Seroepidemiological study of Toxoplasma gondii infection in the rural area Okcheon-gun, Korea

There have been some reports about the prevalence of anti-Toxoplasma gondii antibody among Koreans, and most of all data were taken from patients visiting hospitals. However, the epidemiological data of the community-based study in Korea are rare. This study was performed to evaluate the seroprevalence of toxoplasmosis among the inhabitants of the rural area Okcheon-gun, Korea. A total of 1,109 serum samples (499 males, 610 females) were examined for the IgG antibodies by ELISA. To set up the cut-off point for ELISA, we used a commercial latex agglutination (LA) kit. The sensitivity and specificity of ELISA against LA test were 89.5%, and 98.6% respectively. Among 1,109 sera, 6.9% showed seropositivity by ELISA. The positive rates of males and females were 6.0% and 7.2%, respectively. However, there were no significant differences between sexes. Comparing the age groups, the highest seropositive rate showed in the seventies or higher, and their rates had a tendency to increase with age (0.05 < p < 0.3). These results revealed that the seroprevalence of toxoplasmosis in rural inhabitants is similar to previous reports in Korea; however we need further investigation to clarify the prevalence of toxoplasmosis in the general population.

Hypersensitivity pneumonitis caused by Fusarium napiforme in a home environment

BACKGROUND

We report a case of hypersensitivity pneumonitis (HP) in a 17-year-old male student caused by Fusarium napiforme found in his home environment.

METHODS

The patient was diagnosed according to history, chest radiograph, spirometry, high-resolution chest CT, and transbronchial lung biopsy. To identify the causative agent, cultured aeromolds were collected by the open-plate method. From the main fungi cultured, fungal antigens were prepared, and immunoblot analysis with the patient's serum and each fungal antigen was performed.

RESULTS

Five fungal species were isolated from the patient's home. Immunoblotting analysis with the patient's serum demonstrated more than 10 IgG-binding fractions to F. napiforme extract only, while little binding was noted with the other fungal antigens.

CONCLUSIONS

We should be aware that HP may be caused by F. napiforme in the home environment.

Modulation of Nad(P)H:quinone oxidoreductase (NQO1) activity mediated by 5-arylamino-2-methyl-4,7-dioxobenzothiazoles and their cytotoxic potential

Synthesized 5-arylamino-2-methyl-4,7-dioxobenzothiazoles 3a-3o were evaluated for modulation of NAD(P)H: quinone oxidoreductase (NQO1) activity with the cytosolic fractions derived from cultured human lung cancer cells and their cytotoxicity in cultured several human solid cancer cell lines. The 4,7-dioxobenzothiazoles affected the reduction potential by NQO1 activity and showed a potent cytotoxic activity against human cancer cell lines. The tested compounds 3a, 3b, 3g, 3h, 3n and 3o were considered as more potent cytotoxic agents, and comparable modulators of NQO1 activity.

Transient expression of transglutaminase C during prenatal development of human muscles

Tissue transglutaminase (TGase C, TGase II) is known to participate in cellular processes during morphogenesis, differentiation, and development of various prenatal tissues and organs. The expression of TGase C during myoblast proliferation and attachment to external laminae was examined by immunohistochemical (IH) localization at 5-12 weeks of developmental stages of prenatal human muscle in 23 embryos. IH detection using a monospecific antibody to TGase C showed a prominent expression of TGase C in muscle cells as stage- and spatial-specific patterns during an early embryonal period. The myoblasts of intervertebral, tongue, and limb muscles, attached to adjacent cartilaginous skeletons or fibrous fascia, showed a pronounced expression of TGase C at 5-6, 6-7, and 7-8 weeks after fertilization, respectively. The most intense activity of TGase C was observed in some cardiac myoblasts infiltrating into endocardial mesenchyme at 6-7 weeks after fertilization. Although weak staining was detected until 14 weeks after fertilization, the level of TGase C expression in all muscles was significantly decreased after 6-7 weeks, with the exception that the smooth muscle cells of blood vessels and gastrointestinal tract showed diffusely intense staining of TGase C between 5 and 12 weeks after fertilization. Western blotting analysis of the cellular extracts of pooled samples showed a single strong band at 80 kD at 6 weeks after fertilization. This band became weaker after 8-10 weeks of prenatal development. These findings of transient expression of TGase C, which coincides with the development of myoblast anchoring and differentiation, suggest that TGase C plays a role in myoblast attachment to the extracellular laminae during the early embryonal period.

Tumor vessel: a valuable cholangioscopic clue of malignant biliary stricture

BACKGROUND

An irregularly dilated and tortuous vessel, the so-called tumor vessel, is considered to be one of the cholangioscopic features that suggest biliary malignancy. This is a prospective analysis of the presence of a tumor vessel as a finding that discriminates between benign and malignant biliary strictures.

METHODS

From August 1997 to August 1998, a total of 63 patients with biliary strictures diagnosed with endoscopic retrograde cholangiography or percutaneous transhepatic cholangiography obtained during percutaneous transhepatic biliary drainage tube placement were included in this study. Strictures were characterized as benign or malignant based on the observation of tumor vessels. The results were compared with those of percutaneous transhepatic cholangiography-guided biopsy and final diagnosis.

RESULTS

Forty-one patients were confirmed to have malignant strictures and 22 had benign biliary strictures. Cancer was confirmed by histopathologic evaluation of biopsies in 33 of 41 patients with malignancy (80.4%). Tumor vessel was seen in 25 of 41 patients with malignancy (61%). No patients with benign stricture had tumor vessels. Of the 8 patients with negative percutaneous transhepatic cholangioscopy-guided biopsies but with a final diagnosis of malignancy, 6 had tumor vessels. Combining the observation of tumor vessel and percutaneous transhepatic cholangiography-guided biopsy resulted in a diagnosis of malignancy in 39 of 41 patients (96%) and significantly increased the rate of preoperative diagnosis when compared with percutaneous transhepatic cholangiography-guided biopsy or presence of tumor vessel alone (p<0.05).

CONCLUSION

The presence of tumor vessel may be a valuable cholangioscopic finding that indicates the presence of a malignant biliary stricture. The combination of tumor vessel observation and percutaneous transhepatic cholangiography-guided biopsy may improve the preoperative diagnosis of malignancy.

Optical biosensing of nitrite ions using cytochrome cd1 nitrite reductase encapsulated in a sol-gel matrix

Nitrite is an important human health and environmental analyte. As such, the European Union (EU) has imposed a limit for nitrite in potable water of 0.1 mg l-1 (2.18 microM). In order to develop an optical biosensing system for the determination of nitrite ions in environmental waters, cytochrome cd1 nitrite reductase has been extracted and purified from the bacterium Paracoccus pantotrophus. The protein has been spectroscopically characterised in solution and important kinetic parameters of nitrite reduction of the cytochrome cd1 enzyme, i.e., Km, Vmax and kcat have been determined. The influence of pH on the activity of the cytochrome cd1 has been investigated and the results suggest that this enzyme can be used for the determination of nitrite in the pH range 6-9. Biosensing experiments with the cytochrome cd1 in solution suggested that the decrease in intensity of the absorption band associated with the d1 haem (which is the nitrite binding site), at 460 nm, with increasing nitrite concentrations would enable the measurement of this analyte with the optimum limit of detection. The cytochrome cd1 has been encapsulated in a bulk sol-gel monolith with no structural changes observed and retention of enzymatic activity. The detection of nitrite ions in the range 0.075-1.250 microM was achieved, with a limit of detection of 0.075 microM. In order to increase the speed of response, a sol-gel sandwich thin film structure was formulated with the cytochrome cd1. This structure enabled the determination of nitrite concentrations within ca. 5 min. The sol-gel sandwich entrapped cytochrome cd1 enzyme was found to be stable for several months when the films were stored at 4 degrees C.

Safety and usefulness of percutaneous transhepatic cholecystoscopy examination in high-risk surgical patients with acute cholecystitis

BACKGROUND

The aim of the present study was to evaluate the diagnostic and therapeutic usefulness of percutaneous transhepatic cholecystoscopy in high-risk surgical patients with acute cholecystitis.

METHODS

Between January 1992 and June 1998, there were 33 consecutive patients who underwent percutaneous transhepatic cholecystostomy and subsequent percutaneous transhepatic cholecystoscopy for the management of acute cholecystitis.

RESULTS

Percutaneous transhepatic cholecystostomy and subsequent percutaneous transhepatic cholecystoscopy were successfully accomplished in all 33 patients. During percutaneous transhepatic cholecystoscopy, minor complications (2 episodes of minor bleeding during electrohydraulic lithotripsy, 2 of tube dislodgement, and 1 of bile leakage to peritoneum) occurred in 5 patients. Percutaneous transhepatic cholecystoscopy revealed gallstones in 26 cases, sludge ball in 3, gallbladder carcinoma in 3, and 1 case of clonorchiasis related with acute cholecystitis. The 3 gallbladder cancers which were not identified radiologically were found incidentally during percutaneous transhepatic cholecystoscopy. For the 26 patients with gallstones, percutaneous transhepatic cholecystoscopy and concomitant stone removal were successful in 1 to 4 consecutive sessions (mean 2.2 sessions). Gallstones recurred in 3 of 22 patients (14%) during the mean follow-up period of 27 months. All of them remain asymptomatic.

CONCLUSION

Percutaneous transhepatic cholecystostomy may be justified in the management of acute cholecystitis in selected patients with high surgical risk.

Variations in practice and outcomes in the Canadian NICU network: 1996-1997

BACKGROUND

Previous reports of variations in outcomes among neonatal intensive care units (NICUs) examined only specific subpopulations of interest (eg, very low birth weight [VLBW] infants <1500 g of birth weight [BW]).

OBJECTIVES

We report on current practice and outcomes variations in a population-based national study of Canadian NICUs from January 8, 1996 to October 31, 1997.

METHOD

Information on 20 488 admissions to 17 tertiary level NICUs across Canada was prospectively collected by trained abstractors using a standard manual of operations and definitions. Data were verified and analyzed in concert with a steering committee comprising experienced researchers and neonatologists. Patient information included demographic information, antenatal history, mode of delivery, problems at delivery, status of infant and problems at birth, illness severity (Clinical Risk Index for Babies, Score for Neonatal Acute Physiology, Score for Neonatal Acute Physiology-Version II), therapeutic intensity (Neonatal Therapeutic Intensity Scoring System [NTISS]), selected NICU practices and procedures, use of technology and resources, and selected patient outcomes. Patients were tracked until death or discharge home.

RESULTS

The mean number of annual admissions to an NICU was 657, with 26% outborn infants. Fifty-three percent were <2500 g BW, 20% were <1500 g BW (VLBW), and 65% were preterm (<38 weeks' gestational age [GA]). Only 2% of mothers received no prenatal care. Antenatal steroids were given to 58%, but there was wide variation in use (23%-76%). Congenital anomalies were present in 14%, and 4% were small for GA (less than the third percentile). Admission illness severity was lowest among infants 33 to 37 weeks of GA and correlated with risk of death. Ninety-six percent of patients survived until discharge, but fewer survived at lower GA. No infant <22 weeks' GA survived. Seven percent of infants had at least 1 episode of infection, but 75% received antibiotics in the NICU. Forty-three percent received respiratory support, and 14% received surfactant. Nitric oxide was given to 150 term infants and to 102 preterm infants. Selected outcomes of VLBW infants were: survival rate (87%); chronic lung disease (26%); >/=stage 3 retinopathy of prematurity (ROP; 11%); >/=grade 3 intraventricular hemorrhage (IVH; 10%); nosocomial infection (22%); necrotizing enterocolitis (NEC; 7%). Sixty-nine percent of VLBW infants survived without major morbidity (>/=grade 3 IVH, chronic lung disease, NEC, >/=grade 3 ROP). The mean duration of NICU stay was 19 days. Forty-seven percent of infants were discharged from the hospital, and 43% were retrotransferred to a community facility before discharge home. Significant variation in practices and outcomes were observed in all aspects of NICU care.

CONCLUSION

This study provides population-based information about NICU outcomes. Significant variation in NICU practices and outcomes was observed despite Canada's universal health insurance system. This national database provides valuable information for planning research, allocating resources, designing health and public policy, and serving as a basis for longitudinal studies of NICU care in Canada.

Cholangioscopic findings in bile duct tumors

BACKGROUND

Cholangioscopy has been used in the treatment of bile duct stones and the diagnosis of various bile duct tumors. However, the cholangioscopic characteristics of the various types of bile duct tumors have not been clearly described. We analyzed the results of cholangioscopic examinations and classified the findings according to tumor histology.

METHODS

Cholangioscopic findings from 111 patients with benign or malignant bile duct tumors were reviewed. The mucosal changes, the presence of neovascularization, and the patterns of luminal narrowing were analyzed and compared with the histologic diagnosis.

RESULTS

Bile duct adenocarcinoma can be classified into 3 different types according to the cholangioscopic findings: nodular, papillary, and infiltrative. Bile duct adenoma, hepatocellular carcinoma and other types of bile duct cancer such as mucin-hypersecreting cholangiocarcinoma, biliary cystadenocarcinoma, and squamous cell carcinoma also presented unique cholangioscopic characteristics.

CONCLUSIONS

Bile duct tumors exhibit characteristic cholangioscopic findings and cholangioscopy seems to be useful for differential diagnosis.

Neurogenic intermittent claudication related to spinal stenosis

BACKGROUND

The pathophysiology of neurogenic intermittent claudication (NIC) is not very well understood. We examined the theory of "two-level" spinal stenosis as the pathologic cause of NIC.

METHODS

Forty-five consecutive patients with NIC were chosen for the study group and another 45 patients with chronic low back pain, but without NIC, were consecutively chosen for the control group. All the patients were examined using several methods that included a personal history survey, physical examination, X-ray studies, computed tomography (CT) and magnetic resonance imaging (MRI).

RESULTS

Two-level central canal stenosis was found on MRI in 88.9% of the study group compared to only 37.8% of the control group (Fisher's exact two-tailed test, P = 0.0000). In the study group, 77.8% of the patients had severe or moderate facet joint degeneration on CT. The remaining 22.2% of patients had mild facet joint degeneration. In the control group, 40% of the patients had severe or moderate facet joint degeneration, while it was mild or normal in the remaining 60% (Fisher's exact two-tailed test, P = 0.0005). On X-ray, 42.2% of the study group compared with 17.7% of the control group had spondylolisthesis (Fisher's exact two-tailed test, P = 0.0129). In 35% of the study group compared with 11.1% of the control group, X-ray findings showed scoliosis (Fisher's exact two-tailed test, P = 0.0115). The lumbosacral angle in the study group was 35.8 degrees +/- 6.1 degrees compared to 33.1 degrees +/- 7.5 degrees in the control group (independent Student's two-tailed t-test, P > 0.05).

CONCLUSIONS

Our study strongly supports pathophysiology for NIC that is closely related to two-level spinal canal stenosis. Degenerative joint disease, spondylolisthesis and scoliosis of the lumbar spine are predisposing factors of NIC.

The clinical usefulness of ictal surface EEG in neocortical epilepsy

PURPOSE

Localizable scalp EEGs, during ictal episodes, appear to be rare in neocortical epileptic syndromes. However, studies based on large numbers of patients are also rare. This study aims to identify the characteristic patterns of variable neocortical epilepsies and to evaluate their clinical usefulness in the localization of epileptogenic focuses.

METHODS

We retrospectively assessed 394 noninvasive ictal recordings from 86 patients who subsequently underwent invasive study and resective surgery. Ictal EEGs were recorded using a video-EEG monitoring system with electrodes placed according to the International 10-20 system, with additional anterior temporal electrodes. The ictal recordings were analyzed according to localizing accuracy and frequency characteristics. The durations of discrete or regional ictal rhythms were also measured.

RESULTS

The percentage of discrete or regional EEGs was 23% in frontal lobe epilepsy, 52% in lateral temporal lobe epilepsy, 70% in occipital lobe epilepsy, and 10% in parietal lobe epilepsy. In order of frequency, the localizable ictal rhythms were theta, beta, alpha, delta, and rhythmic spike-and-wave. The duration of discrete or regional ictal rhythms was significantly shorter in frontal lobe epilepsy and parietal lobe epilepsy than in other epilepsies. Ictal beta activity was the most common rhythm in discrete-patterned EEGs. Structural lesions found on MRI did not significantly affect the localization of epileptogenic focuses in the patients. The type of seizure was not related to the degree of localization, with the exception of simple partial seizure.

CONCLUSIONS

Ictal surface EEG was clinically helpful in the localization of epileptogenic focuses in at least some neocortical epileptic syndromes.

Mutations in retinoid X receptor that impair heterodimerization with specific nuclear hormone receptor

Retinoid X receptor (RXR) serves as a promiscuous heterodimerization partner for many nuclear receptors through the identity box, a 40-amino acid subregion within the ligand binding domain. In this study, we randomly mutated two specific residues within the human RXRalpha identity box region previously identified as important determinants in heterodimerization (i.e. Ala(416) and Arg(421)). Interestingly, most of these mutants still retained wild type interactions with thyroid hormone receptor (TR), retinoic acid receptor, peroxisome proliferator-activated receptor alpha, small heterodimer partner, and constitutive androstane receptor. However, RXR-A416D and R421L were specifically impaired for interactions with TR, whereas RXR-A416K lost both TR and retinoic acid receptor interactions. Accordingly, RXR-A416D did not support T3 transactivation in mammalian cells, whereas RXR-A416K was not supportive of transactivation by retinoids or T3. These results provide a basis upon which to further design mutant RXRs highly selective in heterodimerization, potentially useful tools to probe nuclear receptor function in vivo.

A novel murine beta -defensin expressed in tongue, esophagus, and trachea

beta-Defensins are broad spectrum antimicrobial peptides expressed at epithelial surfaces. Two human beta-defensins, HBD-1 and HBD-2, have been identified. In the lung, HBD-2 is an inducible product of airway epithelia and may play a role in innate mucosal defenses. We recently characterized rat homologs (RBD-1, RBD-2) of the human genes and used these sequences to identify novel mouse genes. Mouse beta-defensin-4 (MBD-4) was amplified from lung cDNA using polymerase chain reaction primers designed from conserved sequences of RBD-2 and HBD-2. A full-length cDNA was cloned which encodes a putative peptide with the sequence MRIHYLLFTFLLVLLSPLAAFTQIINNPITCMTNGAICWGPCPTAFRQIGNCGHFKVRCCKIR. The peptide shares approximately 40% identity with HBD-2. MBD-4 mRNA was expressed in the esophagus, tongue, and trachea but not in any of 20 other tissues surveyed. Cloning of the genomic sequence of MBD-4 revealed two nearly (>99%) identical sequences encoding MBD-4 and the presence of numerous additional highly similar genomic sequences. Radiation hybrid mapping localized this gene to a region of chromosome 8 near several other defensins, MBD-2, MBD-3, and alpha-defensins (cryptdins)-3 and -17, consistent with a gene cluster. Our genomic cloning and mapping data suggest that there is a large beta-defensin gene family in mice. Identification of murine beta-defensins provides an opportunity to understand further the role of these peptides in host defense through animal model studies and the generation of beta-defensin-deficient animals by gene targeting.

Depletion of CD4 and CD8 T lymphocytes in mice in vivo enhances 1,25-dihydroxyvitamin D3-stimulated osteoclast-like cell formation in vitro by a mechanism that is dependent on prostaglandin synthesis

To investigate the role of T lymphocytes in osteoclastogenesis, we performed in vivo depletion of CD4 and/or CD8 T lymphocyte subsets and evaluated in vitro osteoclast-like cell (OCL) formation. T lymphocyte depletion (TLD) with mAbs was confirmed 24 h later by flow cytometry. OCL formation was stimulated with 1, 25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) in bone marrow and with recombinant mouse (rm) receptor activator of NF-kappaB ligand (RANK-L) and rmM-CSF in bone marrow and spleen cell cultures. OCL formation was up to 2-fold greater in 1,25-(OH)(2)D(3)-stimulated bone marrow cultures from TLD mice than in those from intact mice. In contrast, TLD did not alter OCL formation in bone marrow or spleen cell cultures that were stimulated with rmRANK-L and rmM-CSF. The effects of TLD seemed to be mediated by enhanced PG synthesis, because the PGE(2) concentration in the medium of 1, 25-(OH)(2)D(3)-stimulated bone marrow cultures from TLD mice was 5-fold higher than that in cultures from intact mice, and indomethacin treatment abolished the stimulatory effect of TLD on OCL formation. There was a 2-fold increase in RANK-L expression and an almost complete suppression of osteoprotegerin expression in 1, 25-(OH)(2)D(3)-stimulated bone marrow cultures from TLD mice compared with those from intact mice. Although there was a small (20%) increase in IL-1alpha expression in 1, 25-(OH)(2)D(3)-stimulated bone marrow cultures from TLD mice, TLD in mice lacking type I IL-1R and wild-type mice produced similar effects on OCL formation. Our data demonstrate that TLD up-regulates OCL formation in vitro by increasing PG production, which, in turn, produces reciprocal changes in RANK-L and osteoprotegerin expression. These results suggest that T lymphocytes influence osteoclastogenesis by altering bone marrow stromal cell function.

Ejaculatory duct obstruction: TRUS-guided opacification of seminal tracts

OBJECTIVE

To assess the usefulness of TRUS-guided aspiration and opacification of seminal tracts in the evaluation and management of patients with ejaculatory duct obstruction (EDO).

METHODS

In 21 men who had dilated seminal vesicles and/or midline cysts on TRUS, a mixture of contrast media and indigocarmine was injected and then pelvic radiographs were taken.

RESULTS

The diagnoses based on the findings of TRUS-guided opacification were bilateral EDO in 9 patients, unilateral EDO in 1, and midline cyst with EDO in 11. Midline cysts had communication with seminal tracts in 7. Transurethral unroofing was performed in 12, in all of whom blue color of the injected indigocarmine facilitated the surgical procedure.

CONCLUSION

TRUS-guided opacification of the seminal tracts with a mixture of contrast media and indigocarmine may be valuable in the evaluation and management of the patients with EDO.

Selection of cancer chemopreventive agents based on inhibition of topoisomerase II activity

The present study was undertaken to determine if in vitro inhibition of one or both of the two most dominant mammalian DNA topoisomerases (topos) is common among chemopreventive agents. To determine if an agent was a topo I inhibitor, we employed the DNA relaxation and nicking assays. For potential topo II inhibitors, we used the DNA unknotting and linearisation assays. 14 of 30 agents (47%) were ineffective in all four assays (IC(50) >100 microgram/ml), and 11 (37%) inhibited topo II catalytic activity. The sensitivity of the topo II assay was 63%, selectivity 93%, positive predictive value 91%, and total accuracy 77%. For chemopreventive efficacy, the positive predictive value of the unknotting assay was 92%, and the total accuracy was 60%. These data suggest that reduced topo II activity is a desirable property of many known chemopreventive agents. We conclude that the unknotting assay could be a valuable addition to the in vitro tests presently used to select chemopreventive agents.

Concurrent and sequential acquisition of different genital human papillomavirus types

Coinfection with multiple types of genital human papillomavirus (HPV) has been reported, but how frequently it occurs and whether prior infection with specific HPV types inhibits subsequent infection by related types are not known. To address this, 518 women were followed for an average of 2.9 years, and behavioral information and cervical and vulvovaginal swabs for HPV DNA assay were obtained at 4-month intervals. A polymerase chain reaction-based method was used to detect types frequently found in cervical cancers (HPV 16, 18, 31, and 45) and in genital warts (HPV 6 and 11). Concurrent acquisition of multiple types occurred more often than expected by chance. However, no 2 types were more or less likely to be acquired concurrently than any other 2 types. When considering sequential acquisition of HPV types, we found that risk of acquiring a new HPV type was not decreased among those with prior infection by a phylogenetically related or unrelated type (hazard ratio [95% confidence interval], 1.0 [0.4-3.0] and 1.3 [0.8-2.1], respectively).

Divergent effects of protein kinase C (PKC) inhibitors staurosporine and bisindolylmaleimide I (GF109203X) on bone resorption

Activation of protein kinase C (PKC) has been suggested to play a role in bone resorption. However, phorbol esters, which activate PKC, have been reported to have both stimulatory and inhibitory effects on bone resorption. To study the role of PKC in bone resorption further, we have measured calcium release elicited by bone-resorbing hormones from isolated bones incubated with the PKC inhibitors staurosporine (ST) and the more PKC-selective ST analog bisindolylmaleimide I (GF109203X; GF). In fetal rat limb bone organ cultures, ST (1 microM) or GF (1 microM) significantly reduced the bone resorption induced by maximal concentrations of parathyroid hormone (PTH). However, when submaximal concentrations of PTH were used, lower concentrations of the two antagonists had divergent effects. GF (20-300 nM) acted solely as an antagonist, whereas ST (10-100 nM) significantly enhanced resorptive responses to PTH. ST also enhanced the bone resorption elicited by alpha-thrombin, tumor necrosis factor-alpha (TNF-alpha), and thyroxin (T4). ST alone had small stimulatory effects in some experiments. GF prevented the stimulatory effects of ST alone as well as the enhancing effect of ST on PTH-stimulated resorption. The divergent effects of ST and GF on the responses of bone to low concentrations of PTH and the ability of GF to antagonize the stimulatory effects of ST suggest that PKC isozymes have complex and even antagonistic effects on bone resorption.