Right atrial pacing for risk stratification in patients with angina pectoris

Right atrial pacing (RAP) has been used to assess the physiologic impact of coronary artery disease (CAD). Several variables have served as markers of pacing-induced myocardial ischemia or for predicting disease severity, but their clinical implications remain uncertain. Therefore, three-stage RAP was performed to evaluate whether this strategy could predict the disease severity of CAD and foretell subsequent major cardiac events in 49 patients with typical chest pain. RAP was considered positive if 1 mm or more of horizontal or downward ST depression developed. Of the 49 cases, 28 had positive RAP (group A), and the remaining 21 had negative RAP (group B). For hemodynamic data, early positive RAP had the highest post-pacing left ventricular end-diastolic pressure (LVEDP). The LVEDP increased significantly in Group A (p < 0.05), whereas there was no apparent change in group B. Furthermore, group A (36%) tended to develop typical chest pain more easily than group B (14%), but this was statistically insignificant. Group A had a higher incidence of multivessel disease than that of group B (p < 0.001), whereas group A had a lower incidence of non-significant CAD than that of group B (p < 0.001). During the mean two-year follow-up period, there were 23 major cardiac events (MCE) in group A in contrast to two episodes in group B (p < 0.005). The early positive subset had 18 episodes, whereas the late positive subset had only five episodes (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

The incidence and significance of anti-"Mia" in Taiwan

BACKGROUND

The incidence of the Mill phenotype among Chinese blood donors in Taiwan is 7.3 percent. Anti-"Mia" is the most frequently occurring alloantibody of potential clinical significance encountered among Chinese patients in Taiwan, with a frequency of 0.28 percent.

CASE REPORTS

A case of hemolytic disease of the newborn and a transfusion reaction due to anti-"Mia" are described.

CONCLUSION

It may be important to include the Mill phenotype in the antibody screening of sera from Chinese patients.

Enhanced separation and detection of serum bilirubin species by capillary electrophoresis using a mixed anionic surfactant-protein buffer system with laser-induced fluorescence detection

The four major bilirubin species in serum are separated by capillary electrophoresis and detected using laser-induced fluorescence detection. The optimum buffer system consists of 40 mM sodium dodecyl sulfate (SDS)-0.012 mM bovine serum albumin (BSA). The use of the SDS-BSA mixture in the mobile phase allows for the separation of four major bilirubin species at physiological pH with untreated capillaries. The results show that the use of BSA as a run buffer modifier in SDS solution improves separation efficiency and increases sample solubility via pH changes of the run buffer. The limits of detection for the bilirubin species using laser-induced fluorescence are between 30 and 150 nM, depending on the bilirubin species; not only is this approximately two orders of magnitude lower than with visible-light absorption methods, it allows the bilirubin species in normal sera to be quantitatively measured without sample pretreatment.

Antibody-antigen binding constants determined in solution-phase with the threshold membrane-capture system: binding constants for anti-fluorescein, anti-saxitoxin, and anti-ricin antibodies

Affinities of various monoclonal and polyclonal antibodies for fluorescein-containing antigens, saxitoxin and ricin, were determined by using a light addressable potentiometric sensor-based system (Threshold). The dissociation constants, determined from Scatchard plots, ranged from 2 x 10(-7) to approximately 3 x 10(-12) M. Dissociation constants for fluorescein and saxitoxin were compared with values determined by independent means. This technique was found to be quick, simple, reproducible, and accurate.

Postnatal development of red cell Le(a) and Le(b) antigens in Chinese infants

Lewis phenotyping of 487 blood samples from Chinese newborn infants and young children, revealed that 50% of cord cells were Le(a-b+) and 50% Le(a-b-). The weak Leb antigen of Le(a-b+) cord cells is most likely produced by the newborn infant rather than of maternal origin and it appears that these infants eventually develop by way of an intermediate Le(a+b+) stage into the adult Le(a-b+) phenotype. Most infants with Le(a-b-) cord cells, but not all, appear to develop through a transitional Le(a+b-) stage, into Le (a+b+) by about 1 month of age, most likely continuing as such into adulthood. This development of Le(a-b-) cord cells into the adult Le(a+b+) phenotype is postulated to be the result of the weak secretor gene Se omega. Those infants with Le(a-b-) cord cells that do not convert to Le(a+b+) during the first month of life, most likely remain as such into adulthood. The blood of 120 adult voluntary blood donors, used as controls, reconfirmed adult Chinese phenotypic frequencies of approximately 70% Le(a-b+), 22% Le(a+b+) and 8% Le(a-b-).

Down-regulation of mRNA for the low density lipoprotein receptor in transgenic mice containing the gene for human cholesteryl ester transfer protein. Mechanism to explain accumulation of lipoprotein B particles

To evaluate the effects of cholesteryl ester transfer protein (CETP) on apoB-containing lipoproteins, we analyzed plasma lipoproteins from three different lines of human CETP transgenic mice, with plasma CETP concentration ranging from low (1.5 microgram/ml) to high levels (8.5 micrograms/ml). With increasing CETP concentration, very low density lipoprotein and low density lipoprotein (LDL) cholesteryl ester (CE) and apoB were progressively increased, and high density lipoprotein CE was decreased. To investigate the mechanism of accumulation of lipoproteins containing apoB (lipoprotein B), the abundance of hepatic LDL receptor mRNA was determined. LDL receptor mRNA was reduced as a result of CETP expression, with maximum repression to about 48% of the level of non-transgenic mice. Among the different lines of CETP transgenic mice there was an inverse relationship between plasma CETP concentration and hepatic LDL receptor mRNA abundance (r = -0.94, p < 0.01). CETP expression also led to increased cholesterol and cholesteryl ester content in liver and to decreased abundance of mRNAs encoding 3-hydroxy-3-methylglutaryl-coenzyme A reductase and 7-alpha-hydroxylase. Thus, CETP expression results in increased cholesteryl ester concentration in very low density lipoprotein and LDL, probably reflecting both CE transfer from high density lipoprotein and accumulation of lipoprotein B particles. The accumulation of lipoprotein B particles results from CETP-mediated down-regulation of liver LDL receptors, possibly due to enhanced return of cholesterol to the liver.

Spermiogenesis and spermiation in the Japanese quail (Coturnix coturnix japonica)

The ultrastructure of 12 steps of spermatid development and the process of spermiation are described for the Japanese quail in order to clarify the classification proposed for determining the stages of the cycle of the seminiferous epithelium (Lin et al. 1990) and to assess disagreements in the literature about sperm development in birds. It was concluded that acrosomal development involves the formation of proacrosomal granules which do not contain dense granules like the mammalian acrosome. Material which forms the perforatorium initially accumulates as a nuclear granule before appearing in the subacrosomal space. A circular and longitudinal manchette develop sequentially during nuclear elongation. Microtubules of the circular manchette initially form around several parts of the spherical nucleus of step 4 spermatids and subsequently occur most frequently around the narrowest regions of the elongating nucleus. Fibrous sheath development starts in step 2 spermatids indicating that it forms much earlier in the quail than in mammals. Spermiation differs from the process described in mammals in that the residual body is released from near the rostral end of the sperm nucleus leaving no cytoplasmic droplet in quail spermatozoa.

Induction of the marsupial sperm acrosome reaction in vitro by treatment with diacylglycerols

The diacylglycerol DiC8 (1,2-dioctanoyl-sn-glycerol; 100 mumol l-1) was found to induce acrosomal loss in 70% of wallaby spermatozoa and 40% of possum spermatozoa after incubation for 120 min. If 10 mumol calcium ionophore l-1 was present, the time required to reach these end points was reduced to 30 and 60 min, respectively. The diacylglycerol OAG (1-oleoyl-2-acetyl-sn-glycerol; 100 mumol l-1) produced some acrosomal loss, particularly when 10 mumol calcium ionophore l-1 was present, but when the ionophore was absent, results were equivocal. The other diacylglycerol tested DOG (1,2-dioleoyl-sn-glycerol; 100 mumol l-1) did not induce significant acrosomal loss in possum or wallaby spermatozoa. The concentration of DiC8 required to induce acrosomal loss in marsupial spermatozoa (50-100 mumol l-1) was relatively high compared with that for placental mammals, suggesting a less specific mode of action than enzyme activation. Of the diacylglycerols tested alone, only DiC8 led to significant loss of motility. In wallabies, this was detectable after incubation for 60 min and in possums after incubation for 120 min. The ultrastructure of the DiC8-induced acrosomal loss was essentially identical to the acrosome reaction described for a broad range of placental mammals. A membrane vesicle shroud covered the acrosomal surface of the sperm head. The vesicles appeared to be formed by multiple point fusions between the plasma membrane and the outer acrosomal membrane. The mechanism of DiC8-induced acrosomal loss remains to be established.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemolytic disease of the newborn caused by maternal anti-Dib: a case report in Taiwan

Possibly the first case of hemolytic disease caused by anti-Dib in a Chinese infant is reported. The infant developed jaundice soon after birth; based on study, the jaundice has been diagnosed as a result of maternal anti-Dib which was most likely induced by previous pregnancies. The phenotype of the mother's red cells was Di (a+b-). The frequency of the Dia antigen among Chinese in Taiwan is 3.2%. In Orientals, hemolytic disease of the newborn caused by maternal anti-Dib is likely to be more severe than that caused by anti-Dia.

Pericardiocentesis guided by two-dimensional contrast echocardiography

The clinical application of two-dimensional contrast echocardiography to pericardiocentesis was investigated in 20 patients with pericardial effusion. Multiple views were obtained to determine the ideal needle entry route. During pericardiocentesis, after 5 to 10 mL of pericardial fluid was withdrawn, 3 to 5 mL of agitated saline solution was injected through the exploring needle into the pericardium and a cloud of echoes indicated the needle's position. Contrast echoes were observed in all 20 patients. The procedure was performed smoothly in all patients except two (10%): the exploring needle was inserted into the right atrium in one patient and into the right ventricle in the other patient. The former promptly underwent a surgical drainage procedure, and the latter a second pericardiocentesis successfully guided by contrast echocardiography. The pericardial fluid was simply, safely, and successfully aspirated in the other 18 patients. We conclude that two-dimensional contrast echocardiography is valuable for locating needle position, thus facilitating successful pericardiocentesis in clinical practice.

Lysophosphatidylcholine disrupts the acrosome of tammar wallaby (Macropus eugenii) spermatozoa

The acrosomal status of wallaby spermatozoa was evaluated by light and electron microscopy after incubation in 1-100 microM lysophosphatidylcholine (LPC) for up to 120 min. Treatment with 1 and 10 microM LPC for 120 min did not lead to acrosomal loss, or detectable alteration to the acrosome, as detected by Bryan's staining and light microscopy. Incubation with 25 microM LPC had little effect on acrosomal loss, however statistically significant changes (P < 0.05) in the acrosomal matrix (altered) were detected after 10-min incubation by light microscopy. Around 50% of acrosomes were altered after 20-min incubation in 50 microM LPC (P < 0.001), and 40% of spermatozoa had lost their acrosome after 60-min incubation (P < 0.001). Treatment with 75 and 100 microM LPC led to rapid acrosomal loss from around 50% of spermatozoa within 10 min (P < 0.001), and by 60 min acrosomal loss was 70-80%. LPC, like the diacylglycerol DiC8 (1,2-dioctanoyl-sn-glycerol), is thus an effective agent to induce loss of the relatively stable wallaby sperm acrosome, and it also induces changes within the acrosomal matrix. Ultrastructure of the LPC-treated spermatozoa revealed that the plasma membrane and the acrosomal membranes were disrupted in a manner similar to that seen after detergent treatment (Triton X-100). There was no evidence of point fusion between the plasma membrane overlying the acrosome and the outer acrosomal membrane. The plasma membrane was the first structure to disappear from the spermatozoa. The acrosomal membranes and matrix showed increasing disruption with time and LPC concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Air pollution-type fluorosis in the region of Pingxiang, Jiangxi, Peoples' Republic of China

This paper reports on the epidemiology, environmental factors, geological features, and total amount of fluoride intake by residents of the Pingxiang region in the Peoples' Republic of China where there is a high incidence of endemic fluorosis. The results demonstrate that the type of endemic fluorosis is related to air pollution, the major source of which comes from coal that is burned by the residents in their homes. Air pollution also originates from the small kilns that are used to make bricks and tile. The fluorine content in the coal and mud used to mix the coal is considerably high; the content in the mud used as adobe for tiles exceeds 10,000 mg/kg. During the process of burning coal or baking bricks or tiles, a large amount of nonsoluble fluorine is converted into water-soluble fluoride, which can have major human health effects.

Frequency of platelet-specific antigens among Chinese in Taiwan

The frequencies of six platelet-specific antigens among Chinese in Taiwan are reported, which have not previously been well studied. HPA-1a (PlA1) antigen was positive in all 1100 Chinese tested. HPA-4b (Yukb) antigen was positive in all 100 persons tested. HPA-2b (Ko(a), Sib(a)) antigen was positive in 9 percent of 100 persons tested, HPA-3a (Bak(a)) in 77 percent, and NAKa in 96 percent. HPA-4a (Yuk(a)) antigen occurred in 0 percent in this study but is estimated to be present in 0.5 percent of the Taiwanese population.

The unique stability of the marsupial sperm acrosomal membranes examined by unprotected freeze-thawing and treatment with the detergent Triton X-100

In this study of the unique stability of the marsupial acrosome, experiments were carried out on the acrosomes of spermatozoa of the tammar wallaby (Macropus eugenii), common brushtail possum (Trichosurus vulpecula) and grey short-tailed opossum (Monodelphis domestica). Light microscopy showed that 4% of opossum and 15% of possum and wallaby spermatozoa lost their acrosomes after freeze-thawing. Electron microscopy revealed that freeze-thawing also induced changes in the acrosomal matrix of some acrosome intact spermatozoa. In both possum and wallaby, freeze-thawing increased the number of spermatozoa with vesiculation of the acrosomal matrix. Freeze-thawing disrupted the plasma membrane of spermatozoa but the acrosomal membranes remained intact. Immediately on addition of high concentrations of TX-100 (0.02% and 0.04%) there was significant loss of acrosomes and motility in possum and wallaby spermatozoa. Lower concentrations of TX-100 (< or = 0.01%) did not affect motility for up to 30 min in all three species, and there was no significant loss of acrosomes. Although loss of acrosomes did not occur under mild detergent treatment, 56% of wallaby and 70% of possum spermatozoa had altered acrosomes after 30 min in 0.01% TX-100. Electron microscopy revealed that acrosomes were undergoing a vesiculation process similar to that seen after freeze-thawing. Often the plasma membrane of detergent-treated spermatozoa was disrupted and had formed plasma membrane vesicles. However, the acrosomal membranes remained intact despite major changes to the acrosomal matrix. The study confirmed the remarkable stability of the marsupial acrosome and suggested that this is probably based in the acrosomal membranes.

Echocardiographic evaluation of thickened aortic valve and its relation to aortic stenosis and regurgitation

To elucidate the aging changes of human aortic valves and their relation to aortic regurgitation (AR) or stenosis (AS), consecutive echocardiographic examinations in 1601 subjects were carried out. These patients were prospectively divided into 5 groups: adolescence (< 20, N = 38); adulthood (20-39, N = 131); middle age (40-59, N-222); old age (60-79, N = 1194) and octogenarian (> = 80, N = 16). The incidence of thickened aortic valve (TAV), to be overall, was 29%. It was specifically 0% in the adolescence and adulthood, 15% in the middle age group, 35% in the elderly group and up to 69% in the octogenarian group. Among 307 subjects with TAV, the incidence of AR tended to increase with age, to be 31% in the 4th and 5th decades, 43% in the 6th and 7th decades and 62% in the 8th decades. The TAV existed more frequently over the noncoronary cusp (56%) than either left (22%) or right (22%) coronary cusp. In addition, the percentage of aortic stenosis and aortic regurgitation also tended to increase with age. In conclusion, TAV occurred more frequently at the noncoronary cusp than at the right or left coronary cusp. The incidence of TAV and the associated AS and AR tended to increase with age.

Expression of intermediate filaments and other special markers by testicular germ cell tumors. With reference to embryogenesis

Distribution of intermediate filament proteins (IFs) and several special markers was studied in 39 testicular germ cell tumors and 8 embryos and foetuses. The similarity and difference between development of germ cell tumor and embryogenesis were immunohistochemically investigated. Seminoma and embryonal carcinoma, as tumoral counterparts of undifferentiated germ cells, were characterized by little IF expression. This study revealed that the maturing and differentiating process in germ cell tumor is different from normal embryonal development and the tumor cells showed leaping maturing steps in tumorigenesis. Immunostaining for IFs helped to discover the further differentiation occurring in embryonal carcinoma and to demonstrate heterogeneous elements in non-seminoma germ cell tumors, which sometimes might not be apparent by light microscopical observation of H&E staining section. According to the findings, two patterns in mixed germ cell tumors are suggested; i.e., combined and diffuse types. The mechanism of tumorigenesis of the two types is supposed to be different. Clinically, the prognosis of most patients with testicular germ cell tumor is fairly good because of the improved chemotherapies that are dependent on histological diagnosis.

Haemodialysis as a model for studying endogenous plasma DNA: oligonucleosome-like structure and clearance

The rate of clearance of extracellular plasma DNA in man has important implications for pathogenetic mechanisms in systemic lupus erythematosus (SLE), as well as for certain other clinical states. Present knowledge of this parameter is derived exclusively from studies of injected, naked DNA in animals. Recent information indicates that the physiologic form of plasma DNA in SLE is that of oligonucleosome-like molecules rather than of naked DNA and consists of multimeric complexes of DNA bound to histone, probably arising from an apoptotic process. In order to study the rate at which these oligonucleosome-like complexes are removed from plasma and to do so in man rather than experimental animals, we exploited the observation that during haemodialysis large amounts of DNA are released, apparently within the dialysis coil, into the patient's plasma. Since this release appears to cease promptly with termination of the procedure, it offered the potential for estimating the rate of removal of such DNA from human plasma. Moreover, if that DNA, as postulated, were shown to possess an oligonucleosome-like structure resembling that found endogenously in human SLE, the relevance of such information to the human disease state would be further enhanced. The present results support the conclusion that DNA released into plasma during haemodialysis possesses such an oligonucleosome-like structure. The plasma half-life of that DNA in man was found not to exceed 4 min. The highly dynamic state thus implied for extracellular endogenous plasma DNA in man has important implications for pathogenetic mechanisms dependent on dsDNA in SLE. Moreover, individuals undergoing chronic haemodialysis, who are thereby exposed to a very large cumulative amount of such DNA, might serve as models for studying its long-term sequelae.

[A study on measles vaccination rate and its antibody level in children aged 12-24 months in Guangxi, 1989]

This report described the measles vaccination rate (MVR) as well as its HI antibodies of 1842 children aged from 12 to 24 months. The MVR was 99.57% but HI positive rate was only 83.50%. HI of 298 target children still remained negative. Among them, 6 children were unvaccinated and others vaccinated. The HI negative rate reached 16.50% The HI positive rate was higher in the target children who lived in the area with convenient transportation and relatively low atmospheric temperature, and who received measles vaccine at the age of 8 months or more. Otherwise, the HI positive rate was lower. So some suggestions were proposed that the vaccination season, age of vaccine, increasing vaccine dosage should be considered carefully before measles vaccination session had arranged.

cGMP-dependent protein kinase regulation of a chloride channel in T84 cells

Chloride channels at the apical membrane of intestinal epithelial cells are involved in the excessive fluid secretion in diarrhea and diminished secretion in cystic fibrosis (CF). Diarrhea induced by heat-stable toxin from Escherichia coli is associated with elevated guanosine 3',5'-cyclic monophosphate (cGMP) in intestinal epithelial cells, but it is unknown whether chloride secretion is regulated by cGMP directly or via cGMP-dependent protein kinase (PKG). Single-channel recordings (inside-out excised patches) from the apical membrane of T84 cells reveal a 10-pS chloride channel with a linear current-voltage relationship, which is opened when an endogenous membrane-bound PKG is activated with ATP (1 mM) and cGMP (100 microM). Soluble PKG (200 nM) isolated from bovine lung, added to the intracellular face of patches, also opens this channel. No activation occurs with Ringer solution alone or only ATP or cGMP. Addition of nonhydrolyzable forms of ATP (AMP-PNP, 1 mM) or a combination of ATP, cGMP, plus H-8 (5 microM), an inhibitor of PKG, also does not stimulate the channel. The catalytic subunit of adenosine 3',5'-cyclic mono-phosphate-dependent protein kinase (PKA, 200 nM, with 1 mM ATP) activates a channel with similar characteristics. The 10 pS channel has a PNa/PCl ratio of 0.06, an anion selectivity of Br- (1.2) greater than Cl- (1.0) greater than I- (0.8) greater than F- (0.4), and a low affinity for the chloride channel blockers, 4,4-dinitrostilbene-2,2-disulfonic acid and 5-nitro-2-(3-phenylpropylamino)benzoic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Contraction of glycerinated rabbit slow-twitch muscle fibers as a function of MgATP concentration

We have measured the isometric tension and force-velocity relationships of glycerinated rabbit slow-twitch semimembranosus muscle as a function of MgATP concentration ([MgATP]) and have compared the results with those obtained previously from fast-twitch psoas muscle. We find that isometric tension decreases as [MgATP] increases. The magnitude of the decrease is not as great as observed in psoas. Maximum shortening velocity (Vmax) exhibits classical Michaelian saturation behavior with respect to [MgATP] with a Michaelis constant (Km) for half-maximal velocity of 18 microM and a value at saturating [MgATP] of 0.6 muscle lengths/s. Similar values were observed in fibers from soleus, another slow-twitch muscle. The corresponding values in rabbit psoas muscle are 150 microM and 1.6 lengths/s. Compared with psoas, in semimembranosus muscle Km decreases by a factor of approximately 10, whereas Vmax decreases by about a factor of 3. Thus, although in a nonphysiological regime, at low [MgATP], a "fast" muscle actually has a lower shortening velocity than a "slow" muscle.

Renewal and proliferation of spermatogonia during spermatogenesis in the Japanese quail, Coturnix coturnix japonica

Four different types of spermatogonia were identified in the seminiferous tubules of the Japanese quail: a dark type A (Ad), 2 pale A types (Ap1 and Ap2), and a type B. A model is proposed describing the process of spermatogonial development in the quail. The Ad spermatogonia are considered to be the stem cells. Each divides to produce a new Ad spermatogonium and a Ap1 spermatogonium during Stage IX of the cycle of the seminiferous epithelium. An Ap1 spermatogonium produces two Ap2 spermatogonia during Stage II of the cycle, Ap2 spermatogonia produce four type B spermatogonia during Stage VI of the cycle, and type B spermatogonia produce eight primary spermatocytes during Stage III of the cycle. Consequently, 32 spermatids can result from each division of an Ad spermatogonium. Spermatogonial development in the quail differs from the process described in mammals in that there are fewer mitotic divisions and they are all synchronized with the cycle of the seminiferous epithelium. It is suggested that the fewer mitotic divisions explain why a smaller area of the seminiferous tubule is occupied by a cellular association in the quail than in mammals like the rat, ram and bull. The duration of spermatogenesis from the division of the Ad spermatogonia to sperm release from the seminiferous epithelium was estimated to be 12.77 days.

Nosocomial outbreak of scabies

Scabies is a common infestation caused by the human itch mite Sarcoptes scabiei. Small outbreaks in communities or hospitals are not uncommon, but are rarely documented. In this paper, we report on a nosocomial outbreak of scabies originating from a patient with Norwegian scabies at the Intensive Care Unit in Taiwan Provincial Tainan Hospital. Twenty-nine individuals including four inpatients and 25 hospital personnel were involved. The diagnosis was based on history, clinical findings or a positive skin scraping. Unfamiliarity with the clinical manifestations delayed the diagnosis and the highly contagious nature of Norwegian scabies precipitated this outbreak. Early initiation of effective control measures with extensive therapeutic and prophylactic treatment of all contacts resulted in successful eradication of the outbreak.

Purification and Molecular and Immunological Characterization of a Unique Phosphoribulokinase from the Green Alga Selenastrum minutum

A unique phosphoribulokinase (ADP:D-ribulose 5-phosphate 1-phosphotransferase, EC 2.7.1.19) has been purified to homogeneity from the green alga Selenastrum minutum. The enzyme has a native molecular mass of about 83 kilodaltons and a native isoelectric point of 5.1. The enzyme consists of two different-sized subunits of 41 and 40 kilodaltons, implying that it is a heterodimer. This is the first report of a eukaryotic heterodimeric phosphoribulokinase. The in vivo existence of two nonidentical subunits of S. minutum phosphoribulokinase was confirmed by western blot analysis of crude protein extracts from trichloroacetic acid-killed cells. These two subunits were immunologically similar, as rabbit immunoglobulin G affinity purified against the 41 kilodalton subunit of S. minutum phosphoribulokinase (PRK) cross-reacts with the 40 kilodalton subunit and vice versa. Antibodies against S. minutum phosphoribulokinase also cross-react with the spinach enzyme. NH(2)-terminal sequencing revealed that the two S. minutum PRK subunits shared a considerable degree of structure homology with each other and with the enzymes from spinach and Chlamydomonas reinhardtii, but not with PRK from Rhodobacter sphaeroides. There are, however, differences between the NH(2)-terminal amino acid sequences of the two S. minutum PRK subunits, that imply that they are the products of separate genes or products of two different mRNAs spliced from a single gene.

Ultrastructure of the Genital Duct Epithelium of the Male Port Jackson Shark, Heterodontus-Portusjacksoni

The genital ducts of Heterodontus portusjacksoni are lined by a ciliated epithelium. In the ductuli efferentes the epithelium is low and contains numerous intraepithelial leucocytes which often contain large dense bodies. All epithelial cells are ciliated and are characterised by apical vesicles, vacuoles and glycogen granules, some rough endoplasmic reticulum, dense bodies and lipid droplets, and a Golgi apparatus. The initial segment of the ductus epididymidis is lined by a very tall epithelium of ciliated and non-ciliated cells. The non-ciliated cells contain numerous apical vesicles, a large Golgi apparatus and numerous mitochondria and secretory granules in close association with an extensive endoplasmic reticulum. The terminal segment of the ductus epididymidis is lined by a low columnar epithelium. A proximal region, occupying part of the head of the epididymis, is similar to the epithelium in the ductuli efferentes. Distally, all the epithelial cells are ciliated. They are characterised by considerable dilated endoplasmic reticulum, a Golgi apparatus, apical vesicles, and numerous mitochondria and secretory granules. The secretory tubules of Leydig's glands are lined by a very tall epithelium with non-ciliated cells containing extensive, dilated, rough endoplasmic reticulum, a large Golgi apparatus, and numerous mitochondria and secretory granules. The significance of the structural differentiation of the duct is discussed in relation to the evolution of the mammalian epididymis.

Comparisons of long-term effects between converting enzyme inhibitors and conventional therapy in treating mild to moderate hypertension

A group of consecutive 180 veteran patients with mild to moderate essential hypertension were chosen to participate in clinical antihypertensive trial for the purpose of defining the role of converting enzyme inhibitors and renin-angiotensin-aldosterone system in the management of mild to moderate hypertension patients. After a two-week placebo period, these patients were randomly assigned to regimens of converting enzyme inhibitors (enalapril or captopril with or without diuretics) or conventional therapy (diuretics with or without traditional vasodilators with or without beta-blockers). Each patient was regularly followed up every two weeks and doses were added until the diastolic blood pressure was equal to or lower than 90 mmHg. After 1 year of follow-up, only 162 patients completed the study. All high blood pressure was significantly reduced by these three regimens, but no significant difference of blood pressure control was noted. The mean left ventricular ejection fraction increased from 55.9 +/- 6.2 to 57.5 +/- 5.3% in captopril group (P less than 0.05, n = 59) and from 54.8 +/- 6.8 to 57.2 +/- 5.8% enalapril group (P less than 0.01, n = 53), in contrast to the insignificant change in control group (n = 50) (56.5 +/- 7.7 to 56.6 +/- 5.9%). The exercise duration also significantly increased only in converting enzyme inhibitors group (P less than 0.01). Furthermore, the plasma aldosterone level was significantly reduced by converting enzyme inhibitors therapy, whereas conventional therapy had no beneficial effect (P less than 0.01). Furthermore, the plasma aldosterone level was significantly reduced by converting enzyme inhibitors therapy, whereas conventional therapy had no beneficial effect (P less than 0.001). Concomitantly, antidiuretic hormone and plasma norepinephrine levels were also significantly reduced by converting enzyme inhibitors. In addition, converting enzyme inhibitors had a favorable trend to affect the metabolism of lipid in contrast to the conventional therapy. These results show that a first-step treatment of hypertension with converting enzyme inhibitors permits better left ventricular function and improves exercise tolerance by way of renin-angiotensin-aldosterone system inhibition. Thus, converting enzyme inhibitors might be suggested as the first step regimen in the treatment of hypertension.

Argyrophilia in ovarian serous tumors. A comparative study in 127 epithelial ovarian tumors

The distribution of argyrophil cells in epithelial ovarian tumors was studied in 127 cases. The results showed that not only mucinous tumors and endometrioid tumors contained argyrophil cells, but also some serous tumors expressed argyrophilia. 31% of serous tumors including 40% of serous adenocarcinomas contained variable numbers of argyrophil cells. Argyrophilia has been demonstrated in mucinous tumors, endometrioid tumors and Brenner tumors before. However, this is the first time the presence of argyrophilia in serous tumors has been noticed. Moreover, the argyrophil cells in 5 serous carcinomas showed reactivity with Neuroendocrine (chromogranin A) antibody but not with serotonin. The expression pattern of argyrophilia in the serous tumors was different from that of the mucinous tumors; in the former, argyrophil granules appeared in apical portions or throughout the cytoplasm of single or clustered cells. In addition, the argyrophilia in some serous tumors and endometrioid tumors decreased after diastase digestion. Ultrastructurally, no typical neurosecretory granule was found in the argyrophilic serous tumors. The findings in this study suggest that argyrophilia could be quite frequently found in ovarian epithelial tumors and in itself is not a very specific differential characteristic of carcinoid tumors. The argyrophilia found in a variety of epithelial ovarian tumors might lend additional support to the histogenesis and close relationship between the common epithelial tumors of the ovary.

The efficacy of early continuous positive airway pressure therapy in patients with acute cardiogenic pulmonary edema

Although continuous positive airway pressure (CPAP) therapy using a face mask is known to improve oxygenation, the intrapulmonary shunt reduction remains unsettled. Our study was designed to explore this issue. From 1985 to 1987 80 patients with acute cardiogenic pulmonary edema were randomly chosen to receive either serial CPAP therapy or high-flow face mask oxygen therapy without CPAP (control) for the purpose of evaluating the efficacy of CPAP therapy. After screening for exclusion, only 55 patients were included in the first 3-hour investigation period. PaO2 in the CPAP group showed a significant increase by the end of the initial study; whereas intrapulmonary shunt and alveolar-arterial oxygen tension gradient AaDO2 revealed simultaneously a significant reduction. Conversely, neither PaO2 nor intrapulmonary shunt (or AaDO2) in the control group demonstrated any significant beneficial changes. As for cardiovascular function, only the CPAP therapy achieved a significant reduction in rate pressure product in contrast to the control (face mask) therapy alone. In terms of therapeutic failure, 10 patients in the control group failed. However, in the CPAP group only 5 patients had failed at the end of the first 3-hour study period. Overall, the cumulative therapeutic failure rate was 28% in the CPAP group and 60% in the control group during a 6-hour observation study. However, there was no significant difference between the two groups in 24-hour hospital mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Enalapril in congestive heart failure: acute hemodynamic and neurohumoral evaluation and short-term follow-up

The acute efficacy of rapid loading of oral long-acting enalapril in congestive heart failure remains to be established. We evaluated the efficacy of this treatment modality in 22 patients with chronic congestive heart failure N.Y.H.A. functional class ranging from II-IV with Creatinine level less than 2 mg/dl. Following hemodynamic evaluation, there was significant favorable change in the left ventricular functional curve. Moreover, acute hemodynamic assessment showed a significant reduction in pulmonary capillary wedge pressure from 19.2 +/- 4.8 to 17.2 +/- 4.7 mmHg (p less than 0.005) and an increases in stroke volume index from 28.3 +/- 9.2 to 33.1 +/- 7.5 ml/m (p less than 0.005). After rapid enalaprilization, blood pressure fell from 127 +/- 21/78 +/- 15 to 108 +/- 21/68 +/- 15 mmHg (p less than 0.005), systemic vascular resistance from 1725 +/- 602 to 1370 +/- 376 dyne.sec.cm-5 (p less than 0.05) and pulmonary vascular resistance from 262 +/- 19 to 218 +/- 65 dyne.sec.cm-5 (p less than 0.05). Cardiac index rose significantly from 2.43 +/- 0.62 to 2.60 +/- 0.50 l/min/m2 (p less than 0.05). In terms of neurohumoral assessments, there was a significant inhibition of the renin-angiotensin-aldosterone system. Aldosterone fell from 21.3 +/- 13.4 to 9.4 +/- 8.0 ng/dl and plasma renin activity rose from 3.3 +/- 4.6 to 11.3 +/- 11.0 ng/nl/hr (p less than 0.005). Plasma norepinephrine and epinephrine levels were found to have significant reduction in addition to antidiuretic hormone concentration. During short-term trial, left ventricular ejection fraction was significantly elevated from 27.5 +/- 6% to 32.8 +/- 10.8% (p less than 0.005). Thus, this limited study clearly demonstrates the rapid administration of enalapril not only achieves inhibition of renin-angiotensin-aldosterone system but also reduces preload and afterload significantly in the failing heart. We conclude that rapid enalaprilization is an effective methodology which still needs meticulous attention, providing significant hemodynamic and symptomatic benefits in patients with chronic congestive heart failure.

Comparison of enalapril and conventional vasodilator therapy in patients with chronic congestive heart failure

The aim of this study was to investigate the role of the renin-angiotensin-aldosterone system during anti-heart failure treatment with additional enalapril versus conventional vasodilator therapy (hydralazine + sorbitrate) and to assess whether or not enalapril can be suggested as the preferential vasodilator therapy in patients with chronic congestive heart failure. Over a 2.5-year period, 120 patients (New York Heart Association II-IV, creatinine less than or equal to 2.0 mg/dl) were enrolled in the study and randomly assigned to receive enalapril or hydralazine and sorbitrate therapy in addition to optimal digitalis and diuretics administration. At the end of a one-year followup, there was a tendency for mortality to be lower in the enalapril[correction of enlapril] group (4 cases) compared to the conventional group (9 cases), but the difference was not significant (p = 0.21). Both groups showed similar increases in plasma renin activity. The plasma aldosterone level decreased significantly in the enalapril group (p less than 0.005); whereas it rose significantly in the conventional group (p less than 0.005). The plasma norepinephrine level of the enalapril group fell significantly when compared with the conventional group. Thus, enalapril therapy achieved better reduction in the activating sympathetic system (p less than 0.0001). Reduction in the anti-diuretic hormone level was also found to be highly significant in the enalapril group, whereas no difference was seen in the conventional group. Furthermore, the serum creatinine level and blood urea nitrogen remained unchanged in the conventional group; whereas both were demonstrated to be reduced significantly in the enalapril group at a 1-year follow up.(ABSTRACT TRUNCATED AT 250 WORDS)

Intracellular heterogeneity in mitochondrial membrane potentials revealed by a J-aggregate-forming lipophilic cation JC-1

By using a potential-dependent J-aggregate-forming delocalized lipophilic cation, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine++ + iodide (JC-1), we find that membrane potentials across mitochondria in a living cell can be heterogeneous. Remarkably, even within a long contiguous mitochondrion, regional heterogeneity in membrane potentials appears to be possible.

Replication of ocular isolates of human adenovirus is serotype-dependent in rabbit corneal organ culture

The goal of the present in vitro study was to determine the ability of unadapted human adenoviral ocular isolates to replicate in the rabbit cornea. Rabbit corneas grown in organ culture (24 well plate) were inoculated topically with 50 microliters (5 x 10(5) pfu) of different ocular adenoviral serotypes (ATCC and clinical isolates). Control wells (no cornea present) were inoculated in a similar fashion. Viral replication was determined by serial aliquots titrated on A549 cells. We demonstrated sustained viral replication over time of all isolates (100%) of Ad1, 2, 5, 6, 8, 9, 11 and 37 tested. No isolates (0%) of Ad3, 7A, 19, and 4 demonstrated replication in our model. Peak titers varied among successful serotypes from 10(2) pfu/ml (Ad11) to 10(5) PFU/ml (Ad5), and among different isolates of a given serotype. We conclude that the ability of unadapted human Ad serotypes to replicate in rabbit corneas was serotype-dependent, and that subgroup C (Ad1, 2, 5, and 6) appeared to be the most successful subgroup.

Hemodynamic response to BMI model PIAB catheter

Using the BMI model PIAB catheter designed and produced by our laboratory, we carried out serial animal experiments to evaluate its hemodynamic effects in goats. The animal experiments and comparison tests indicated that BAPDP = 24, PSP = 22; BAEDP = 8, EDP = 14; BAPSP = 20, PSP = 22. The various hemodynamic parameters of our PIAB catheter are equivalent to or better than those of imported products. But the price of our PIAB catheter is much lower than that of foreign products. It has been used in some hospitals, showing satisfactory results.

S-100 protein in ovarian tumors. A comparative immunohistochemical study of 135 cases

The distribution of S-100 protein in 135 ovarian tumors, of which 127 were epithelial, was investigated using the immunoperoxidase method. S-100 protein has been demonstrated previously in tumors of various origins. The present study further revealed its characteristic distribution in common epithelial tumors of the ovary. S-100 protein was present in 69% of serous tumors (benign, 50%; borderline, 100%; malignant, 71%), as well as in the serous elements of serous & mucinous mixed tumors (30%). S-100 protein was also demonstrated in 25% of clear cell carcinomas and 29% of endometrioid carcinomas. Interestingly, none of the mucinous tumors were positive for S-100 protein. In addition, the expression of S-100 protein by epithelial ovarian tumors was compared with that of CA 125 and carcinoembryonic antigen (CEA). The distribution of S-100 protein was similar to that of CA 125, since both antigens were frequently present in serous tumors, although their expression patterns were different. On the other hand, S-100 protein-positive cases were almost negative for CEA or vice versa. Our observations indicate that demonstration of S-100 protein in common epithelial tumors of the ovary and comparison of S-100 protein distribution with that of CA 125 and CEA may further clarify the characteristics of common epithelial tumors of the ovary.

Evidence for intraluminal Ca++ regulatory site defect in sarcoplasmic reticulum from malignant hyperthermia pig muscle

Malignant hyperthermia (MH) is a pharmacogenetic disease of humans and various animal species that predisposes to a life-threatening, anesthetic agent-induced syndrome. MH is thought to be a consequence of abnormal, sustained increases in myoplasmic Ca++ and sarcoplasmic reticulum (SR) membranes from MH muscle have been shown to have a Ca++ release channel defect. In the present study we have tested a hypothesis that the abnormal Ca++ release mechanism in MH can be expressed when Ca++ is loaded in the presence of pyrophosphate. SR membrane vesicles isolated from normal and MH pig muscle were loaded with Ca++ in the presence and absence of pyrophosphate until Ca(++)-induced Ca++ release occurred. Under both circumstances the threshold amount of Ca++ loaded until Ca++ release occurred was lower in the SR from MH pig skeletal muscle. This difference in amount of Ca++ preload is not explained by results obtained comparing rates of Ca++ uptake, number of ryanodine binding sites or the amounts of calsequestrin among SR vesicles from MH and normal muscle. We conclude from this study that use of pyrophosphate for Ca++ loading does not ablate the abnormal Ca++ release in SR from MH muscle, suggesting the study can be done on small amounts of SR from biopsied human muscle. The data also suggest that abnormality in an intraluminal, low affinity Ca++ binding site regulating Ca++ release occurs in the SR membrane of MH pig muscle.

Atypical lipoleiomyoma of the uterus

A case of uterine atypical lipoleiomyoma in a 55-year-old obese woman is described. Histologically it was composed of atypical smooth muscle tissue and adipose tissue, as proved by immunohistochemical staining and ultrastructural study. Moreover, these studies revealed a transition from tumor smooth muscle cells to lipocytes. The features of this tumor suggest that at least some lipoleiomyomas result from lipomatous metaplasia of leiomyoma. Lipoleiomyoma is a rare lesion of the uterus, and the present tumor with an atypical leiomyomatous appearance is the first reported case of its kind. A review of previous case reports, together with the condition of this patient, revealed that patients with lipoleiomyoma are often overweight and menopausal, and have a high incidence of gallbladder disease.

Spatial arrangement of the stages of the cycle of the seminiferous epithelium in the Japanese quail, Coturnix coturnix japonica

The spatial arrangement of the stages of the cycle of the seminiferous epithelium of the Japanese quail was investigated by preparing three-dimensional reconstructions of a seminiferous tubule from each of 3 quails. It was found that the stages were not distributed at random, but were arranged in a wave which spiralled helically along a seminiferous tubule. Adjacent stages in space were always adjacent numbers in the cycle of the seminiferous epithelium. Complete spermatogenetic waves were found in which all 10 stages of the cycle were in sequential order. However, in most waves the sequential order of stages was disturbed by the occurrence of modulations. The area of a cellular association varied from 4600 to 41,600 microns 2 with a mean +/- s.e.m. (3 animals) of 17,902 +/- 2614 microns 2. The number of Sertoli cells involved in an association ranged from 4 to 35, with a mean +/- s.e.m. (3 animals) of 13.5 +/- 2.8. The findings support our earlier suggestion that the kinetics of spermatogenesis in the quail are fundamentally similar to the pattern which has been described for mammals.

Cytochrome and Alternative Pathway Respiration during Transient Ammonium Assimilation by N-Limited Chlamydomonas reinhardtii

Mass spectrometric analysis of gas exchange in light and dark by N-limited cells of Chlamydomonas reinhardtii indicated that ammonium assimilation was accompanied by an increase in respiratory carbon flow to provide carbon skeletons for amino acid synthesis. Tricarboxylic acid (TCA) cycle carbon flow was maintained by the oxidation of TCA cycle reductant via the mitochondrial electron transport chain. In wild-type cells, inhibitor studies and (18)O(2) discrimination experiments indicated that respiratory electron flow was mediated entirely via the cytochrome pathway in both the light and dark, despite a large capacity for the alternative pathway. In a cytochrome oxidase deficient mutant, or in wild-type cells in the presence of cyanide, the alternative pathway could support the increase in TCA cycle carbon flow. These different mechanisms of oxidation of TCA cycle reductant were reflected by the much greater SHAM sensitivity of ammonium assimilation by cytochrome oxidase-deficient cells as compared to wild type.

Primary adenocarcinoma of the female urethra with three histologic patterns and partial AFP positivity

A rare case of adenocarcinoma of the female urethra with alpha-fetoprotein (AFP) positivity in a 52-year-old woman is reported. The tumor was papillary polypoid, localized in the posterior wall of the mid-urethra and microscopically showed three histologic components. Upon immunostaining and histochemical staining, the tumor was characterized by intestinal-type cells positive for epithelial membrane antigen (EMA) and carcinoembryonic antigen (CEA), EMA-negative and AFP-positive columnar vacuolated cells and mainly EMA-positive clear cells. On the basis of these features together with the known embryogenesis of the urethra, an endodermal origin of the tumor is suggested, possibly arising from the reserve or stem cells in the urethral mucosa. This case and its immunohistochemical features are quite unique and the histologic combination is meaningful when considering the oncogenesis and histogenesis of urethral tumors.

The cycle of the seminiferous epithelium in the Japanese quail (Coturnix coturnix japonica) and estimation of its duration

A regular, well defined spermatogenic cycle was found in the Japanese quail by examining thin sections of isolated lengths of seminiferous tubules embedded in epoxy resin to resolve the structure of developing spermatids. The stages of the cycle initially were identified in studies using a preparatory method for fixation which separated adjacent cellular associations. The cycle was divided into 10 stages with relative frequencies (%) of Stages I to X respectively of: 11.9, 14.8, 24.1, 10.3, 8.2, 6.4, 9.4, 5.5, 3.8 and 5.4. The duration of one cycle was 2.69 +/- 0.08 days (mean +/- s.e.m.) as determined by intraventricular injection of [3H]thymidine and autoradiographic examination of the testes 1-4 days later. It was estimated that lifespans were 2.01 days for type B spermatogonia, 3.86 days for primary spermatocytes, 0.15 days for secondary spermatocytes, and 4.54 days for spermatids. The results suggest that the kinetics of spermatogenesis in the quail are fundamentally similar to the pattern in mammals.

Stimulation of protein secretion in the initial segment of the rat epididymis by fluid from the ram rete testis

Zone 1A of the ductus epididymidis was perfused with ovine rete testis fluid (nRTF) and modifications of it, and a synthetic medium (sRTF) based on the inorganic composition of nRTF. There was little fluid transport by the duct mucosa and nRTF stimulated protein secretion. The secretagogue activity was not extracted by charcoal, was sensitive to protease digestion and was present in a portion of nRTF with a molecular weight of greater than 10,000. The addition of bovine serum albumin to the sRTF stimulated protein secretion, but not to the same extent as equal amounts of protein in nRTF. Polyacrylamide gel electrophoresis of the perfusates showed that proteins with molecular weights of 19,000 (all rats studied), and 22,000, 30,000 and 60,000 (at least half the rats studied) were secreted into the perfusion fluids as well as some blood proteins, but the pattern of secretion was not affected by the composition of the perfusion fluid.

MR imaging of neurocysticercosis

Twenty-six patients with neurocysticercosis were studied with MR imaging to correlate their clinical presentation with the location and appearance of their neurocysticercosis lesions. Intraventricular cysts were present in 14 patients (54%), parenchymal cysts were present in 18 (69%), and intraventricular together with parenchymal cysts were present in six (23%). Intraventricular cysts were detected by mass effect, ventricular obstruction, detection of a cyst rim, and/or CSF flow void adjacent to the cyst. The intensity of most intraventricular and parenchymal cysts presumed to be viable was similar to that of CSF on both T1- and T2-weighted sequences. Cysts presumed to be degenerated had increased signal intensity on T1-weighted images, probably resulting from increased protein content. Pericystic high signal intensity surrounding lesions of various ages was seen on both proton-density- and T2-weighted images and represents gliosis, edema, and inflammation. Patients with parenchymal cysts had symptoms of seizures, while those with intraventricular cysts generally had symptoms related to obstructive hydrocephalus. Aqueductal stenosis, seen in 10 patients (38%), was possibly due to ependymal inflammation or adhesions caused by prior ventricular infection by neurocysticercosis. One patient with the racemose form of neurocysticercosis demonstrated abundant cyst wall proliferation resulting in obstructive hydrocephalus. In six patients scanned 1-6 months after oral praziquantel therapy, there was no change in the MR appearance of intraventricular cysts, while some parenchymal cysts showed evidence of degeneration. We found MR to be useful in detecting the cysts of neurocysticercosis and the accompanying signs of cyst degeneration and pericystic inflammation. MR was inferior to CT in the detection of parenchymal calcifications.

Pyruvate kinase isozymes from the green alga, Selenastrum minutum. II. Kinetic and regulatory properties

The kinetic and regulatory properties of two pyruvate kinase isozymes, PKp and PKc (apparent chloroplastic and cytosolic isozymes, respectively) from the green alga Selenastrum minutum were studied. The two isozymes differed greatly in several kinetic properties. Although both isozymes showed hyperbolic substrate saturation kinetics, the apparent Michaelis constants for PEP and ADP were about twofold and fourfold lower, respectively, for PKc as compared with PKp. ADP was the preferred nucleotide substrate for both isozymes. However, PKc utilized alternate nucleotides far more effectively than did PKp. PKc and PKp also differed strongly in the effect of activators and inhibitors on the enzymes. Although both isozymes were activated by dihydroxyacetone phosphate (DHAP) with a similar activation constant of about 30 microM, this activator (0.5 mM) caused an approximate 30% increase in the Vmax of PKc, but had no effect on the Vmax of PKp. PKp, but not PKc, was inhibited by ribose 5-phosphate, ribulose 1,5-bisphosphate, 2-phosphoglycerate, phosphoglycolate, and malate. Both isozymes were inhibited by MgATP, Mg2citrate, Mg2oxalate, and Pi. PKc was far more sensitive to inhibition by Pi, as compared with PKp. Pi was a competitive inhibitor of PKc with respect to phosphoenolpyruvate (PEP) (Ki = 1.3 mM). Glutamate was a potent inhibitor of PKc, but had no effect on PKp. In contrast with Pi, glutamate was a mixed-type inhibitor of PKc with respect to PEP (Ki = 0.7 mM). DHAP facilitated the binding of PEP by both isozymes and reversed or relieved the inhibition of PKc by Pi and/or glutamate. The regulatory properties of PKp indicate that it is likely less active in the light and more active in the dark. The in vivo activity of PKc is probably regulated by the relative cytosolic levels of DHAP, Pi, and glutamate; this provides a rationale for the activation of algal cytosolic pyruvate kinase which occurs during periods of enhanced ammonia assimilation.

Pyruvate kinase isozymes from the green alga, Selenastrum minutum. I. Purification and physical and immunological characterization

Pyruvate kinase from the green alga Selenastrum minutum consists of two isoforms (PK1 and PK2) separable by Q-Sepharose chromatography. The two isoforms have been highly purified to respective final specific activities of 42 and 23 (mumol pyruvate produced/min)/mg protein. Purification steps included salt fractionation, anion-exchange, hydrophobic interaction, and gel filtration chromatography. The final enzyme preparations differ significantly in physical and immunological properties. PK1 is heat labile and is completely inactivated following reaction with N-ethylmaleimide. In contrast, PK2 is heat-stable and is only partially inactivated following N-ethylmaleimide treatment. PK1 appears to be homotetrameric with a native molecular mass of about 240 kDa, whereas PK2 appears to be homodecameric with a native molecular mass of approximately 590 kDa. The antigenic reaction of both final PK preparations to rabbit antiserum prepared against homogeneous germinating castor bean endosperm cytosolic pyruvate kinase was tested by immunoprecipitation and Western blotting. The two algal pyruvate kinases are immunologically unrelated as only PK2 cross-reacts with the cytosolic pyruvate kinase antibodies. These data indicate that the S. minutum pyruvate kinase isoforms, PK1 and PK2, are not interconvertible forms of the same protein, but probably represent chloroplastic and cytosolic isozymes, respectively.