Thyroid hormone and the cardiovascular system

Thyroid hormone is an important regulator of cardiac function and cardiovascular hemodynamics. Triiodothyronine, (T(3)), the physiologically active form of thyroid hormone, binds to nuclear receptor proteins and mediates the expression of several important cardiac genes, inducing transcription of the positively regulated genes including alpha-myosin heavy chain (MHC) and the sarcoplasmic reticulum calcium ATPase. Negatively regulated genes include beta-MHC and phospholamban, which are down regulated in the presence of normal serum levels of thyroid hormone. T(3) mediated effects on the systemic vasculature include relaxation of vascular smooth muscle resulting in decreased arterial resistance and diastolic blood pressure. In hyperthyroidism, cardiac contractility and cardiac output are enhanced and systemic vascular resistance is decreased, while in hypothyroidism, the opposite is true. Patients with subclinical hypothyroidism manifest many of the same cardiovascular changes, but to a lesser degree than that which occurs in overt hypothyroidism. Cardiac disease states are sometimes associated with the low T(3) syndrome. The phenotype of the failing heart resembles that of the hypothyroid heart, both in cardiac physiology and in gene expression. Changes in serum T(3) levels in patients with chronic congestive heart failure are caused by alterations in thyroid hormone metabolism suggesting that patients may benefit from T(3) replacement in this setting.

FDG PET imaging in hereditary thyroid cancer

AIM

To report the role of different imaging methods in staging individuals with multiple endocrine neoplasia 2A (MEN2A) or familial medullary thyroid carcinoma (FMTC).

MATERIAL AND METHODS

Fourteen newly diagnosed gene carriers underwent cervical ultrasound scanning (US), cervical and mediastinal CT, MRI and whole-body meta-[131I]iodobenzylguanidine (MIBG) scintigraphy and [18F]fluorodeoxyglucose (FDG) PET scanning.

RESULTS

US identified seven true primary cancer. CT and MRI located only tumors > or =5 mm in diameter. MIBG scintigraphy and FDG PET could not identify MTC foci within the thyroid. Whole-body FDG PET identified two true-positive and one false-positive lymph node metastases. MIBG scintigraphy did not identify lymph node metastases. Total thyroidectomy was performed in 12 cases, and subtotal thyroidectomy in two subjects.

CONCLUSIONS

Whole-body FDG PET and cervical US help stage individuals carrying mutant genes verifying MEN2A or FMTC.

Primary glomangioma of the liver: imaging findings

Glomus organs are small arteriovenous anastomoses that are chiefly responsible for thermoregulation of the distal portion of the extremities. Glomangiomas are benign tumors of these bodies. Glomangiomas occur preferentially in the fingers and toes, but some case reports have described primary glomangiomas in the respiratory or gastrointestinal tract and the genitals. To date, no glomangiomas of the liver have been observed. We report on a 61-year-old patient in whom routine ultrasound disclosed a subcapsular well-defined mass in the liver. On imaging studies, no correspondence to the usual liver tumors was found. Magnetic resonance-guided biopsy showed a primary glomangioma of the liver. Clinically, the patient had no appetite and lost weight over several months. Due to the patient's weight loss and potential malignant transformation, the tumor was excised. Histologic work-up confirmed the diagnosis of a glomangioma with no signs of malignancy.

Presentation of an unusual benign liver tumor: primary hepatic glomangioma

Glomus organs are small arteriovenous anastomoses chiefly responsible for thermoregulation of the distal portion of the extremities. Glomangiomas are benign tumors of these bodies. They occur preferentially in the fingers and toes, but some case reports describe primary glomangiomas in the respiratory or gastrointestinal tract and genitals. To date, no glomangiomas of the liver have been reported. We report on a 61-year-old patient in whom routine ultrasound disclosed a subcapsular well-defined mass in the liver. Further imaging showed that the mass did not correspond to any of the usual liver tumors. Biopsy finally revealed it to be a primary glomangioma of the liver. Clinically, there was lack of appetite and weight loss over a period of several months. Owing to the possibility of malignant transformation of glomangiomas, as described in the literature, the tumor was excised under existing clinical symptoms and continued slow growth. Further histological evaluation of the tumor did not reveal malignancy. Primary glomangioma of the liver is a new differential diagnosis for benign liver neoplasms. Because there is a potential for malignant transformation, the existence of clinical symptoms and continuing growth are indications for resection.

Human immunodeficiency virus type 1 subtype C molecular phylogeny: consensus sequence for an AIDS vaccine design?

An evolving dominance of human immunodeficiency virus type 1 subtype C (HIV-1C) in the AIDS epidemic has been associated with a high prevalence of HIV-1C infection in the southern African countries and with an expanding epidemic in India and China. Understanding the molecular phylogeny and genetic diversity of HIV-1C viruses may be important for the design and evaluation of an HIV vaccine for ultimate use in the developing world. In this study we analyzed the phylogenetic relationships (i) between 73 non-recombinant HIV-1C near-full-length genome sequences, including 51 isolates from Botswana; (ii) between HIV-1C consensus sequences that represent different geographic subsets; and (iii) between specific isolates and consensus sequences. Based on the phylogenetic analyses of 73 near-full-length genomes, 16 "lineages" (a term that is used hereafter for discussion purposes and does not imply taxonomic standing) were identified within HIV-1C. The lineages were supported by high bootstrap values in maximum-parsimony and neighbor-joining analyses and were confirmed by the maximum-likelihood method. The nucleotide diversity between the 73 HIV-1C isolates (mean value of 8.93%; range, 2.9 to 11.7%) was significantly higher than the diversity of the samples to the consensus sequence (mean value of 4.86%; range, 3.3 to 7.2%, P < 0.0001). The translated amino acid distances to the consensus sequence were significantly lower than distances between samples within all HIV-1C proteins. The consensus sequences of HIV-1C proteins accompanied by amino acid frequencies were presented (that of Gag is presented in this work; those of Pol, Vif, Vpr, Tat, Rev, Vpu, Env, and Nef are presented elsewhere [http://www.aids.harvard.edu/lab_research/concensus_sequence.htm]). Additionally, in the promoter region three NF-kappa B sites (GGGRNNYYCC) were identified within the consensus sequences of the entire set or any subset of HIV-1C isolates. This study suggests that the consensus sequence approach could overcome the high genetic diversity of HIV-1C and facilitate an AIDS vaccine design, particularly if the assumption that an HIV-1C antigen with a more extensive match to the circulating viruses is likely to be more efficacious is proven in efficacy trials.

[Primary glomangioma of the liver. A new differential benign liver tumor diagnosis]

Glomus organs are arteriovenous anastomoses which control the thermoregulation of the extremities. Benign tumors of these glomus organs, termed "glomangiomas", are therefore most frequently located in the fingers and toes. Case reports of primary glomangiomas in the respiratory- and gastrointestinal tracts as well as in the genital organs have been published. On the other hand, glomus tumors of the liver have not yet been described. We report the case of a 61-year-old patient with a smooth subcapsular lesion within the liver detected by a routine ultrasound scan. Further diagnostic imaging did not match with one of the common liver tumors. The diagnosis of a glomangioma was finally made by liver biopsy and subsequent histology. A review of the literature revealed a potential transformation of glomangiomas. Since the patient reported on inappetence weight loss and the tumor showed growth tendency, the indication for surgical excision was made. Final histologic investigation revealed no signs of malignancy. The primary glomangioma of the liver is a new differential diagnosis of benign liver tumors. As there is a possibility of malignant degeneration, we propose the decision for surgical removal once there are clinical symptoms and a growth tendency of the lesion.

Surgical management of prosthetic vascular graft infection: comparative retrospective analysis of 30 consecutive cases

BACKGROUND

Graft infection after vascular prosthetic reconstruction for the treatment of peripheral arterial occlusive disease (PAOD) is a rare but severe complication with poor outcome. The options for surgical treatment are not uniformly accepted and remain controversial.

PATIENTS AND METHODS

We retrospectively analyzed the histories of 30 patients treated for prosthetic graft infection (Szilagyi grade III) in our hospital between 1994 and 1999 to determine which forms of treatment were best suited for which types of patient. In the majority of cases the initial treatment was lower-extremity bypass surgery. The most frequent location of infection was the groin (73%). Staphylococci (13% of which were methicillin resistant) were the most common type of bacteria. The overall incidence of prosthetic infection was 2.3%.

RESULTS

After confirmation of the infection by computed tomography (CT) or white blood cell scintigraphy, one of the following 5 forms of surgical treatment was performed: 1. Removal of the infected prosthesis and its simultaneous replacement by an autologous vein bypass. 2. Bypass removal and secondary replacement by an autologous vein. 3. Extra-anatomical replacement. 4. Graft removal and primary amputation. 5. Local therapy with debridement and secondary wound healing. In some patients primary amputation after graft infection was necessary to prevent further deterioration with fulminant sepsis. The overall mortality was 17%, the amputation rate was 60%.

CONCLUSIONS

The best results were achieved by early complete removal of the alloplastic material and one-step replacement by either an autologous vein or extra-anatomic bypass. This resulted in a limb salvage rate of 54% and 40% and mortality rates of 9% and 0%, respectively.

Promoter I of the ovine acetyl-CoA carboxylase-alpha gene: an E-box motif at -114 in the proximal promoter binds upstream stimulatory factor (USF)-1 and USF-2 and acts as an insulin-response sequence in differentiating adipocytes

Acetyl-CoA carboxylase-alpha (ACC-alpha) plays a central role in co-ordinating de novo fatty acid synthesis in animal tissues. We have characterized the regulatory region of the ovine ACC-alpha gene. Three promoters, PI, PII and PIII, are dispersed throughout 50 kb of genomic DNA. Expression from PI is limited to adipose tissue and liver. Sequence comparison of the proximal promoters of ovine and mouse PIs demonstrates high nucleotide identity and that they are characterized by a TATA box at -29, C/EBP (CCAAT enhancer-binding protein)-binding motifs and multiple E-box motifs. A 4.3 kb ovine PI-luciferase reporter construct is insulin-responsive when transfected into differentiated ovine adipocytes, whereas when this construct is transfected into ovine preadipocytes and HepG2 cells the construct is inactive and is not inducible by insulin. By contrast, transfection of a construct corresponding to 132 bp of the proximal promoter linked to a luciferase reporter is active and inducible by insulin in all three cell systems. Insulin signalling to the -132 bp construct in differentiated ovine adipocytes involves, in part, an E-box motif at -114. Upstream stimulatory factor (USF)-1 and USF-2, but not sterol regulatory element-binding protein 1 (SREBP-1), are major components of protein complexes that bind this E-box motif. Activation of the 4.3 kb PI construct in differentiated ovine adipocytes is associated with endogenous expression of PI transcripts throughout differentiation; PI transcripts are not detectable by RNase-protection assay in ovine preadipocytes, HepG2 cells or 3T3-F442A adipocytes. These data indicate the presence of repressor motifs in PI that are required to be de-repressed during adipocyte differentiation to allow induction of the promoter by insulin.

Differential regulation of SR calcium transporters by thyroid hormone in rat atria and ventricles

Thyroid hormone exerts positive inotropic effects on the heart mediated in part by its regulation of calcium transporter proteins, including sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2), phospholamban (PLB), and Na(+)/Ca(2+) exchanger (NCX). To further understand the potential cardiac chamber-specific effects of thyroid hormone action, we compared the triiodo-L-thyronine (T(3)) responsiveness of calcium transporter proteins in atrial versus ventricular tissues. Rats were rendered hypothyroid by ingestion of propylthiouracil, and a subgroup of animals was treated with T(3) for 7 days (7 microg/day by constant infusion). Atrial and left ventricular (LV) tissue homogenates were analyzed for expression of SERCA2, PLB, and NCX proteins by Western blot analysis. SERCA2 protein significantly decreased by 50% in hypothyroid LV and was normalized by T(3) treatment. In contrast, SERCA2 protein in atria was unaltered in the hypothyroid state. PLB protein expression significantly increased by 1.6- and 5-fold in the hypothyroid LV and atria, respectively, and returned to euthyroid levels with T(3) treatment. Expression of NCX protein showed a greater response to T(3) treatment in atria tissue than in ventricular tissue. Sarcoplasmic reticulum calcium cycling is determined in part by the ratio of SERCA2 to PLB. This ratio was sixfold higher in the atria compared with LV, suggesting that PLB may play a minor role in the regulation of SERCA2 function in normal atria. We conclude that calcium transporter proteins are responsive to thyroid hormone in a chamber-specific manner, with atria showing a greater change in protein content in response to T(3). The differential effect on atria may account for the occurrence of atrial rather than ventricular arrhythmias in response to even mild degrees of thyrotoxicosis.

Identification of human immunodeficiency virus type 1 subtype C Gag-, Tat-, Rev-, and Nef-specific elispot-based cytotoxic T-lymphocyte responses for AIDS vaccine design

The most severe human immunodeficiency virus type 1 (HIV-1) epidemic is occurring in southern Africa. It is caused by HIV-1 subtype C (HIV-1C). In this study we present the identification and analysis of cumulative cytotoxic T-lymphocyte (CTL) responses in the southern African country of Botswana. CTLs were shown to be an important component of the immune response to control HIV-1 infection. The definition of optimal and dominant epitopes across the HIV-1C genome that are targeted by CTL is critical for vaccine design. The characteristics of the predominant virus that causes the HIV-1 epidemic in a certain geographic area and also the genetic background of the population, through the distribution of common HLA class I alleles, might impact dominant CTL responses in the vaccinee and in the general population. The enzyme-linked immunospot (Elispot) gamma interferon assay has recently been shown to be a reliable tool to map optimal CTL epitopes, correlating well with other methods, such as intracellular staining, tetramer staining, and the classical chromium release assay. Using Elispot with overlapping synthetic peptides across Gag, Tat, Rev, and Nef, we analyzed HIV-1C-specific CTL responses of HIV-1-infected blood donors. Profiles of cumulative Elispot-based CTL responses combined with diversity and sequence consensus data provide an additional characterization of immunodominant regions across the HIV-1C genome. Results of the study suggest that the construction of a poly-epitope subtype-specific HIV-1 vaccine that includes multiple copies of immunodominant CTL epitopes across the viral genome, derived from predominant HIV-1 viruses, might be a logical approach to the design of a vaccine against AIDS.

Transient activity in the human calcarine cortex during visual-mental imagery: an event-related fMRI study

Although it is largely accepted that visual-mental imagery and perception draw on many of the same neural structures, the existence and nature of neural processing in the primary visual cortex (or area V1) during visual imagery remains controversial. We tested two general hypotheses: The first was that V1 is activated only when images with many details are formed and used, and the second was that V1 is activated whenever images are formed, even if they are not necessarily used to perform a task. We used event-related functional magnetic resonance imaging (ER-fMRI) to detect and characterize the activity in the calcarine sulcus (which contains the primary visual cortex) during single instances of mental imagery. The results revealed reproducible transient activity in this area whenever participants generated or evaluated a mental image. This transient activity was strongly enhanced when participants evaluated characteristics of objects, whether or not details actually needed to be extracted from the image to perform the task. These results show that visual imagery processing commonly involves the earliest stages of the visual system.

Molecular genetic diagnostic program of multiple endocrine neoplasia type 2A and familial medullary thyroid carcinoma syndromes in Hungary

Medullary thyroid carcinoma (MTC) occurs usually in sporadic form, but about a quarter of the cases are hereditary and appear as part of one of the multiple endocrine neoplasia type 2 (MEN2) syndromes. Mutations in the RET protooncogene are known to be the cause of the MEN2A and familial medullary thyroid carcinoma (FMTC) syndromes in the majority of the families. Direct DNA testing allows prophylactic thyroidectomy to be offered to individuals carrying a mutation in the above codons, and in mutation-negative cases it reduces the yearly screening-related burden on family members at risk of the disease. By DNA sequencing and PCR-restriction fragment length polymorphisms, 65 MTC probands were examined for mutations in residues 609, 611, 618, 620 of exon 10, and in residues 634, 768, 804 of exons 11, 13, and 14 respectively of the RET protooncogene. In our study, mutations in the above codons were detected in all of the 14 clinically MEN2A and FMTC families. One of these mutations, TGC609 TCC has not been reported previously. Of the 14 probands with the mutation, 25 relatives also had the identified mutation and 18 relatives proved to be non-carriers. Among the 51 probands with clinically sporadic MTC, none was found to carry a mutation in the above positions even if indirect signs of MTC, pheochromocytoma or hyperparathyroidism could be detected in some families. The frequency of the TGC634AGC mutation is unexpectedly high in our samples, which can probably be attributed to a founder effect. We conclude that screening for mutations in these codons is effective in families fulfilling the strict clinical criteria of MEN2A or FMTC.

Effects of irrigation deprivation during the harvest period on yield determinants in mature almond trees

Effects of irrigation deprivation during the harvest period on yield determinants in mature almond (Prunus dulcis (Mill.) D.A. Webb cv. Nonpareil) trees were investigated during a 3-year field experiment. Return bloom and fruit set were measured on 2185 individually tagged spurs. Water stress resulting from irrigation deprivation during the harvest period, which purportedly coincides with the time of flower initiation, had no effect on the percentage of spurs that flowered or set fruit during subsequent years. Although water stress had no apparent effect on spur mortality, 66% of the tagged spurs died within 3 years. In addition, many spurs were vegetative by the third year, indicating the importance of spur renewal for sustained fruit production. Reductions in nut yield were evident after two successive years of irrigation deprivation during the harvest period. Regression analysis indicated a loss in yield of 7.7 kg tree(-1) in response to each 1 MPa decrease in stem water potential below -1.2 MPa during the previous seasons. The number of fruiting positions per tree (estimated indirectly for whole trees based on weight of current-year shoots > 5 cm in length) was negatively associated with water stress. Yield reduction in response to water stress during harvest appears to be a compound, multiyear effect, associated with reduced annual growth and renewal of fruiting positions.

Effects of irrigation deprivation during the harvest period on leaf persistence and function in mature almond trees

In nut tree orchards in California, irrigation is typically withheld during the harvest period to reduce the likelihood of bark damage during mechanical shaking of the trees. The ensuing water stress, however, may result in premature defoliation and subsequent yield declines. Our objective was to establish and quantify the water stress resulting from irrigation deprivation and determine its impact on leaf function and persistence in mature almond trees (Prunus dulcis (Mill.) D.A. Webb cv. Nonpareil) during a 3-year field experiment. The severity of the water stress was characterized by measurements of predawn leaf (Psi(pd)) and midday stem (Psi(ms)) water potentials, stomatal conductance (gs), net CO2 assimilation rate (A) and leaf abscission. During 1995, Psi(ms) of fully irrigated (FI) trees was maintained above -1.0 MPa. In trees in the moderate- (MS) and severe-stress (SS) treatments, Psi(ms) was reduced to -1.4 to -2.0 MPa and -2.0 to -2.6 MPa, respectively. After 18 days of irrigation deprivation, A was reduced by 32 and 58% at midday and early afternoon, respectively, compared with morning values. A significant decrease in morning values of A only occurred after 30 days of irrigation deprivation. Water-use efficiency and A declined as evaporative demand increased from morning to afternoon. Assimilation also declined seasonally as leaves aged. Midday stem water potential was highly correlated with A, but less so with gs. The coefficient of determination between Psi(ms) and gs improved considerably when vapor pressure deficit and wind were multiply regressed with Psi(ms). Although A recovered rapidly when MS trees were irrigated, recovery in SS trees was slower and incomplete. Integrating the MS and SS effects for an extended period during 1995 resulted in 14 and 30% declines in A, and 6 and 20% declines in gs, respectively. The apparent Psi(ms) threshold for leaf abscission was -1.8 MPa. Daily canopy light interception declined with decreasing Psi(ms) as a result of premature defoliation (and perhaps altered leaf angles) from 67.9% in FI trees to 61.4 and 60.7% in MS and SS trees, respectively.

Preserved contractile function despite atrophic remodeling in unloaded rat hearts

The present study was designed to determine whether myocardial atrophy is necessarily associated with changes in cardiac contractility. Myocardial unloading of normal hearts was produced via heterotopic transplantation in rats. Contractions of isolated myocytes (1.2 mM Ca2+; 37 degrees C) were assessed during field stimulation (0.5, 1.0, and 2.0 Hz), and papillary muscle contractions were assessed during direct stimulation (2.0 mM Ca2+; 37 degrees C; 0.5 Hz). Hemodynamic unloading was associated with a 41% decrease in median myocyte volume and proportional decreases in myocyte length and width. Nevertheless, atrophic myocytes had normal fractional shortening, time to peak contraction, and relaxation times. Despite decreases in absolute maximal force generation (F(max)), there were no differences in F(max)/ area in papillary muscles isolated from unloaded transplanted hearts. Therefore, atrophic remodeling after unloading is associated with intact contractile function in isolated myocytes and papillary muscles when contractile indexes are normalized to account for reductions in cell length and cross-sectional area, respectively. Nevertheless, in the absence of compensatory increases in contractile function, reductions in myocardial mass will lead to impaired overall work capacity.

[The interaction between saliva and cigarette smoke and its devastating biological effects as related to oral cancer]

Saliva is the first body fluid to confront inhaled cigarette smoke (CS) which is injurious to the oral cavity and is associated with several oral diseases and cancer. We have recently demonstrated in an In vitro model that an exposure of saliva to nine 'puffs' of CS induced a distinct increase in protein carbonyls. This elevation of protein carbonyls caused by CS may be the result of aldehydes presented in the CS reacting with sulphydryl (-SH) groups of the proteins. Moreover, following the exposure to CS, the activities of several salivary enzymes amylase, lactate dehydrogenase (LDH) and acid phosphatase (ACP) were found to be significantly reduced by 83%, 57% and 77%, respectively. However, CS had no effect on the activities of aspartate aminotransferase and alkaline phosphatase. In the current study we found that CS also reduced salivary peroxidase activity by no less than 80% which may be of a great importance to the clinical set up as peroxidase is considered a pivotal enzyme of the the salivary protecting system. Furthermore, in contrast to LDH findings in saliva, the LDH activity in plasma was not reduced following its exposure to CS.

CONCLUSION

Hence, we concluded that the loss of salivary enzyme activities may be due to various agents in the CS that affect the enzyme via different mechanisms.

Persistence of stable intragraft cell chimerism in rat liver allografts after drug-induced tolerance

BACKGROUND

Drug-induced tolerance of rat liver allografts is well documented. We analyzed cellular events during immunosuppressive therapy on day (d) 10 and in the late phase (d 100) after transplantation to assess for characteristics in the intrahepatic leukocyte (IHL) population in the phase of tolerance.

METHODS

Lewis rats served as recipients of Dark Agouti rat livers. Temporary immunosuppression with either cyclosporine (CsA) monotherapy (3 mg/kg/d) or triple therapy that consisted of a subtherapeutic CsA dosage (0.25 mg/kg/d) and monoclonal antibodies directed against the interleukin-2 receptor (IL-2R, CD25) and the intercellular adhesion molecule-1 (ICAM-1, CD54) was administered from postoperative d 0 to d 13. Cell migration and cell activation within liver grafts was assessed by standard histology and flow cytometry. IHL apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL).

RESULTS

Both CsA monotherapy and triple therapy prolonged liver allograft survival to more than 100 d and led to the induction of donor-specific tolerance. Untreated recipients rejected their allografts within 14 d. In both groups, donor-specific IHLs initially dropped to 18% to 25% on d 10, but they rebounded to as much as 40% on d 100 as a common characteristic of both groups. Within this population, donor-specific T cells were dominant. In both groups, increased numbers of activated (IL-2R+) CD8+ T lymphocytes were present on d 100. No accumulation of apoptotic IHL was observed on d 100. Their proportion was unchanged in the triple therapy group and slightly decreased in the CsA group compared to the syngeneic controls.

CONCLUSIONS

The present study reveals that tolerant liver allografts are repopulated by donor-specific T lymphocytes. This phenomenon is independent of the type of applied immunosuppression. The persistence of activated CD8+ T cells in the phase of proven donor-specific tolerance on d 100 indicates that liver tolerance is associated with the state of a permanent intragraft immune activation. It seems that the coexistence of donor cells with infiltrating recipient cells within liver grafts, termed intrahepatic cell chimerism, is characteristic for tolerated liver allografts.

Analysis of cellular events in hepatic allografts: donor progenitors induce intragraft chimerism

Long-term graft acceptance and tolerance induction after allogeneic rat liver transplantation are well described. However, the underlying mechanisms remain unclear. In this study we investigated the cellular events within the liver graft during initial immunosuppression and long-term acceptance. Orthotopic liver transplantation was performed in the Dark Agouti (DA)-to-Lewis (LEW) and LEW-to-DA rat strain combination. In order to achieve long-term acceptance, LEW recipients of DA livers were treated with two different short-term therapies. Non-parenchymal cells (NPC) were isolated from liver allografts on days + 10 and + 100 after transplantation and donor-specific leukocytes were immunophenotyped by flow cytometry. Both the monotherapy and triple therapy prolonged graft survival (> 100 days). Liver allografts from LEW donors into DA recipients were spontaneously accepted across a complete MHC mismatch without immunosuppression. Liver allograft rejection was induced by infiltrating alloreactive immunocompetent cells. But the intensities of cell infiltration in the early and late phases after transplantation did not correlate with eventual outcome. Donor-specific NPC decreased to 18-25% on day + 10 in both therapeutic groups, but had rebounded to up to 40% by day + 100. Recurrence of donor-specific cells was caused almost exclusively by rising T cell counts. The persistence of dendritic cells in the late phase after transplantation could be clearly demonstrated. Repopulation by donor-specific T lymphocytes was observed in long-term accepted liver grafts. This recurrence may be based on the differentiation of liver-derived progenitor cells. The persistent coexistence of donor and recipient cells within the liver allograft (intrahepatic chimerism) appears to be characteristic and may be important for long-term acceptance.

Clinical, metabolic, and organ-specific indices of thyroid function

Presently there are a sufficient number of sensitive and specific tests of thyroid function to establish a diagnosis of thyroid disease with a high degree of precision. A variety of clinical situations, however, including but not limited to thyroid hormone resistance states, alterations in thyroid-binding proteins and nonthyroidal illness, challenge the clinician to evaluate the thyroid status of the patient beyond that which can be done with routine laboratory tests. This article reviews several clinical, cardiac, skeletal muscle, and other laboratory studies that have been suggested to complement the overall assessment of thyroid status.

A haemophilia A and B molecular genetic diagnostic programme in Hungary: a highly informative and cost-effective strategy

Our aim was to set up a protocol in order to provide carrier and prenatal diagnosis to Hungarian haemophilia A (HA) and B (HB) patients and their relatives. For HA, a combination of direct mutation detection and some indirect marker analyses were used: the detection of the inversion mutation and analysis of three polymorphisms, BclI, IVS13 (CA)n and P39(CA)n. In severe cases, direct mutation detection was performed first. In inversion-negative severe cases and in moderate and mild cases, indirect methods were used. For carrier and prenatal diagnosis in HB, four polymorphisms, DdeI, TaqI, XmnI, and HhaI were examined. Our DNA bank contains samples from 50 HA families (34 severe, 15 moderate and one mild) and seven HB families from different parts of the country. In 100% of the HA cases either the gene inversion and/or at least one of the polymorphisms was found to be informative for carrier or prenatal diagnosis. In the HB cases, an informative marker was found in 95% of the cases (19 of 20). We conclude that these strategies are sufficient to make genetic diagnosis available to almost all HA and HB families in the region. This approach is highly informative and cost-effective, so it can be very useful in countries where direct sequencing of genes for factor VIII and IX is not available for routine diagnosis.

New insights into salivary lactate dehydrogenase of human subjects

Lactate dehydrogenase (LDH) is a ubiquitous enzyme that plays a significant role in the clinical diagnosis of pathologic processes. The purpose of the current study was to examine LDH activity and isoenzyme profile of whole saliva and to compare it with the LDH activity of salivary glands and plasma before and after exposure to cigarette smoke (CS). The range of LDH activity in whole saliva at rest was 360 to 430 U/L. The mean +/- SEM of LDH activity in parotid and submandibular/sublingual salivary secretions was 41.3 +/- 19.2 U/L and 77.5 +/- 30.4 U/L, respectively, which implied that 75% of the whole-saliva LDH originated from an extra-salivary gland source. The profile of salivary LDH isoenzymes was found to have an entirely different pattern from that found in plasma, similar to that found in oral epithelium, indicating that the major source of salivary LDH is probably the oral epithelium-shedding cells. Therefore, salivary LDH may be evaluated for possible oral mucosal pathologies in a manner similar to that used for evaluating other tissue pathologies--such as those in heart, muscle, or liver--that can be detected in plasma. Exposure of whole saliva to CS in vitro resulted in a 41% reduction in LDH activity. However, CS exposure had no effect on LDH activity in plasma. Whole saliva, in contrast to plasma, contains redox-active metal ions such as iron and copper that may enhance LDH loss of activity. Therefore we conclude that whole saliva in the presence of CS becomes a potent protein-modifying agent that can destroy some of its endogenous components.

Thyroid hormone increases pacemaker activity in rat neonatal atrial myocytes

The effects of thyroid hormone (3,3',5-triiodo- L -thyronine, T3) on pacemaker activity were studied with electrophysiological and pharmacological approaches using spontaneously beating neonatal atrial myocytes cultured from 2-day-old rats. Treatment with T3 (10(-8)m) for 24-48 h led to a positive chronotropic effect. The beating rate of T3-treated cells was 244+/-19 beats/min and for control cells it was 122+/-10 beats/min (P<0.05). Action potentials were recorded and showed that the predominant effect of T3 was to increase the diastolic depolarization rate (99.5+/-9.8 in T3-treated group v 44.0+/-7.8 mV/s in untreated group). Some cells that exhibited pacemaker activity lacked a pacemaker current (I(f)) under voltage clamp conditions I(f)was recorded in 5 of 12 spontaneously active control cells and in 6 of 10 T3-treated cells. In those cells exhibiting the pacemaker current, the I(f)density was significantly larger in T3-treated cells (-7.9+/-2.6 pA/pF v-1.8+/-0.5 pA/pF in control). The L-type Ca2+ current density was similar in the two groups (at -7 mV, -7.5+/-1.5 in treated group v-8.6+/-1.0 pA/pF in control). In the presence of T3, the Na+-Ca2+ exchanger current (I(Na/Ca)) density was larger (e.g. at +60 mV, it was 4.8+/-0.5 v 3.5+/-0.2 pA/pF in control cells, P<0.05). As intracellular Ca2+ is extruded from the cell, the electrogenic Na+-Ca2+ exchanger causes a declining inward current, which may contribute to the pacemaker potential-this declining inward current was demonstrated using the action potential voltage clamp technique and was shown to be larger in T3-treated myocytes. Our data demonstrate that thyroid hormone enhances pacemaker activity and that this may be due in part to an increased Na+-Ca2+ exchanger activity.