Fibroadhesive form of tuberculous peritonitis: chyloperitoneum in a patient undergoing automated peritoneal dialysis

Chyloperitoneum is a rare condition in patients undergoing peritoneal dialysis. We report here a patient who developed chylous ascites during the course of tuberculous peritonitis. The diagnosis was confirmed by cultures of dialysate and peritoneal biopsy, and laparoscopy revealed severe hyperemia and intestine adhesion. Intrinsic lymphatic obstruction and superimposed peritoneal fibrosis together might be responsible for the pathogenesis of this special presentation. Although in most cases of continuous ambulatory peritoneal dialysis, the causes of chyloperitoneum remained unknown, we suggest, from the experience of this case, that tuberculous peritonitis, especially the fibroadhesive form, should be highly suspected in any dialysis cases with chyloperitoneum. Laparoscopy should be initiated early, particularly when the culture is negative for common pathogens or when the patient responds poorly to the usual antimicrobial agents.

Cloning and characterization of a cDNA encoding an 18.0-kDa class-I low-molecular-weight heat-shock protein from rice

A novel cDNA clone, Oshp18.0 cDNA, encoding a rice (Oryza sativa L. cv. Tainong 67) 18.0-kDa heat-shock protein (HSP), was isolated from a cDNA library of heat-shocked rice seedlings by use of the rice HSP cDNA, Oshsp17.3 cDNA, as a probe. The sequence showed that Oshsp18.0 cDNA contains a 749-bp insert encoding an ORF of 160 amino acids, with a predicted molecular mass of 18.0 kDa and a pI of 7.3. Sequence comparison reveals that Oshsp18.0 cDNA is highly homologous to other low-molecular-weight (LMW) HSP cDNAs. Also, the results of hybrid-selected in vitro translation clearly establish that Oshsp18.0 cDNA is the rice 18.0-kDa LMW HSP-encoding cDNA clone. The recombinant Oshsp18.0 fusion protein produced in Escherichia coli was of the size predicted, and was recognized by the class-I rice 16.9-kDa HSP antiserum. The results suggest that Oshsp18.0 cDNA is an 18.0-kDa class-I LMW HSP- encoding cDNA clone from rice.

Breathing-coordinated exercise improves the quality of life in hemodialysis patients

Breathing-coordinated exercise is a traditional Chinese exercise. These exercise maneuvers consist of slow diaphragmatic breathing, end-inspiratory pause, and Kegel's exercise. A total of 30 patients were enrolled in this study, with 12 patients as controls, to evaluate its effect on hemodialysis patients. Exercise was performed for 25 to 30 min twice a day for at least 3 months. Results from the exercise group showed a subjective improvement in appetite and physical strength, and an increase in the frequency of bowel movements, in addition to enhanced sexual activity and a significant increase in Karnofsky scores. Six patients in the exercise group underwent bicycle ergometry and demonstrated a stable maximal oxygen consumption, whereas the control group revealed a decline in maximal oxygen consumption. Photoelectric plethysmography and laser-Doppler flowmetry demonstrated a pulsatile enhancement of the peripheral microcirculation. Abdominal sonography revealed an oscillatory change in the diameter of the inferior vena cava. It was concluded that these gentle exercise maneuvers may improve the quality of life in hemodialysis patients, especially weak dialysis patients. The mechanism may be partly related to an improvement in microcirculation.

A recombinant rice 16.9-kDa heat shock protein can provide thermoprotection in vitro

It is difficult to obtain large amounts of purified low-molecular-mass heat shock proteins (LMM HSPs), which are unique to plants, for biochemical and physiological studies. Therefore, an attempt was made to produce such a HSP by applying recombinant DNA technology. We fused the cDNA for a rice class I 16.9-kDa HSP, pTS1, to the gene for glutathione S-transferase (GST) of Schistosoma japonicum and we obtained large amounts of the fusion protein from transformed Escherichia coli cells. In addition, we found that the 16.9-kDa HSP obtained by cleavage of the recombinant protein could also form a protein complex of approximately 310 kDa under nondenaturing conditions as can the small, native, class I HSPs from heat-shocked rice seedlings. An assay in vitro to examine the thermoprotection of rice soluble proteins from heat denaturation revealed the strong stabilizing effect of the recombinant HSP.

Factors which influence levels of selected organisms in saliva of older individuals

The most commonly measured bacterial parameters in saliva are the levels of the mutans group streptococci and lactobacilli, which have diagnostic implications for the incidence of dental decay. Diagnostic guidelines which are applicable to children and young adults in whom most, if not all, teeth are present and in whom the rate of stimulated saliva is almost always greater than 0.5 ml/min have been developed. Dental decay is a potential health problem of considerable magnitude among elderly individuals. In elderly individuals, missing teeth, the presence of dentures, and a reduced salivary flow could confound the interpretation of salivary levels of cariogenic bacteria. In the present study, in which saliva was collected from more than 560 elderly individuals (average age, 70 +/- 8 years), there was a significant positive relationship between the salivary levels of Streptococcus mutans and increased numbers of teeth. There was a positive association between the salivary levels of S. mutans and decay when the data were stratified for the presence of a complaint of xerostomia and the presence of dentures. However, a similar analysis indicated that lactobacilli and yeasts were more likely to be associated with decay. The various variables which could influence the bacterial counts per milliliter of saliva, e.g., independent or dependent living status, complaint of xerostomia, stimulated salivary flow, salivary pH, the presence of dentures, number of teeth, and decay, were analyzed simultaneously by using a multivariable linear model. In that analysis the number of decayed teeth was significantly associated with the presence of lactobacilli (P = 0.0001) and yeasts (P = 0.025) but not with the presence of S. mutans. Our findings indicate that salivary levels of lactobacilli and yeasts, as well as the salivary levels of S. mutans, should be monitored when seeking microbial indicators that might predict the incidence of caries in elderly individuals.

Elevation of serum IL-6 levels in patients with acute bacterial infection

BACKGROUND

Serum cytokine levels have been reported to elevate in acute bacterial infection, but the relationship of differential elevation in cytokine levels to patients' clinical parameters and prognosis remains controversial. The present study was designed to evaluate whether serum interleukin-1 alpha (IL-1 alpha) and IL-6 levels were raised in patient with acute bacterial infection, and were correlated with patients clinical parameters.

METHODS

Thirty patients, aged from 20 to 91 years, calling our emergency room with clinical evidence of acute bacterial infection and marked leukocytosis, were enrolled in this study. Sera were collected immediately and analyzed for IL-1 alpha and IL-6 levels with Enzyme-Linked Immunosorbent Assay (ELISA) method.

RESULTS

All patients with acute bacterial infection had measurable higher levels of serum IL-6 than normal volunteers. Patients with higher serum IL-6 level were more likely to have fever, though without statistical significance (p = 0.09). Serum IL-6 levels did not correlate significantly with positive blood culture result, septic shock, or fatal outcome. Serum IL-1 alpha levels were below minimal detectable concentrations in all patients checked.

CONCLUSIONS

Serum IL-6 levels were elevated in patients with acute bacterial infection, and were possibly associated with the occurrence of fever. IL-1 alpha played no obvious role as systemic effector molecule in acute bacterial infection in our study.

Packing of coat protein amphipathic and transmembrane helices in filamentous bacteriophage M13: role of small residues in protein oligomerization

Filamentous bacteriophage M13, an important cloning and phage display vector, is encapsulated by ca 2700 copies of its 50-residue major coat protein (gene 8). This protein occurs as a membrane protein while stably inserted into its E. coli host inner membrane, and as a coat protein upon assembly and packing onto phage DNA in the lipid-free virion. To examine the specific protein-protein interactions underlying these processes, we used a combination of randomized and saturation mutagenesis of the entire gene 8 to assess the susceptibility of each position to mutation. In the resulting library of ca 100 viable M13 mutants, "small" residues (Ala,Gly,Ser), which constitute the non-polar face of the N-terminal amphipathic helical segment, and a face of the hydrophobic (effective transmembrane) helical segment, were found to be highly conserved. These results support a model in which coat protein packing is stabilized by the presence within each protein subunit of two "oligomerization segments", i.e. specific helical regions with faces rich in small residues which function to promote the close approach of alpha-helices.

Sequence analysis of an Erwinia stewartii plasmid, pSW100

The nucleotide sequence of the smallest plasmid of Erwinia stewartii SW2 was determined. This plasmid, pSW100 (4272 bp), consists of a 702-bp region homologous to the origins of replication of plasmids p15A, ColE1, and ColA. Plasmid pSW100 also contains sequences homologous to the bom region and mobCABD genes of ColE1, except that a single-base deletion in mobA has been detected. This deletion did not affect the mobilization ability of pSW100 by an endogenous conjugative plasmid of E. stewartii SW2, pDC250. Plasmid pSW100 also has a 1596-bp open reading frame with five 132-bp perfect repeats. However, this open reading frame and the repeats are not required for plasmid replication. Furthermore, curing of pSW100 did not cause any phenotypic change, suggesting that this plasmid is not essential for the survival of the organism.

The prognostic value of serum cytokine levels in patients with acute infections

BACKGROUND

Elevation of serum cytokine level, especially tumor necrosis factor-alpha (TNF-alpha) and granulocyte-colony stimulating factor (G-CSF), has been reported in acute bacterial infection. Elevation of serum TNF-alpha level upon patients' admission has also been reported to correlate with the fatal outcome.

METHODS

The present study is to evaluate, in addition to TNF-alpha and G-CSF, whether serum stem cell factor (SCF), interleukin-3 (IL-3) and granulocyte-macrophage-CSF (GM-CSF) levels to see if they were also elevated in patients with acute bacterial infection. It also tries to evaluate whether different degree of elevation of cytokine levels had any relationship to patients' clinical parameter, including fatality. Correlation between different kinds of cytokines was also studied.

RESULTS

Patients with bacterial growth in blood culture had higher level of serum G-CSF. Higher level of serum TNF-alpha was significantly associated with the occurrence of septic shock, but not of fatal outcome. Low serum G-CSF and high serum SCF level were significantly associated with fatal outcome; however, all the patients still had serum SCF levels within normal range. GM-CSF and IL-3 play no obvious role as systemic effector molecule in acute bacterial infection.

CONCLUSIONS

Higher levels of serum TNF-alpha are associated with the occurrence of septic shock. Low serum G-CSF levels are significantly associated with fatal outcome. Routine monitoring of serum G-CSF level in patients with severe infection in order to supplement recombinant G-CSF can possibly help patients to overcome the disaster.

Magnitude of TGF-initiated nephron-nephron interactions is increased in SHR

We compared the tubuloglomerular feedback (TGF)-initiated nephron-nephron interaction in spontaneously hypertensive rats (SHR) and normotensive Sprague-Dawley (SD) rats. Interaction strength was assessed by measuring stop-flow pressure (delta SFP) responses in pairs of nephrons, where only one nephron of the pair was microperfused. The vascular connection was determined from casts of the nephrons and vessels; length of arteriolar separation between the two glomeruli was measured on the casts. When microperfusion rate was increased from 5 to 50 nl/min, delta SFP in perfused nephrons was 10.6 +/- 0.6 and 10.2 +/- 0.7 mmHg [not significant (NS)] in SD and SHR, respectively. In the matched unperfused nephrons from the same cortical radial artery, delta SFP was 1.3 +/- 0.2 and 2.9 +/- 0.7 mmHg (P < 0.05) in SD and SHR. When the perfused and unperfused nephron originated from different cortical radial arteries, delta SFP in the unperfused nephrons was -0.1 +/- 0.2 and 0.0 +/- 0.3 mmHg (NS) in SD and SHR, respectively. In both strains, interaction strength varied inversely with glomerular separation. When the dependence on distance was taken into account, interaction strength was about threefold greater in SHR than in SD. We conclude that the nephron-nephron interaction is significantly greater in SHR. The dependence of interaction strength on distance separating the glomeruli suggests that the interaction is propagated along the preglomerular vasculature.

Leukemoid reaction resulting from multiple cytokine production in metastatic mucoepidermoid carcinoma with central necrosis

We report a male patient with metastatic high-grade mucoepidermoid carcinoma and associated leukemoid reaction. The patient was transferred to our hospital due to persistent spiking fever, marked granulocytosis, and suspected liver abscess. After thorough bacteriological studies, including cultures of blood and material aspirated from the "liver abscess", no evidence of infection was documented. The patient suffered from persistent spiking fever for more than 4 weeks in spite of empirical antibiotic treatment, and repeated aspiration of the presupposed liver abscess. He underwent exploratory laparotomy for intended surgical evacuation of the liver abscess and bacteriological diagnosis. The operative findings were compatible with metastatic carcinoma with multiple liver and retroperitoneal lymph node involvement and tumor necrosis. The pathology report indicated high-grade mucoepidermoid carcinoma. Immunohistochemistry showed positive staining for interleukin-1 alpha (IL-1 alpha) and IL-6. Elevation of cytokine levels in the necrotic tumor fluid, including IL-1 alpha, IL-6, granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor was confirmed by ELISA test. This case shows that multiple cytokine production from a metastatic tumor and its central necrotic area in the liver can produce a febrile leukemoid reaction mimicking a pyogenic liver abscess.

Compact, magneto-optic Q-switched, neodymium-doped bismuth germinate crystal (Nd:BGO) laser pumped by a laser diode

The magneto-optic Q-switched operation of a neodymium-doped bismuth germinate crystal (Nd:BGO) laser that is end pumped by a cw 500-mW laser diode is reported. The crystal is a new host for Nd lasers. Here it acts as a magneto-optic modulator as well as a laser medium. A pulse energy of 2 µJ with a FWHM of 100 ns has been obtained. The device operates at a repetition rate of 1 kHz, and the fluctuation of the shot-to-shot intensity is less than ±1%.

Quantitative analysis of messenger ribonucleic acid encoding natriuretic peptide receptors in aldosterone-producing adenoma

There exist conflicting data regarding the inhibitory effect of atrial natriuretic peptide on aldosterone production from aldosterone-producing adenoma (APA). Natriuretic peptides mediate their actions through natriuretic peptide receptors (NPRs). Whether or not NPRs are present in the tumors remains controversial. To elucidate this paradox, gene expression of NPRs was examined by Northern blot analysis and competitive polymerase chain reaction in tumorous and non-tumorous portions of APA, and in normal adrenal gland from patients with renal cell carcinoma. The results of Northern blot analysis showed the presence of messenger ribonucleic acid (mRNA) of three NPRs in all adrenal tissues, including APA. The proportional expression of NPR gene transcripts in APA was type A (0.6%), type B (18.7%), and type C (80.7%). The levels, but not the proportions, of type C and possibly type B NPR mRNAs were lower in tumorous and non-tumorous portions of APA compared to those in normal adrenal gland (type C 190.2 +/- 24.5 [means +/- SEM, normal adrenal gland] > 168.1 +/- 20.8 [non-tumorous portion] > 112.2 +/- 15.5 [tumorous portion] pg/10 micrograms total RNA, F = 3.82, P < 0.05; type B 45.2 +/- 8.5 [normal adrenal gland] > 30.0 +/- 5.2 [non-tumorous portion] > 25.1 +/- 4.1 [tumorous portion] pg/10 micrograms total RNA, F = 3.03, P = 0.065). The mRNA levels of type C, rather than type A or type B, NPR were correlated with the percentage of zona fasciculata-like cells in APA (r = 0.90, P < 0.05). In conclusion we have demonstrated the presence of mRNA encoding the three NPRs in APA.(ABSTRACT TRUNCATED AT 250 WORDS)

Mathematical modeling of BTX: biotransformation and transport in the subsurface

A two-dimensional compositional model is presented; this model describes the transport and biotransformation of organic contaminants in a variably saturated subsurface environment. Modeled processes included mass exchange between constituent phases (water, air, soil, and organisms), advective and dispersive fluxes in the water phase, diffusive flux in the air phase, and biotransformation and biomass production in the biophase. In this model, solute transfer across air/water and water/solid interfaces is modeled using equilibrium relationships. Rate-limited mass transfer between the water and biophases is described with a linear driving force expression. Microbial degradation and biomass net growth are modeled by Monod-type kinetics. Solute transport and microbial growth equations are solved using an iterative Galerkin finite element method with a variable time-weighting scheme. Coupled biophase mass balance equations for each component are solved with a Newton-Raphson iterative scheme. Model capabilities are illustrated with two-dimensional, cross-sectional simulations of natural bioattenuation. The influence of biotransformation processes on the transport and extent of a toluene plume is examined.

Elevation of serum interleukin-6 levels before peak of serum granulocyte colony-stimulating factor level in chemotherapy-induced myelosuppressive patients

The aim of this study was to ascertain whether any cytokines that function in earlier stages of hematopoiesis also fluctuate in conjunction with granulocyte colony-stimulating factor (G-CSF) in chemotherapy-induced myelosuppression. A total of seven patients were studied. All patients received 3 days of intravenous injection of combination chemotherapy. Patients' absolute neutrophil count (ANC), platelet count, serum G-CSF, interleukin-6 (IL-6), IL-3, and IL-1 alpha were monitored before chemotherapy, and then daily or every other day thereafter during the entire treatment course until the ANC returned to normal. The results showed very obvious elevation of serum IL-6 level before or concurrent with the elevation of serum G-CSF levels at the neutrophil nadir in all seven patients. The rise of IL-6 also correlated with nadir platelet levels in six of seven patients. The finding of serum IL-6 elevation was statistically significant both in neutropenic and thrombocytopenic stages. Serum IL-3 level was below minimum detectable concentrations in all seven patients. Serum IL-1 alpha was below minimum detectable concentration in six patients and demonstrated no obvious fluctuation in the remaining patient. Therefore, the present study demonstrated the chronological time sequence of cytokine fluctuation, IL-6 peak before G-CSF, in chemotherapy-induced myelosuppression. According to this finding, when cytokines are used for prevention of myelosuppression or for acceleration of its recovery, it may be logical to use a combination of cytokines in sequence, such as IL-6 initially followed by G-CSF.

Melatonin and cortisol assessment of circadian shifts in astronauts before flight

Melatonin and cortisol were measured in saliva and urine samples to assess the effectiveness of a 7-day protocol combining bright-light exposure with sleep shifting in eliciting a 12-hr phase-shift delay in eight U.S. Space Shuttle astronauts before launch. Baseline acrophases for 15 control subjects with normal sleep-wake cycles were as follows: cortisol (saliva) at 0700 (0730 in urine); melatonin (saliva) at 0130 (6-hydroxymelatonin sulfate at 0230 in urine). Acrophases of the astronaut group fell within 2.5 hr of these values before the treatment protocols were begun. During the bright-light and sleep-shifting treatments, both absolute melatonin production and melatonin rhythmicity were diminished during the first 3 treatment days; total daily cortisol levels remained constant throughout the treatment. By the fourth to sixth day of the 7-day protocol, seven of the eight crew members showed phase delays in all four measures that fell within 2 hr of the expected 11- to 12-hr shift. Although cortisol and melatonin rhythms each corresponded with the phase shift, the rhythms in these two hormones did not correspond with each other during the transition.

Superior vena cava syndrome revisited

A clinical review with analysis of prognostic factors, including the impact of the initial management modality, was conducted on 137 patients with superior vena cava syndrome (SVCS) seen at the Veterans General Hospital-Taipei between 1989 and 1993. Malignant diseases account for most of the SVCS in our Chinese patients. Patients received diagnostic intervention for their underlying diseases without obvious complications. Whether or not there is a development of SVCS in lung cancer patients, showed prognostic significance in non-small cell lung cancer (NSCLC) and no significance in small cell lung cancer (SCLC). Those with SVCS as the initial manifestation of malignant disease had a poor prognosis compared to those who developed SVCS later. Survival is best in lymphoma/leukemia patients, followed by malignant thymoma and SCLC, and worst in NSCLC and metastatic cancer. The rapid onset of symptoms from SVCS had a short median survival in lung cancer and significantly compromised survival in SCLC. The overall survival of SCLC with SVCS was not affected, regardless of whether the initial therapy had been radiotherapy or chemotherapy.

Zona fasciculata-like cells determine the response of plasma aldosterone to metoclopramide and aldosterone synthase messenger ribonucleic acid level in aldosterone-producing adenoma

The different responses of plasma aldosterone to ACTH and angiotensin II in aldosterone-producing adenoma (APA) is thought to be due to the various cellular compositions of the tumors. To investigate whether the dopaminergic regulation of aldosterone in APA is also dependent on the cellular types, we studied the effects of metoclopramide on plasma aldosterone in six patients with APA. The messenger RNA (mRNA) levels of aldosterone synthase (P450aldo), 11 beta-hydroxylase (P450(11) beta), and 17 alpha-hydroxylase (P450(17) alpha) of APA and normal adrenal glands were determined by competitive polymerase chain reaction. After administration of metoclopramide (an antagonist of dopamine-2 receptor), the increment of plasma aldosterone correlated inversely with the percentage of zona fasciculata cells of APA. The mRNA level of P450aldo in the tumorous portion was much higher, whereas the levels of P450(11) beta and P450(17) alpha mRNAs were lower, than those of the nontumorous portion and normal adrenals. There was a correlation of the percentage of zona fasciculata cells in APA with the levels of P450aldo and P450(11) beta mRNAs, but not with P450(17) alpha mRNA. These results suggest that differential responsiveness of plasma aldosterone to metoclopramide may be due to various proportions of different cell types in APA that may have different expression of dopamine-2 receptor. In addition, this histologically dependent expression was present at the transcriptional level of the gene responsible for aldosterone biosynthesis.

Abdominal tuberculosis in Taiwan: a report from Veterans' General Hospital, Taipei

SETTING

From 1986 to 1992, 27 cases of abdominal tuberculosis were diagnosed in Veterans General Hospital-Taipei, Taiwan, including 21 cases of intestinal tuberculosis and 6 cases of peritoneal tuberculosis.

OBJECTIVE

To ascertain the clinical characteristics of abdominal tuberculosis in Chinese patients and the possibility of early clinical diagnosis of abdominal tuberculosis.

DESIGN

Clinical features, diagnosis and treatment modality of these 27 cases were reviewed.

RESULTS

22 of the patients (81.5%) had chest X-ray evidence of pulmonary tuberculosis. Only 2 had normal chest X-ray findings. Sputum mycobacterium culture was positive in 14 of 27 patients (51.9%). 20 patients received exploratory laparotomy for the diagnosis and all of the preoperative diagnoses were wrong. The diagnosis was still incorrect or uncertain in 9 cases after laparotomy if no pathological examination was done. Ileocecal area was the most common site of intestinal tuberculosis in our series and 3 of 11 ulcerative types of intestinal tuberculosis died later.

CONCLUSION

Due to protean manifestations, the diagnosis of abdominal tuberculosis was frequently misdiagnosed, and particularly as carcinomatosis. The diagnosis should be considered when patients with pulmonary tuberculosis suffer from abdominal discomfort. Exploratory laparotomy is needed in cases suspected of abdominal carcinomatosis without definite diagnosis.

Metastatic nasopharyngeal carcinoma with epidural spinal cord compression: report of an unusual and catastrophic event

Nasopharyngeal carcinoma (NPC) with epidural metastasis of spinal cord has rarely been reported. We present an NPC patient with epidural spinal cord compression due to metastasis. In spite of emergent radiotherapy and large dose decadron treatment, this patient still had severe sequela of paraplegia and incontinence. The epidemiology, clinical findings, diagnosis, treatment and outcome of this metastatic epidural tumor compression were discussed.

Disintegrin modulates rat glomerular mesangial cell behavior

Disintegrins are a group of molecules containing Arg-Gly-Asp (RGD) sequence which can interfere with cell-matrix interaction. Rat mesangial cells are known to express an RGD-sensitive integrin receptor. We investigate the effect of a potent disintegrin, triflavin, on rat mesangial cell adhesion and proliferation. While synthetic RGD-containing peptide (GRGDS) inhibits mesangial cell adhesion to fibronectin, type I and type III collagen, triflavin has a similar but much more potent effect. Triflavin, when added to the medium, inhibits serum-stimulated rat mesangial cell proliferation in both growing and growth-arrested cells. In serum-free medium, platelet-derived growth factor promoted mesangial cell growth is also inhibited by triflavin. When coated as a substratum, both GRGDS and triflavin inhibit mesangial cell growth. The inhibition of proliferation by exogenously added triflavin and GRGDS is, at least in part, due to their antiadhesive effect. We conclude that triflavin can modulate both adhesion and proliferation of rat mesangial cells.

Vasodilator agents modulate rat glomerular mesangial cell growth and collagen synthesis

Mesangial cell activation and extracellular matrix accumulation are hallmarks of many forms of glomerulonephropathy. We investigated the effect of several agents possessing vasodilating activities on rat mesangial cell growth and collagen synthesis. Using cell counting and a modified MTT assay, it was shown that dipyridamole, pentoxifylline, dicentrine, prazosin and doxazosin all caused a dose-dependent inhibition of serum-stimulated rat mesangial cell proliferation. Platelet-derived growth factor-induced cell proliferation was also inhibited by doxazosin and pentoxifylline. Dipyridamole and pentoxifylline inhibited collagen synthesis in confluent mesangial cells while dicentrine and doxazosin did not. The procollagen alpha 1 (I) mRNA expression was also decreased by dipyridamole and pentoxifylline. These results suggested that, in addition to dipyridamole, pentoxifylline and alpha 1-adrenoceptor blockers may have a potential to delay the progression of chronic glomerulopathy associated with mesangial proliferation.

Oligomerization of the HIV type 2 Nef protein: mutational analysis of the heptad leucine repeat motif and cysteine residues

The human immunodeficiency virus type 2 (HIV-2) Nef protein expressed in Escherichia coli forms highly stable homooligomeric complexes in vitro. Similarly, the native protein synthesized in the persistently infected H9 T cell line also forms stable homooligomers in vivo. To determine whether homooligomer formation is mediated by the leucine zipper-type sequence located in the middle region of the protein, site-directed mutagenesis was used to introduce double and triple point mutations at heptad leucine positions L1, L2, and L4 within the HIV-2NIHZ Nef protein sequence. Here, we show that substitution of a serine residue for the L1 (residue 108) and L2 (residue 115) heptad leucines, and a glutamine residue for the L4 (residue 129) heptad leucine, did not prevent Nef homooligomer formation in vitro. However, a more drastic substitution of alpha-helix-breaking proline residue for the L2 and L4 heptad leucines significantly abrogated ability of the protein to form stable homooligomers. In addition, because significantly higher levels of the Nef oligomers were consistently observed under the nonreducing SDS-PAGE condition, site-specific mutagenesis was also used to examine the role of cysteine residues in generating disulfide-linked Nef dimers in vitro. Here, we also show that single cysteine-to-glycine substitutions at positions 28, 32, or 55 drastically reduced covalent Nef dimer formation and thermal stability of the Nef protein in vitro. Therefore, these results demonstrate that the leucine zipper-type motif in the HIV-2 Nef protein mediates stable homooligomer formation in vitro, and also establish a role for covalent disulfide bonds in the formation of linked Nef dimers and thermal stability of the monomer Nef in vitro.

Construction of Tn917ac1, a transposon useful for mutagenesis and cloning of Bacillus subtilis genes

A Tn917 derivative was constructed for the purposes of mutagenesis and cloning of Bacillus subtilis genes. This transposon, Tn917ac1 (4.6 kb), consisted of terminal inverted repeats of Tn917, the res sequence, a ColE1 origin of replication (ori) and two drug-resistance genes. The plasmid carrying this transposon, named pD917, contained the erm-tnpR-tnpA gene cluster of Tn917 and a temperature-sensitive ori of pE194. For the purpose of mutagenesis, transposition of Tn917ac1 was induced by culturing strains harboring pD917 in a medium containing a low concentration of erythromycin. Cells with a Tn917ac1 insertion in the chromosome were selected on agar containing chloramphenicol after heat treatment to eliminate the plasmidic form of pD917. DNA fragments adjacent to Tn917ac1 could be cloned by restriction digestion of the chromosomal DNA and by transforming the self-ligated restriction fragments into Escherichia coli. Sequence analysis revealed that Tn917ac1 was integrated into the chromosome of B. subtilis by transposition in a recE strain and by transposition or integration of pD917 in a wild-type strain. Tn917ac1 has been demonstrated to be useful for mutating and cloning of the genes involved in the biosynthesis of fengycin in B. subtilis F29-3.