basal adenylate cyclase activity and cAMP concentrations were significantly higher in carcinomatous tissue. Basal [1-14C]glucose oxidation, 32Pi incorporation into phospholipids, and organification of iodide were similar in both tissues. Stimulation of cAMP by TSH was significantly greater in normal compared to carcinomatous tissue. In neither tissue was there a good correlation between TSH stimulation of adenylate cyclase activity and cAMP concentrations. The TSH stimulation of 32Pi incorporation into phospholipids by TSH was significantly greater in normal tissue. The mean effect of TSH on iodide organification and glucose oxidation was similar in normal and carcinomatous tissue. Although specific binding of TSH was demonstrated in both normal and carcinomatous tissue, it did not correlate very well with stimulation of adenylate cyclase activity. Hormones other than TSH also augmented adenylate cyclase activity in two of the carcinomas. In individual patients, the relative responsivity of carcinomatous tissue compared to normal was not always consistent when all of the metabolic parameters were considered.

Hepatic insulin and glucagon extraction after their augmented secretion in dogs

Effects of intravenous arginine and cholecystokinin-pancreozymin (CCK-PZ) infusion on hepatic extraction of insulin (EI) and glucagon (EGG) and also on hepatic glucose output (HGO) were studied in anesthetized dogs. Because insulin and glucagon exert antagonistic effects on HGO, insulin:glucagon (I/GG) molar ratios were determined in the portal vein and also in peripheral vessels. During the arginine-CCK-PZ infusion the amount of insulin and glucagon coming to the liver increased 12- and 15-fold, respectively. In contrast EI decreased significantly from a control value of 62 +/- 6% to a nadir of 22 +/- 13%. EGG (control value 19 +/- 9%), however, was unaffected by arginine-CCK-PZ. The absence of any alteration in EGG cannot be attributed to the molecular heterogeneity of the immunoreactive glucagon. HGO increased fourfold in response to the pancreatic stimulation, whereas portal I/GG decreased significantly from 8.2 +/- 0.9 to 5.0 +/- 0.7. The concurrent femoral arterial I/GG (control 3.7 +/- 1.0) and mesenteric venous I/GG (control 2.1 +/- 0.5) increased significantly. These observations indicate that portal, but not peripheral, I/GG measurements reflect hepatic events in anesthetized dogs, probably because of the different extraction patterns for insulin and glucagon.