Tribonat--a comprehensive summary of its properties

OBJECTIVE

To review available investigations describing the properties of the buffer mixture Tribonat.

DATA SOURCES

Original reports published in peer-reviewed medical journals.

STUDY SELECTION

Review of 76 citations, including four original studies on the effect of Tribonat performed by or supervised by the author, and six original studies concerning Tribonat originating from the institution to which the author is affiliated.

DATA EXTRACTION

Computer search of the literature regarding treatment with alkaline buffers during cardiopulmonary resuscitation.

DATA SYNTHESIS

Routine buffering of acidosis has been questioned, but clinical situations still exist where such treatment is regarded as indicated. In such cases, a buffer with advantageous qualities and few side-effects is desirable. The hitherto commonly used buffers do not always fulfill these requirements, and a more profound knowledge of the alternative Tribonat may therefore be warranted.

CONCLUSIONS

The reviewed articles support the assumption that Tribonat may offer important advantages over previously used buffers in situations where administration of an alkalinizing agent is indicated.

Major histocompatibility complex class II expression and parathyroid autoantibodies in primary hyperparathyroidism

BACKGROUND

Autoimmune diseases are characterized by induced parenchymal expression of major histocompatibility complex (MHC) class II antigens and circulating autoantibodies directed toward surface structures on the target cells. MHC class II expressions can be modified by viral infections of potential pathogenic importance in autoimmune reactions. Primary hyperparathyroidism exhibits incompletely clarified cause.

METHODS

With cryosections, human parathyroid glands were stained with monoclonal antibodies to MHC class II antigens according to a peroxidase-antiperoxidase technique. Human parathyroid adenoma tissue transplanted to nude mice and rat parathyroid glands was tested with serum from patients with hyperparathyroidism and control subjects.

RESULTS

Induced MHC class II expression was demonstrated on parathyroid parenchymal cells in 13 of 54 adenomatous and eight of 23 hyperplastic glands of patients with primary hyperparathyroidism. This reactivity was absent in 12 normal glands, nine normal-sized glands associated with the adenomas, and 17 enlarged glands of patients with hyperparathyroidism caused by uremia. Staining of parathyroid tissue was found with serum from 27 of 38 patients with primary hyperparathyroidism, whereas this reactivity was absent on rat thyroid and pancreatic tissue, as well as with control sera.

CONCLUSION

The concurrent induction of MHC class II antigen expression and c circulating antiparathyroid autoantibodies in 16 or 38 patients with primary hyperparathyroidism suggests hitherto unrecognized immunologic involvement in this disease.

Alkaline buffers for correction of metabolic acidosis during cardiopulmonary resuscitation with focus on Tribonat--a review

A combined hypercarbic and metabolic acidosis develops during the low flow state of cardiac arrest treated with cardiopulmonary resuscitation. Several negative consequences of the acidosis have been demonstrated, two of the most important being reduced contractility of the ischaemic but still beating myocardium and impaired resuscitability of the arrested heart. Even though interventions to re-establish a spontaneous circulation should be the number one priority during cardiopulmonary resuscitation, attempts to treat the acidosis are often carried out in order to avoid the reported negative inotropic effect. Different alkaline buffers have been used, but it has been demonstrated over the years that such treatment may aggravate the situation due to a variety of deleterious side-effects of the buffers. A mixture of THAM, acetate, sodium bicarbonate and phosphate registered as Tribonat has been suggested as a suitable alternative to conventional buffer substances. The problems preceding the designation of Tribonat as well as studies evaluating its effects are reviewed in this article. Tribonat seems to offer a more well-balanced buffering without any major disadvantages compared with previously used alkaline buffers, even though improved survival has not been reported.

Propofol induces a lowering of free cytosolic calcium in myocardial cells

BACKGROUND

The intravenous anaesthetic drug propofol has been shown to depress myocardial contractility. Ketamine, on the other hand, is a well-documented cardiovascular stimulant. These differences could possibly be due to different effects of the drugs on the calcium homeostasis of the myocardium.

METHODS

The fluorescent intracellular probe fura-2 acetoxymethyl ester (fura-2/AM) was used in this in vitro investigation to study the influence of intravenous anaesthetic drugs on free cytosolic calcium concentration in suspensions of isolated rat myocardial cells.

RESULTS

Addition of 0.5-2.0 micrograms/mL propofol resulted in a significant and dose-dependent decrease of free cytosolic calcium concentration in the myocardial cells, while addition of 0.25-2.5 micrograms/mL ketamine did not affect this concentration significantly.

CONCLUSION

The results imply that the previously demonstrated negative inotropic effect of propofol could possibly be related to its influence on calcium availability in the myocardium.

Influence of alkaline buffers on cytoplasmic pH in myocardial cells exposed to hypoxia

The fluorescent intracellular probe 2',7'-bis-(carboxyethyl)-5,6-carboxyfluorescein acetoxymethyl ester was used in this experimental study to investigate the effects of different alkaline buffers on cytoplasmic pH in suspended myocardial cells under normal as well as hypoxic conditions. A dose-dependent intracellular acidification was achieved after addition of sodium bicarbonate or Tris buffer mixture (Tribonat) to the myocardial cells under normal conditions. After this immediate decrease in cytoplasmic pH, a tendency for the pH to rise again was recorded during the observation period, but this elevation of pH occurred to variable degrees with the different agents and dosages. Addition of larger volumes of Tribonat caused the cytoplasmic pH to return to the initial value during the observation time. Addition of Ringer's acetate produced a significant and persistent cytoplasmic acidification. Larger volumes of Carbicarb as well as pure trometamol (Tris) caused a lasting intracellular alkalinization. Hypoxia per se caused a marked intracellular acidosis in the cardiomyocytes. During hypoxia, addition of sodium bicarbonate caused a further decrease of cytoplasmic pH, turning into an increase during the observation period. Also, Tribonat caused an immediate further acidification, but 15 min after the addition the intracellular pH-value had reached the normal level of normoxic cells. Addition of Ringer's acetate caused a further significant and lasting decrease of intracellular pH. The effect of Carbicarb was a persistent alkalinization of the cell interior. Trometamol produced the most pronounced rise of cytoplasmic pH. In conclusion, this in vitro study shows that Tris buffer mixture (Tribonat) possesses important qualities for correction of metabolic acidosis due to hypoxia and may perhaps be preferred over other alkaline buffers in some situations.

Expression and function of a CD4-like molecule in parathyroid tissue

BACKGROUND

Parathyroid tissue expresses the T-lymphocyte antigens CD3 and CD4, and parathyroid CD3 has earlier been proposed to interact in the regulation of parathyroid hormone (PTH) release.

METHODS

Anti-Leu3a, a monoclonal antibody recognizing CD4, was used to stain parathyroid tissue immunohistochemically, to influence PTH secretion from enzymatically dispersed parathyroid cells, and to immunoprecipitate parathyroid CD4. Northern blot and polymerase chain reaction were used to clarify the similarity between parathyroid and lymphocytic CD4. Serum PTH level was measured with an immunoradiometric assay in healthy control subjects and individuals with human immunodeficiency virus type 1.

RESULTS

The parenchyma of normal and abnormal parathyroid tissue displayed strikingly variable CD4 expression. Immunoprecipitation showed a 56 kd molecule, and Northern blot and polymerase chain reaction confirmed the similarity with lymphocyte CD4. Anti-Leu3a inhibited preferentially low calcium-stimulated secretion of PTH from dispersed parathyroid cells, without discernible influences on the cytoplasmic calcium concentration of these cells. Individuals with human immunodeficiency virus type 1 displayed significantly lower serum PTH levels than healthy control subjects.

CONCLUSIONS

The results suggest that the human parathyroid chief cell expresses a CD4 moiety, which seems to interact in the PTH release in vitro and in vivo and which seems to use another second messenger system than the structurally similar T-cell equivalent.

Effect of tris buffer on free cytosolic calcium in myocardial cells

OBJECTIVE

To study the effect of tris buffer on free cytosolic calcium in vitro.

DESIGN

Open, randomized, control trial of dispersed rat myocardial cells.

SETTING

Experimental laboratory in a large university hospital.

SUBJECTS

Dispersed myocardial cells from Sprague-Dawley rats.

INTERVENTIONS

The influences of pure trometamol (tris) and a tris butter mixture, as well as conventional sodium bicarbonate on free cytosolic calcium in suspended rat myocardial cells were studied with the fluorescent intracellular probe fura-2.

MEASUREMENTS AND MAIN RESULTS

Addition of pure trometamol (tris) resulted in a significant increase of free cytosolic calcium in myocardial cells suspended in a buffer containing 1.25 mM of ionized calcium. The actions of trometamol display a dose-dependency in relation to the concentration of external ionized calcium since the ionized calcium response was reduced in a buffer with 0.5 mM of extracellular ionized calcium. Furthermore, removal of external ionized calcium totally prevented trometamol induced increases of ionized calcium, indicating that this increase is dependent on transmembrane ionized calcium fluxes. When tris buffer mixture was investigated in 1.25 mM of calcium, as well as 0.5 mM of external ionized calcium, a decrease of ionized calcium was noted initially, followed by an increase during the observation period. Addition of sodium bicarbonate to the two experimental settings resulted in a more prominent initial decrease of ionized calcium, followed by a slower increase which did not reach the initial values during the 20-min observation period. Extracellular pH was also included as a variable. When the cells were suspended in a buffer containing 1.25 mM of ionized calcium with a pH of 6.80 instead of 7.40 (as above), addition of pure trometamol also resulted in an increase of ionized calcium; however, after 20 mins this increase was smaller as compared with the results above. When tris buffer mixture as well as sodium bicarbonate was added, initial decreases of ionized calcium were recorded, followed by smaller increases during the observation period, compared with the increase in buffers with a pH of 7.40.

CONCLUSIONS

Pure trometamol (tris) induces an increase in free cytosolic calcium in suspended myocardial cells.

Influence of alkaline buffers on cytoplasmic pH in myocardial cells exposed to metabolic acidosis

The influence of different clinically used alkaline buffers on cytoplasmic pH in normal as well as acidotic rat myocardial cells was investigated in this study by means of the fluorescent intracellular probe 2',7'-bis-(carboxyethyl)-5,6-carboxyfluorescein acetoxymethyl ester (BCECF-AM). It was shown that both sodium bicarbonate and Tris buffer mixture (Tribonat) caused a significant and dose-dependent acidification of the cytoplasm of suspended myocardial cells with normal initial intracellular pH. This decrease was followed by a slow increase during the observation period. The initial cytoplasmic pH value was more easily reached when Tris buffer mixture was used. Ringer's acetate also caused a decrease of intracellular pH, but this change persisted and was further amplified during the experiment. Carbicarb in larger dosages as well as pure trometamol (Tris) caused a pronounced dose-dependent and lasting intracellular alkalinization. Intracellular acidosis was achieved by preincubating the cells in sodium acetate. Addition of sodium bicarbonate caused an initial and dose-dependent acidification of the cytoplasm followed by a slow increase to values slightly above the induced acidosis. In contrast, Tris buffer mixture showed a tendency towards an initial acidification only when larger dosages were used, and correction of the induced acidosis was possible by use of moderate to large volumes. Ringer's acetate produced a lasting and dose-dependent decrease of cytoplasmic pH, while Carbicarb and pure trometamol caused an immediate, pronounced and persistent alkalinization. Myocardial cells with low initial cytoplasmic pH due to preincubation in an acid buffer also showed an early decrease of intracellular pH after addition of sodium bicarbonate and Tris buffer mixture. In the case of sodium bicarbonate correction of the acid-base disturbance was not achieved during the observation period, while this was accomplished by use of larger volumes of Tris buffer mixture. Carbicarb in larger volumes caused an increase in intracellular pH. The most significant and persistent increases of cytoplasmic pH was achieved by use of pure trometamol. In conclusion, the present in vitro study implies that Tris buffer mixture (Tribonat) is well-suited for correction of intracellular acidosis since it acts without causing a pronounced initial intracellular acidosis or a later potentially hazardous huge cytoplasmic alkalinization.

Scintigraphy and biodistribution of monoclonal adrenocortical antibody in mice grafted with human adrenocortical carcinoma

BACKGROUND

A murine monoclonal antibody recognizing normal and neoplastic human adrenocortical cells has been evaluated for scintigraphic localization and biodistribution in 53 nude mice grafted subcutaneously with human adrenocortical cell lines SW-13 and T-CAR 1.

METHODS

The immunoglobulin G1 antibody and its Fab'2 fragment were purified and labeled with 125I. The tumor grafts exhibited diameters of 5 to 15 mm at 4 to 6 weeks after transplantation, when mice received a single subcutaneous or intraperitoneal injection of 50 micrograms iodinated intact or fragmented antibody, respectively.

RESULTS

Examination up to 8 days after immunoglobulin G administration showed mean radioactivity ratios less than 1.0 for tumor to blood and corresponding ratios in tumor to lung, liver, spleen, and kidney from 0.6 to 5.3 at the time of peak tumor to blood ratio. A high background activity was noted on scintigraphic tumor visualization with the iodinated immunoglobulin G. In contrast, the radiolabeled Fab'2 fragment displayed gradually rising tumor to blood ratios, which, 4 days after injection, averaged 10.5 for T-CAR1 and 5.3 for SW-13. Tumor transplants were scintigraphically visualized without substantial background activity 3 days after Fab'2 injection, when the ratio of radioactivity in the tumor to the investigated murine organs was 0.5 to 7.3.

CONCLUSIONS

The findings substantiate that immunoscintigraphy with the Fab'2 fragment of the antiadrenocortical Ac5 antibody may become a tool to localize human adrenocortical carcinoma.

Effects of alkaline buffers on cytoplasmic pH in lymphocytes

OBJECTIVE

To study experimentally possible adverse effects of bicarbonate on cytoplasmic pH.

DESIGN

Open, randomized control trial of white blood cells from human volunteers.

SETTING

Experimental laboratory in a large university hospital.

SUBJECTS

Lymphocytes prepared from human blood.

INTERVENTIONS

The fluorescent intracellular probe 2',7'-bis-(carboxyethyl)-5,6-carboxyfluorescein acetoxymethyl ester (BCECF-AM) was used to study the influence on cytoplasmic pH after the addition of different alkaline buffers to lymphocytes with normal as well as decreased initial intracellular pH.

MEASUREMENTS AND MAIN RESULTS

In normal lymphocytes, sodium bicarbonate caused a marked, dose-dependent acidification of the cytoplasm followed by a slow, often unpredictable increase. Ringer's acetate solution decreased the intracellular pH dose-dependently this acidification effect continued throughout the measurements. In contrast, trometamol (tris) and Carbicarb both caused a pronounced dose-dependent and lasting alkalinization of the cytoplasm. Tris buffer mixture (Tribonate) produced a slight initial dose-dependent acidification, followed by a slow increase in cytoplasmic pH to values above those recorded during control measurements. Lymphocytes that were preincubated in acetate showed similar results after addition of tris buffer mixture or sodium bicarbonate. Lymphocytes with intracellular acidosis due to preincubation in an acid buffer demonstrated a more pronounced and dose-dependent decrease of cytoplasmic pH immediately after addition of the bicarbonate-containing buffers (sodium bicarbonate and tris buffer mixture). The decrease was only partly compensated for over the next 10 mins. Only the buffers that were not producing CO2 could fully compensate for the severe extra- and intracellular acidosis imposed on the lymphocytes by preincubation in an acid medium.

CONCLUSION

Use of bicarbonate-containing buffers often results in an initial decrease of cytoplasmic pH.

MHC class I and II antigen expression on parathyroid cells and prospects for their allogenic transplantation

Homologous parathyroid transplantation has been utilized with rare success in patients suffering from parathyroid hypofunction. Major factors determining the possibility for such transplantation comprise the hitherto essentially unexplored expression and inducibility of MHC class I and II antigens on parathyroid cells. Cryosectioned and dispersed normal human parathyroid tissue displayed no or very low immunohistochemical reactivity for both class I and II antigens on the parenchymal cells, whereas the adenomatous and hyperplastic parenchyma of pathological glands encompassed a higher expression of these antigens. Monolayer culture of parathyroid cells in the presence of IFN-alpha or IFN-gamma induced class I and II antigens on the abnormal but not on the normal parathyroid cells, and no detectable induction of these molecules was obtained by varying the extracellular calcium concentration. The results indicate that normal parathyroid cells may constitute candidates for allogenic transplantation, and that further studies on the modulation of MHC-coded molecules in these cells should facilitate the utility of this potential therapy.

Incidence, structure, and function of enlarged parathyroid glands discovered accidentally during thyroid surgery

BACKGROUND

Operation on rare patients with mainly a severe renal stone disease and considerably elevated urinary calcium excretion has substantiated the association of parathyroid gland abnormalities with normocalcemia. This study examines incidence, structure, and functional characteristics of enlarged parathyroid glands of patients with normocalcemia scheduled for thyroid surgery.

METHODS

Eleven enlarged parathyroid glands weighing 110 to 1000 mg were discovered in 9 (1.5%) of 594 patients with normocalcemia undergoing thyroid operation. The preoperative total serum calcium concentration was 2.30 to 2.52 mmol/L and less than 2.38 mmol/L in four of the nine patients. Intact serum parathyroid hormone and alkaline phosphatase levels were elevated in only one individual, and all patients showed normal serum creatinine values.

RESULTS

All but three of the 11 enlarged parathyroid glands exhibited microscopic abnormality on routine histopathologic examination, including staining for cytoplasmic fat with oil red 0. Immunohistochemical staining with a monoclonal antibody recognizing the functionally important calcium receptor of the parathyroid cell surface and analysis of the calcium-regulated cytoplasmic Ca2+ concentration of dispersed parathyroid cells substantiated that only a single gland of 130 mg had no discernible functional abnormality.

CONCLUSIONS

The findings underline the diagnostic difficulties of parathyroid histopathology and support the presence of disturbed parathyroid hormone secretion even in normocalcemic patients with enlarged parathyroid glands. The functional derangement of these glands substantiates the indication for their surgical excision even in patients exhibiting midnormal serum calcium concentrations, although their possible contribution to the development of a clinically overt hyperparathyroidism can only be speculated.

Immunoelectron microscopical evidence of a calcium receptor function in parathyroid, placenta and kidney

The parathyroid, kidney and placenta have been investigated for ultrastructural signs of immunostaining with a murine monoclonal IgG 1-antibody denoted E11. Dispersed cells and tissue sections revealed a finely granular, electron dense precipitate after fixation with periodate-lysine-paraformaldehyde and indirect immunoperoxidase staining with the native or biotinylated antibody. This precipitate was confined to the surface membrane of parathyroid chief cells of normal and adenomatous human glands as well as the bovine and rat parathyroid parenchyma, preferentially the brush border membrane of proximal tubular cells in the human, rat and mouse kidney, cytotrophoblast cells of the human placenta, and trophoblast cells lining fetal blood vessels in the rat placenta. Since the E11 antibody recognizes a large glycoprotein regulating intracellular calcium mobilization and cation fluxes across the cell membrane, the present findings suggest the existence of a similar calcium receptor function on cells involved in different aspects of the calcium homeostasis within a variety of species.

Distribution of monoclonal antiparathyroid antibody E11 in mice grafted with human parathyroid adenoma and carcinoma

One hundred six immunoincompetent mice grafted with human parathyroid adenoma or carcinoma were used to evaluate distribution of the murine monoclonal antibody E11, which recognizes a calcium sensor of high molecular weight on the parathyroid cell surface. The subcutaneous parathyroid grafts were infiltrated with murine fibrous tissue, which seemed to increase with the duration of transplantation and the size of inserted tissue pieces. Intraperitoneal injection of biotinylated or 125I-labeled E11 antibody indicated time- and dose-dependent antibody accumulation, as well as the presence of unoccupied binding sites in the transplanted parathyroid tissue. The iodinated intact immunoglobulin G and Fab fragment of the E11 antibody demonstrated low radioactivity in the lung, liver, spleen, kidney, and intestine for up to 14 days, except for the Fab fragment, which was rapidly accumulated and cleared from the kidney. The peak radioactivity ratio in the adenoma tissue versus blood averaged 2.8 for the intact antibody and 5.3 for the Fab fragment, whereas the corresponding values for the carcinoma tissue were 8.6 and 8.8, respectively. These ratios increased considerably, especially for the adenoma specimens, when weights of the excised grafts were adjusted for the calculated content of parathyroid tissue. The results support that the E11 antibody may localize even minute amounts of human parathyroid adenoma and carcinoma tissue.

A retroviral gp70-related protein is expressed at specific stages during mouse oocyte maturation and in preimplantation embryos

Mouse monoclonal antibodies directed against different epitopes of the murine leukemia virus envelope protein gp70 were used to study the expression of retroviral related env proteins during mouse oocyte maturation, fertilization and blastocyst formation. A gp70-related antigen was detected with immunohistochemistry in growing oocytes but not in primordial and primary non-growing oocytes. Atretic oocytes were also negative. Both parthenogenetically activated and fertilized oocytes were positive. Two-cell stages showed a patchy distribution of the antigen. Later preimplantation stages were negative except for a markedly positive period during compaction of the morula and adhesion of the blastocyst.

Microfluorometric measurements of cytoplasmic calcium in chief and oxyphil parathyroid cells of adenomatous and hyperplastic glands and of normal-sized glands associated with adenomas

The effects of extracellular calcium on the cytoplasmic Ca2+ concentration (Ca2+i) were studied by dual-wavelength microfluorometry in individual human parathyroid cells obtained from adenomatous glands and normal-sized glands associated with adenomas in hypercalcemic hyperparathyroidism (HPT), as well as from enlarged glands of patients with uremia with HPT. In comparison with the normal parathyroid tissue, chief cells of the adenomatous and hyperplastic glands showed significantly lower Ca2+, and also right-shifted responses of Ca2+i to increases in the extracellular calcium concentration within the 0.5 to 3.0 mmol/L range. This pathophysiologic disturbance apparently was independent of the cell size. Oxyphil cells of nodules from the hyperplastic glands had lower Ca2+i and responded less to increments in extracellular Ca2+ than the chief cells from the surrounding parts of the same glands. Also the chief cells from the normal-sized glands associated with single adenomas exhibited a disturbance of the regulation of Ca2+i, which was less pronounced than that in the cells of the adenomas. These findings support the presence of relative calcium insensitivity of Ca2+i in chief and oxyphil parathyroid cells from adenomatous and hyperplastic glands. This derangement may also be found in all parathyroid glands of individuals with adenomatous HPT.