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Biomedical subjects

M Lin

Publications and source records attributed to M Lin.

At least 307 records · Page 17Linked to original sources
PubMed1993

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)

Acrosome↗
PubMed1993

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.

Antigens, Human Platelet↗
PubMed1993

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.

Acrosome↗
PubMed1993

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.

Adult↗
PubMed1993

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)

Acrosome↗
PubMed1993

Is left ventricular systolic dysfunction in hypertensive patients with heart failure normalized by long-term antihypertensive therapy?

The critical left ventricular (LV) mass when hypertensive heart failure appears, and whether LV dysfunction in hypertensives with heart failure is normalized by long-term antihypertensive therapy were investigated. LV dimension, LV mass, LV mass index, LV ejection time (LVET) and pre-ejection period (PEP) were measured in 27 normal subjects and 56 essential hypertensives, the latter divided into three groups: group I, without LV hypertrophy; group II, with LV hypertrophy; and group III, with hypertensive heart failure. LV mass and LV mass index were 135.0 +/- 23.8 g and 85.8 +/- 11.7 g/m2, respectively, in normal controls, 133.0 +/- 30.8 g and 82.0 +/- 18.4 g/m2 in group I, 222.3 +/- 38.0 g and 136.1 +/- 19.9 g/m2 in group II, and 422.0 +/- 30.3 g and 235.7 +/- 19.6 g/m2 in group III of essential hypertensives. The upper limits of LV mass and LV mass index in group II (mean + 2SD) were about 300 g and 180 g/m2, respectively. Significant shortening of LVET was observed only in group III, but PEP was prolonged with an increase in LV mass. LV diastolic dimension and PEP were not normalized by long-term antihypertensive therapy (mean: 16 months). These results indicate that the critical LV mass marking the transition from non-failing hypertrophied left ventricle to failing ventricle associated with essential hypertension is about 300 g, or LV mass index of 180 g/m2, and that LV dilatation and depressed myocardial contractility in essential hypertensives with a past history of congestive heart failure were not normalized by chronic antihypertensive therapy.

Adult↗
PubMed1993

[Studies on the chemical constituents of Populus tomentosa carr].

Populus tomentosa Carr. a Chinese folk medicine, has been used for treatment of arthritic disease. A new flavonoid(1), with molecular formula C30H26O12 was isolated from this plant along with four known compounds. They were identified as apigenin-7-O-(6"-O-p-coumaroyl)-beta-D-glucopyranoside (I), salicin (II), tremulodin (III), tremulacin (IV) and daucosterol (V) by the use of 1HNMR, 13CNMR and 1H-13C COSY spectroscopy.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1993

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.

Blood Group Antigens↗
PubMed1993

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.

Animals↗
PubMed1993

Spermatogenesis in birds.

It is concluded that in the birds which have been studied there is a well-defined, regular cycle of the seminiferous epithelium, and that spermatogenesis involves synchronization of the activities of germ cells within and between successive generations to produce cellular associations of the seminiferous epithelium which are essentially similar to those described in mammals. However, the area of a cellular association is smaller in birds than in most (and probably all) mammals so that numerous cellular associations are present in a cross-section of a seminiferous tubule. As in primates, in which a cellular association also covers a small area of seminiferous tubule, the wave of spermatogenesis in the Japanese quail follows a spiral path along and around a seminiferous tubule with consecutive stages of the cycle always occurring as adjacent stages along the tubule. The literature indicates that there are fewer mitotic divisions during spermatogonial proliferation in birds than has been reported for mammals and it is suggested that this difference explains the difference between birds and mammals in the area occupied by a cellular association. Work on the Japanese quail indicates that stem cell renewal and spermatogonial proliferation is simpler in the quail than has been described in some mammals. In the quail, both processes occur in the same compartment of the seminiferous epithelium and are synchronized with subsequent phases of spermatogenesis, and there does not seem to be a reserve pool of non-proliferating stem spermatogonia in the quail as has been reported for some mammals. Findings to date also indicate that spermatogenesis in birds is four times faster and produces four times the number of spermatozoa/g testis than in mammals, and that this difference is associated with a faster transit and poorer survival of spermatozoa in the male extragonadal ducts of birds than mammals. These differences between birds and mammals are interpreted as a response to selection pressure due to competition between males to inseminate partners frequently in order to provide the most viable spermatozoa at the site of fertilization when ova are ready for fertilization. In this respect, it is suggested that sperm production in birds and mammals have progressed along different lines of evolutionary development due to differences in ovulatory pattern and mating system. In particular, the high sperm production of birds is associated with the need to mate a (usually monogamous) partner numerous times a day over a period of days or weeks when a clutch of eggs is laid.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

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.

Animals↗
PubMed1992

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.

Journal Article↗
PubMed1992

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.

DNA↗
PubMed1992

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.

Adenosine Triphosphate↗
PubMed1992

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)

Adenosine Triphosphate↗
PubMed1992

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.

Adolescent↗
PubMed1992

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.

Adolescent↗