Climate-driven variability of the Southern Ocean CO2 sink.

The Southern Ocean is a major sink of atmospheric CO2, but the nature and magnitude of its variability remains uncertain and debated. Estimates based on observations suggest substantial variability that is not reproduced by process-based ocean models, with increasingly divergent estimates over the past decade. We examine potential constraints on the nature and magnitude of climate-driven variability of the Southern Ocean CO2 sink from observation-based air-sea O2 fluxes. On interannual time scales, the variability in the air-sea fluxes of CO2 and O2 estimated from observations is consistent across the two species and positively correlated with the variability simulated by ocean models. Our analysis suggests that variations in ocean ventilation related to the Southern Annular Mode are responsible for this interannual variability. On decadal time scales, the existence of significant variability in the air-sea CO2 flux estimated from observations also tends to be supported by observation-based estimates of O2 flux variability. However, the large decadal variability in air-sea CO2 flux is absent from ocean models. Our analysis suggests that issues in representing the balance between the thermal and non-thermal components of the CO2 sink and/or insufficient variability in mode water formation might contribute to the lack of decadal variability in the current generation of ocean models. This article is part of a discussion meeting issue 'Heat and carbon uptake in the Southern Ocean: the state of the art and future priorities'.

Modified Gant-Miwa-Thiersch procedure (mucosal plication with anal encircling) for rectal prolapse.

AIM: Rectal prolapse (RP) is usually associated with elderly women and is well recognized as having a detrimental effect on quality of life. A number of surgical procedures for RP are available, but morbidity and mortality are substantial. The Gant-Miwa-Thiersch procedure (GMT) has been frequently used for RP in Japan. However, as GMT has a high recurrence rate it is not widely used elsewhere. The aim of this study was to evaluate a modified version of GMT (mGMT) in comparison with other procedures. METHOD: mGMT was performed under spinal or local anaesthesia in 187 patients with RP. No normal mucosa was left between the tags and lateral wounds were created in the Thiersch procedure. Morbidity, mortality and recurrence rates were recorded. RESULTS: No serious postoperative complications and no operative deaths occurred after mGMT. Eight per cent of patients suffered from infection of the strings. The overall recurrence rate after mGMT was 7.5% with a median follow-up period of 13.8 years. CONCLUSION: On the basis of these results, we consider that mGMT has a number of advantages: it is minimally invasive, does not require general anaesthesia, is technically simple to perform and is associated with satisfactory outcomes and low morbidity. mGMT should be considered an option for the treatment of RP in elderly patients.

Modified open posterior internal sphincterotomy with sliding skin graft for chronic anal fissure and anal stenosis: Low recurrence rate and no serious faecal incontinence postoperative complication.

AIM: Lateral internal sphincterotomy (LIS) remains a standard for chronic anal fissure even though other surgical techniques have shown high efficacy. Faecal incontinence is a well-documented complication of LIS. We devised modified open posterior internal sphincterotomy (m-OPIS) with sliding skin graft (SSG), which is a combined procedure of OPIS and anal advancement flap. The aim of this study is to evaluate m-OPIS+SSG. METHODS: This was a retrospective, observational, single-arm study. m-OPIS+SSG was performed for chronic anal fissure and anal stenosis. m-OPIS involved incision of the internal sphincter muscle at the posterior midline until four fingers could be passed. The incision wound was closed by anastomosis of the anoderm and skin. Then, an arcuate skin incision was created and the skin graft was advanced into the anal canal. Follow-up was conducted by clinical consultation and telephone interview. Faecal continence was assessed by Cleveland Clinic Faecal Incontinence (CCFI) score. RESULTS: m-OPIS+SSG was performed in 143 patients. The mean patient age was 50±16 years. The success and overall recurrence rates after m-OPIS+SSG were 99% and 0.7%, respectively, with a median follow-up period of 16.3 years. One patient developed incontinence with liquid stools once during the 6-month period. None of the other patients suffered permanent faecal incontinence postoperatively. The postoperative CCFI score was 0.5±0.9. CONCLUSIONS: We consider m-OPIS+SSG as one of the efficacious options of procedure for chronic anal fissure and anal stenosis, owing to its high success rate, low recurrence rate and no postoperative complication of serious faecal incontinence.

Refined human artificial chromosome vectors for gene therapy and animal transgenesis.

Human artificial chromosomes (HACs) have several advantages as gene therapy vectors, including stable episomal maintenance, and the ability to carry large gene inserts. We previously developed HAC vectors from the normal human chromosomes using a chromosome engineering technique. However, endogenous genes were remained in these HACs, limiting their therapeutic applications. In this study, we refined a HAC vector without endogenous genes from human chromosome 21 in homologous recombination-proficient chicken DT40 cells. The HAC was physically characterized using a transformation-associated recombination (TAR) cloning strategy followed by sequencing of TAR-bacterial artificial chromosome clones. No endogenous genes were remained in the HAC. We demonstrated that any desired gene can be cloned into the HAC using the Cre-loxP system in Chinese hamster ovary cells, or a homologous recombination system in DT40 cells. The HAC can be efficiently transferred to other type of cells including mouse ES cells via microcell-mediated chromosome transfer. The transferred HAC was stably maintained in vitro and in vivo. Furthermore, tumor cells containing a HAC carrying the suicide gene, herpes simplex virus thymidine kinase (HSV-TK), were selectively killed by ganciclovir in vitro and in vivo. Thus, this novel HAC vector may be useful not only for gene and cell therapy, but also for animal transgenesis.

The cloning of PIG-A, a component in the early step of GPI-anchor biosynthesis.

The glycosylphosphatidylinositol (GPI) anchor is a membrane attachment structure of many proteins and occurs in a wide variety of eukaryotes from yeasts to mammals. The structure of the core of the GPI anchor is conserved in protozoa and mammals and so is its biosynthetic pathway. A complementary DNA encoding a human protein termed PIG-A (phosphatidylinositol glycan-class A) was cloned. PIG-A was necessary for synthesis of N-acetylglucosaminyl-phosphatidylinositol, the very early intermediate in GPI-anchor biosynthesis.

Use of sonographic elastography of the masseter muscles for optimizing massage pressure: a preliminary study.

To examine the stiffness of the masseter muscle using sonographic elastography and to investigate its relationship with the most comfortable massage pressure in the healthy volunteers. In 16 healthy volunteers (10 men and 6 women), the Masseter Stiffness Index (MSI) was measured using EUB-7000 real-time tissue elastography. They underwent massages at three kinds of pressures using the Oral Rehabilitation Robot (WAO-1). A subjective evaluation regarding the comfort of each massage was recorded on the visual analogue scale. Elastography was also performed in two patients with temporomandibular joint dysfunction with the myofascial pain. The mean MSI of the right and left muscles in the healthy volunteers were 0.85 +/- 0.44 and 0.74 +/- 0.35 respectively. There was no significant difference between the right and left MSI in the healthy volunteers. The MSI was related to massage pressure at which the healthy men felt most comfortable. The two temporomandibular disorder patients had a large laterality in the MSI. The MSI was related to the most comfortable massage pressure in the healthy men. The MSI can be one index for determining the massage pressure.

[Delayed surgery for traumatic rupture of the aortic arch with an isolated left vertebral artery; report of a case].

Although traumatic rupture of the thoracic aorta has been considered a surgical emergency, we report here an example of successful delayed surgery for acute traumatic rupture of the aortic arch with an isolated left vertebral artery in an 18-year-old woman. The patient was.admitted to the intensive care unit with hemothorax and, rib fractures, and a decision was made to treat the aortic injury conservatively until the patient was stabilized. She underwent surgery after 3 months of observation. After the isolated left vertebral artery had been anastomosed to the left carotid artery, total arch replacement was performed. Delayed surgery for aortic rupture as a treatment choice may be of benefit in selected cases of complex trauma.

Nitrite reductase gene upregulated during conidiation is involved in macroconidium formation in Fusarium oxysporum.

Fusarium oxysporum produces three kinds of asexual spores, microconidia, macroconidia, and chlamydospores. We previously found that the transcript level of the nitrite reductase gene of F. oxysporum, named FoNIIA, was markedly upregulated during conidiation compared with during vegetative growth. FoNIIA was also found to be positively regulated by Ren1 that is a transcription regulator controlling development of microconidia and macroconidia. In this study, we analyzed the function of FoNIIA in conidiation of F. oxysporum. Conidiation cultures showed markedly higher level of accumulation of FoNiiA protein as well as FoNIIA mRNA than vegetative growth cultures. FoNIIA protein was significantly decreased in cultures of the REN1 disruption mutant compared with that of the wild type. These results confirmed that FoNIIA expression is upregulated during conidiation and is positively regulated by REN1. The FoNIIA disruption mutants produced microconidia, macroconidia, and chlamydospores, which were morphologically indistinguishable from those of the wild type. The mutants, however, produced significantly fewer macroconidia than the wild type, although the wild type and mutant strains produced similar numbers of microconidia and chlamydospores. These results demonstrate that nitrite reductase is involved in quantitative control of macroconidium formation as well as nitrate utilization in F. oxysporum.

Involvement of beta 2-microglobulin modified with advanced glycation end products in the pathogenesis of hemodialysis-associated amyloidosis. Induction of human monocyte chemotaxis and macrophage secretion of tumor necrosis factor-alpha and interleukin-1.

beta 2-Microglobulin (beta 2M) is a major constituent of amyloid fibrils in hemodialysis-associated amyloidosis (HAA), a complication of long-term hemodialysis. However, the pathological role of beta 2M in HAA remains to be determined. Recently, we demonstrated that beta 2M in the amyloid deposits of HAA is modified with advanced glycation end products (AGEs) of the Maillard reaction. Since AGEs have been implicated in tissue damage associated with diabetic complications and aging, we investigated the possible involvement of AGE-modified beta 2M (AGE-beta 2M) in the pathogenesis of HAA. AGE- and normal-beta 2M were purified from urine of long-term hemodialysis patients. AGE-beta 2M enhanced directed migration (chemotaxis) and random cell migration (chemokinesis) of human monocytes in a dose-dependent manner. However, normal-beta 2M did not enhance any migratory activity. AGE-beta 2M, but not normal-beta 2M, increased the secretion of TNF-alpha and IL-1 beta from macrophages. Similar effects were also induced by in vitro prepared AGE-beta 2M (normal-beta 2M incubated with glucose in vitro for 30 d). When TNF-alpha or IL-1 beta was added to cultured human synovial cells in an amount equivalent to that secreted from macrophages in the presence of AGE-beta 2M, a significant increase in the synthesis of collagenase and morphological changes in cell shape were observed. These findings suggested that AGE-beta 2M, a major component in amyloid deposits, participates in the pathogenesis of HAA as foci where monocyte/macrophage accumulate and initiate an inflammatory response that leads to bone/joint destruction.

The receptor for advanced glycation end products (RAGE) is a central mediator of the interaction of AGE-beta2microglobulin with human mononuclear phagocytes via an oxidant-sensitive pathway. Implications for the pathogenesis of dialysis-related amyloidosis.

An important component of amyloid fibrils in dialysis-related amyloidosis is a form of beta2microglobulin modified with advanced glycation end products (AGEs) of the Maillard reaction, known as AGE-beta2M. We demonstrate here that the interaction of AGE-beta2M with mononuclear phagocytes (MPs), cells important in the pathogenesis of the inflammatory arthropathy of dialysis-related amyloidosis, is mediated by the receptor for AGEs, or RAGE. 125I-AGE-beta2M bound to immobilized RAGE or to MPs in a specific, dose-dependent manner (Kd approximately 53.5 and approximately 81.6 nM, respectively), a process inhibited in the presence of RAGE blockade. AGE-beta2M-mediated monocyte chemotaxis was prevented by excess sRAGE or anti-RAGE IgG. Induction of tumor necrosis factor-alpha (TNF) expression by MPs exposed to AGE-beta2M resulted from engagement of RAGE, as appearances of TNF transcripts and TNF antigen release into culture supernatants were prevented by addition of sRAGE, a process mediated, at least in part, by oxidant stress. AGE-beta2M reduced cytochrome c and the elaboration of TNF by MPs was inhibited by N-acetylcysteine. Consistent with these data, immunohistochemical studies of AGE-laden amyloid deposits of a long-term hemodialysis patient revealed positive staining for RAGE in the MPs infiltrating these lesions. These data indicate that RAGE is a central binding site for AGEs formed in vivo and suggest that AGE-beta2M-MP-RAGE interaction likely contributes to the initiation of an inflammatory response in amyloid deposits of long-term hemodialysis patients, a process which may ultimately lead to bone and joint destruction.

beta 2-Microglobulin modified with advanced glycation end products is a major component of hemodialysis-associated amyloidosis.

beta 2-Microglobulin (beta 2M) is a major constituent of amyloid fibrils in hemodialysis-associated amyloidosis, a complication of long-term hemodialysis patients. Amyloid fibril proteins were isolated from connective tissues forming carpal tunnels in hemodialysis patients with carpal tunnel syndrome. Two-dimensional polyacrylamide gel electrophoresis and Western blotting demonstrated that most of the beta 2M forming amyloid fibrils exhibited a more acidic pI value than normal beta 2M. This acidic beta 2M was also found in a small fraction of beta 2M in sera and urine from these patients, whereas heterogeneity was not observed in healthy individuals. We purified acidic and normal beta 2M from the urine of long-term hemodialysis patients and compared their physicochemical and immunochemical properties. Acidic beta 2M, but not normal beta 2M, was brown in color and fluoresced, both of which are characteristics of advanced glycation end products (AGEs) of the Maillard reaction. Immunochemical studies showed that acidic beta 2M reacted with anti-AGE antibody and also with an antibody against an Amadori product, an early product of the Maillard reaction, but normal beta 2M did not react with either antibody. Incubating normal beta 2M with glucose in vitro resulted in a shift to a more acidic pI, generation of fluorescence, and immunoreactivity to the anti-AGE antibody. The beta 2M forming amyloid fibrils also reacted with anti-AGE antibody. These data provided evidence that AGE-modified beta 2M is a dominant constituent of the amyloid deposits in hemodialysis-associated amyloidosis.

Real-time monitoring of in vitro transcriptional RNA synthesis using fluorescence resonance energy transfer.

We have developed a novel method for real-time monitoring of RNA synthesis in in vitro transcription reactions using fluorescence resonance energy transfer (FRET). Two 15mer DNAs, either of which was labeled with Bodipy493/503 as a donor or Cy5 as an acceptor, were prepared. When the two fluorescent DNAs hybridized to adjacent locations on Xenopus: elongation factor 1-alpha (xelf1-alpha) RNA, the distance between the two fluorophores became very close, causing FRET to occur and resulting in changes in fluorescence spectra. A high accessibility 30mer site of xelf1-alpha RNA was found and excess amounts of a pair of donor and acceptor DNA probes that were complementary to the site were added to the in vitro transcription reaction solution. Changes in fluorescence spectra were observed in response to progression of xelf1-alpha RNA synthesis that showed that the fluorescent probes hybridized to the synthesized RNA. Furthermore, when probes hybridizing to the synthesized xelf1-alpha RNA with less efficiency were used to monitor the reaction, spectral changes in response to RNA synthesis were also observed. This result suggests that the probes hybridized to synthesizing RNA molecules before they folded to form secondary structure and that there is no need to select sites on the RNA for the probes, which is required for probes hybridizing to folded RNA molecules.

[Extracardiac rupture of aneurysm of the noncoronary sinus of valsalva: report of a case].

A 78-year-old female was admitted to our hospital because of sudden onset of chest pain and general fatigue. A chest X-ray showed marked cardiomegaly and computed tomography (CT) revealed pericardial effusion with left pleural effusion. Upon admission to CCU, she suddenly lost consciousness and was intubated. Echocardiography confirmed increase in the amount of the pericardial effusion, which was drained at CCU. By an emergent operation, ruptured aneurysm of the noncoronary sinus of Valsalva to the pericardial space was confirmed upon opening the chest and patch plasty of the sinus of Valsalva was performed. The postoperative course was uneventful, and she was discharged on the 24th postoperative day. Extracardiac rupture of aneurysm of the sinus of Valsalva is extremely rare, and the emergent operation is indispensable.

Interplanar coupling-dependent magnetoresistivity in high-purity layered metals.

The magnetic field-induced changes in the conductivity of metals are the subject of intense interest, both for revealing new phenomena and as a valuable tool for determining their Fermi surface. Here we report a hitherto unobserved magnetoresistive effect in ultra-clean layered metals, namely a negative longitudinal magnetoresistance that is capable of overcoming their very pronounced orbital one. This effect is correlated with the interlayer coupling disappearing for fields applied along the so-called Yamaji angles where the interlayer coupling vanishes. Therefore, it is intrinsically associated with the Fermi points in the field-induced quasi-one-dimensional electronic dispersion, implying that it results from the axial anomaly among these Fermi points. In its original formulation, the anomaly is predicted to violate separate number conservation laws for left- and right-handed chiral (for example, Weyl) fermions. Its observation in PdCoO2, PtCoO2 and Sr2RuO4 suggests that the anomaly affects the transport of clean conductors, in particular near the quantum limit.

Quantification analysis of 5'-splice signal sequences in mRNA precursors. Mutations in rabbit beta-globin gene.

Concerning the signals which direct excision of introns from mRNA precursors in genes of higher eukaryotes, a consensus sequence composed of nine nucleotides, CAAG/GTAGAGT, has been proposed for the 5'-splice site, but actual 5'-splice site sequences differ from it to a greater or lesser degree. In the present paper, the 5'-splice site sequence of the rabbit beta-globin gene was analyzed using a quantification method (categorical discriminant analysis). In this method, each 9-nucleotide sequence in the pre-mRNA was characterized by its sample score, which shows the extent to which the sequence contains the signal. This approach could explain not only the location of the 5'-splice site, but also the experimental results of various point mutations in the 5'-splice region, as reported by Aebi et al. Our method further predicted the positions of cryptic 5'-splice sites, which are activated when the authentic 5'-splice site is abolished.

Transdermal drug delivery using ultrasound-theory, understanding and critical analysis.

This review focuses on a unique transdermal drug delivery enhanced by the action of ultrasound, referred as sonophoresis. Sonophoresis is an active form of transdermal delivery which enhances the transport of permeants, such as drugs through cell membranes as a result of ultrasonic energy. Ultrasonic sound waves cause acoustic cavitation, the resultant effects of which microscopically disrupt the lipid bilayers of the stratum corneum and thereby influencing the influx of permeants. Sonophoresis increases the penetration of various low molecular weight drugs as well as high molecular weight proteins. The objective of this review is to account the role of ultrasound parameters and the associated cavitational effects, gained through a number of investigations, in order to facilitate the understanding of this method.

Spatial study on a multibubble system for sonochemistry by laser-light scattering.

Volumetric oscillation of multiple cavitation bubbles in an ultrasonic standing-wave field is investigated spatially through the intensity measurements of scattered light from bubbles changing the measuring position in the direction of sound propagation. When a thin light sheet finer than half of wavelength of sound is introduced into the cavitation bubbles, at an antinode of sound pressure the scattered light intensity oscillates. The peak-to-peak light intensity corresponds to the number of the bubbles which contribute to the sonochemical reaction because the radius for oscillating bubbles at pressure antinodes is restrictive in a certain range due to the shape instability and the action of Bjerknes force that expels from the antinode bubbles that are larger than the resonant size. The experimental results show that the intensity waveform of oscillating scattered light measured at the side near the sound source is similar to the waveform as seen in a single-bubble experiment. The peak-to-peak light intensity for the scattered light waveform is low at the side near the sound source where the progressive wave is dominant, while at the side near the water surface far from the sound source the intensity is relatively high and has periodic structure corresponding to the periodicity of half wavelength from the standing wave. These tendencies of high intensity near the water surface and the periodicity correspond to the periodic luminescent stripes seen in images of luminescence in an ultrasonic standing wave as reported by Hatanaka et al. [Jpn. J. Appl. Phys. 39 (2000) 2962]. The present method of light scattering is promising for evaluating spatial distribution of violently oscillating cavitation bubbles which effect sonochemical reactions.

Stabilization, partial purification, and characterization of thyrotropin receptors in solubilized guinea pig fat cell membranes.

Specimens obtained during the course of efforts to purify the TSH receptor in guinea pig fat cell membranes solubilized with Triton X-100 displayed extensive loss of TSH binding activity, analogous to that seen by others during the purification of the TSH receptor in thyroid membranes. Therefore, as a preliminary to efforts to purify the TSH receptor in solubilized fat cell membranes (SFCM), experiments were undertaken to ascertain the factors responsible for this loss of binding activity and to find means for its prevention. Temperature proved to be the most important variable. SFCM stored at -70 C retained their activity with respect to the binding of bovine TSH (bTSH) for months, but binding activity was rapidly lost during storage of SFCM at 4 C, a loss due to a decrease in receptor number rather than binding affinity. Loss of binding activity during storage of SFCM at 4 C was unaffected by the addition of 1 mM cystine and was only slightly and temporarily retarded by a mixture of three protease inhibitors (phenylmethylsulfonyl fluoride, aprotinin, and leupeptin). These results indicated that loss of TSH receptors during storage at 4 C is not due to reduction of disulfide bonds or to proteolytic degradation. On the other hand, activity of the receptor was largely or entirely preserved during at least a week of storage at 4 C by the formation of a TSH-TSH receptor complex, by the addition of 40-50% glycerol either during solubilization or immediately thereafter, or by lyophilization immediately after solubilization. Receptors preserved by these three measures retained their original affinity for bTSH and their response to the TSH binding inhibitory activity of Graves'-immunoglobulin G. In the light of these results, SFCM were prepared in 40% glycerol and then subjected to TSH-affinity gel chromatography. The resulting materials contained at least 29.3% of the original binding activity, and their specific TSH binding activity was increased 227-fold. Saturation analysis of [125I]bTSH binding to this preparation revealed an association constant (Ka) (2.2 x 10(9) M-1), very similar to that in the original SFCM preparation. Binding of [125I]bTSH was inhibited in a dose-dependent manner by Graves'-immunoglobulin G, and in multiple preparations of the latter, TSH binding inhibitory activity measured in the affinity-purified receptor preparation was closely correlated with that measured in SFCM.(ABSTRACT TRUNCATED AT 400 WORDS)

Mechanisms of cerebral arterial relaxations to hydrogen peroxide.

BACKGROUND AND PURPOSE: The role of hydrogen peroxide in the regulation of cerebral arterial tone is not completely understood. Previous studies have demonstrated that hydrogen peroxide causes vasodilation of small cerebral arteries. The present study was designed to determine the mechanisms responsible for relaxations of large cerebral arteries to hydrogen peroxide. METHODS: Rings of canine middle cerebral arteries without endothelium were suspended for isometric force recording in modified Krebs-Ringer bicarbonate solution bubbled with 94% O(2)/6% CO(2) (37 degrees C, pH 7.4). Radioimmunoassay technique was used to determine the levels of cAMP and cGMP. RESULTS: During contraction to UTP (3 x 10(-6) or 10(-5) mol/L), hydrogen peroxide (10(-6) to 10(-4) mol/L) caused concentration-dependent relaxations. Catalase (1200 U/mL) abolished the relaxations to hydrogen peroxide. Inhibition of cyclooxygenase by indomethacin (10(-5) mol/L) significantly reduced relaxations to hydrogen peroxide. In arteries contracted by KCl (20 mmol/L), the relaxations to hydrogen peroxide were significantly reduced. In the presence of a nonselective potassium channel inhibitor, BaCl(2) (10(-4) mol/L), a delayed rectifier potassium channel inhibitor, 4-aminopyridine (10(-3) mol/L), or a calcium-activated potassium channel inhibitor, charybdotoxin (3 x 10(-8) mol/L), the relaxations to hydrogen peroxide were also significantly reduced. An ATP-sensitive potassium channel inhibitor, glyburide (5 x 10(-6) mol/L), did not affect the relaxations to hydrogen peroxide. Hydrogen peroxide produced concentration-dependent increase in levels of cAMP. Indomethacin (10(-5) mol/L) inhibited the stimulatory effect of hydrogen peroxide on cAMP production. In contrast, hydrogen peroxide did not affect the levels of cGMP. CONCLUSIONS: These results suggest that hydrogen peroxide may cause relaxations of large cerebral arteries in part by activation of arachidonic acid metabolism via cyclooxygenase pathway with subsequent increase in cAMP levels and activation of potassium channels.

Inhibition of thyrotropin-stimulated iodide uptake in FRTL-5 thyroid cells by crude immunoglobulin fractions from patients with goitrous and atrophic autoimmune thyroiditis.

We studied the effects of crude immunoglobulin (Ig) fractions of serum from patients with goitrous and atrophic autoimmune thyroiditis on TSH-, thyroid-stimulating immunoglobulin (TSI)-, forskolin-, and dibutyryl cAMP-stimulated 125I uptake by FRTL-5 thyroid cells. TSH-stimulated 125I uptake was inhibited by the Ig fractions from 15 patients with atrophic thyroiditis who had serum TSH binding inhibitor Igs (TBII), 10 (62.5%) of 16 TBII-negative patients with atrophic thyroiditis, 7 (43.8%) of 16 hypothyroid patients with goitrous thyroiditis who had no TBII activity, and only 2 (15.4%) of 13 euthyroid patients with goitrous thyroiditis who were negative for TBII. The mean inhibition of TSH-stimulated 125I uptake produced by the crude Igs from the former 3 groups of hypothyroid patients was statistically significant (P less than 0.001, P less than 0.001, and P less than 0.01, respectively) and correlated closely with the ability of the Ig fractions to inhibit TSI-stimulated 125I uptake (r = 0.882) and TSH-stimulated cAMP accumulation (r = 0.929). The inhibition of TSH- or TSI-stimulated 125I uptake by Ig samples containing TBII correlated significantly with the TBII activities. On the other hand, in the presence of Igs from TBII-negative hypothyroid patients, the inhibition of TSH-stimulated 125I uptake correlated significantly with that of forskolin-stimulated 125I uptake (r = 0.685). Although 6 (12.8%) of 47 Ig samples from hypothyroid patients inhibited dibutyryl cAMP-stimulated 125I uptake, the activities were marginal. These findings suggest that at least 2 types of antibodies are involved in the inhibition of TSH- or TSI-stimulated 125I uptake: 1 being a competitive inhibitor of TSH binding to its receptors, and another exerting influence on a step subsequent to TSH or TSI binding, presumably through adenylate cyclase inhibition.