Inhibition by vitamin C of DNA adduct formation and arylamine N-acetyltransferase activity in human bladder tumor cells

Previous studies have already demonstrated the protective role of vitamin C (ascorbic acid) in certain types of cancer. This study reports on the effects of vitamin C on arylamine N-acetyltransferase (NAT) activity and DNA adduct formation in a human bladder tumor cell (T24) line. The activity of NAT was measured using high-performance liquid chromatography (HPLC), by assaying for the amounts of acetylated 2-aminofluorene (AF) and p-aminobenzoic acid (PABA) and the remaining amounts of AF and PABA. T24 cells were used for examining NAT activity and carcinogen DNA adduct formation. The results demonstrated that NAT activity and 2-aminofluorene DNA adduct formation in T24 cells were inhibited and decreased by vitamin C in a dose-dependent manner. The apparent kinetic parameters (apparent values of Km and Vmax) from T24 cells were also determined with and without vitamin C cotreatment. The data also indicated that vitamin C decreased the apparent values of Km and Vmax from T24 cells.

Transrectal ultrasonographic findings in patients with hemospermia

BACKGROUND

Hemospermia causes anxiety in many men. Its etiology includes inflammatory disorders, vascular lesions, malignancies and congenital anomalies. With the advent of modern transrectal ultrasonography (TRUS) and magnetic resonance imaging technology, we can now visualize the internal structures of the seminal vesicles and prostate, and identify a more accurate etiology for hemospermia. This study was performed to assess the efficacy of TRUS in the evaluation of hemospermia.

METHODS

TRUS was used to evaluate 40 patients with hemospermia. Patients' ages ranged from 20 to 72 years, with an average age of 41 years. The duration of symptoms was 3 days to 10 years, (average age 12.4 months). Apart from three patients with hepatitis, there was no major illness found in the medical histories. TRUS was performed with a B & K, type 3535 transrectal transducer device, with an 1850 multiplane probe.

RESULTS

TRUS revealed abnormalities in 33 (83%) of 40 patients, which included ejaculatory duct cysts, müllerian duct cysts, asymmetric seminal vesicle dilatation, preprostatic vein engorgement and prostatic enlargement. There were stones in the ejaculatory ducts, ejaculatory duct cysts, müllerian duct cysts or prostate. Nine patients with prostatic stones were under 40 years-of-age. Other than the development of stones, there were no significant differences between patients less than 40 years-of-age and those more than 40 years old.

CONCLUSIONS

The results suggest that TRUS is an effective method for examining the seminal vesicles, ejaculatory duct and prostate complex. Sonoguided aspiration, injection of contrast medium or biopsy can further help to differentiate the nature of hemospermia.

Effects of the butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) on the arylamines N-acetyltransferase activity in rat white blood cells

Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) were used to determine any effects on the N-acetyltransferase (NAT) activity in rat whole blood and white blood cells as measured by high performance liquid chromatography assay for the amounts of N-acetyl-2-aminofluorene (AAF) and 2-aminofluorene (AF). Two assay systems were performed, one with cellular cytosols, the other with intact white blood cells. The NAT activity in the whole blood and white blood cell cytosols was suppressed by BHA and BHT in a dose-dependent manner, i.e. the higher the concentrations of BHA and BHT, the higher the inhibition of NAT activity. Time-course experiments showed that NAT activity measured from the intact white blood cells was inhibited by BHA and BHT up to 24 h. The results suggest that BHA and BHT suppressed AF acetylation in rat blood with intact white blood cells.

Age-dependent increase in C7-1 gene expression in rat frontal cortex

We have previously reported that a fragment of mRNA, denoted as C7-1, which expression was significantly increased in the frontal cortex of aged rats. In the present study, we have cloned and sequenced the full length cDNA of the C7-1 gene. We have found that the open reading frame of this gene encoded a 463-amino-acid protein, which shared 84% identity in amino acid sequence with a subunit of vacuolar H(+)-ATPase (V-ATPase). Further Northern blot analysis revealed that there was an age-dependent increase in C7-1 gene expression in rat frontal cortex, but not in other brain areas. Moreover, application of C7-1 antisense oligonucleotide to cortical neuronal cultures markedly inhibited cell survival. These results together suggest that C7-1 is a marker for the aging process and that upregulation of C7-1 may be important in maintaining the normal function of V-ATPase during aging.

Effects of aspirin on arylamine N -acetyltransferase activity and DNA adducts in human bladder tumour cells

Aspirin (acetylsalicylic acid) was used to determine the inhibition of arylamine N-acetyltransferase (NAT) activity and DNA adduct formation in a human bladder tumour cell line (T24). The activity of NAT was measured by high-performance liquid chromatography, assaying for the amounts of N-acetyl-2-aminofluorene and N-acetyl-p-aminobenzoic acid and remaining 2-aminofluorene and p-aminobenzoic acid. Two assay systems were used: one with cytosol and the other with intact cells. High-performance liquid chromatography was also used to analyse for the 2-aminofluorene-DNA adducts. Intact bladder tumour cells were used. The results demonstrated that NAT activity and 2-aminofluorene-DNA adduct formation in human bladder tumour cells were inhibited by acetylsalicylic acid in a dose-dependent manner. The effects of acetylsalicylic acid on the values of the apparent K(m) and V(max) were also determined in both examined systems. The data also indicated that acetylsalicylic acid decreased the apparent values of K(m) and V(max) from human bladder tumour cells in both cytosol and intact cells.

Identification and characterization of a new lipoprotein, NlpI, in Escherichia coli K-12

We report here the identification of a new lipoprotein, NlpI, in Escherichia coli K-12. The NlpI structural gene (nlpI) is located between the genes pnp (polynucleotide phosphorylase) and deaD (RNA helicase) at 71 min on the E. coli chromosome. The nlpI gene encodes a putative polypeptide of approximately 34 kDa, and multiple lines of evidence clearly demonstrate that NlpI is indeed a lipoprotein. An nlpI::cm mutation rendered growth of the cells osmotically sensitive, and incubation of the insertion mutant at an elevated temperature resulted in the formation of filaments. The altered phenotype of the mutant was a direct consequence of the mutation in nlpI, since it was complemented by the wild-type nlpI gene alone. Overexpression of the unaltered nlpI gene in wild-type cells resulted in the loss of the rod morphology and the formation of single prolate ellipsoids and pairs of prolate ellipsoids joined by partial constrictions. NlpI may be important for an as-yet-undefined step in the overall process of cell division.

A patient with bilateral primary adrenal lymphoma, presenting with fever of unknown origin and achieving long-term disease-free survival after resection and chemotherapy

Primary adrenal lymphoma is extremely rare. We describe a 64-year-old female patient who presented with fever of unknown origin. Imaging studies demonstrated bilateral bulky adrenal masses. She underwent bilateral adrenalectomy and the pathological diagnosis was large cell immunoblastic (B-cell) lymphoma. She received adjuvant combination chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisolone in the following 6 months. She has been relapse free for 52 months. To the best of our knowledge, this case has the longest disease-free survival among those reported. The present case indicated that primary adrenal lymphoma should be included in the differential diagnosis of fever of unknown origin and/or suprarenal mass. Chemotherapy following surgical resection may be considered the treatment of choice.

Transient absorption changes in vivo during photodynamic therapy with pulsed-laser light

High intensity pulsed-laser light can be used to excite absorbing molecules to transient states in large proportions. The laser-induced spectral changes can be characterized by transient changes in light propagation; through the tissue provided the excited states of these molecules have altered absorption spectra. Characterization of these transient changes may then be used to exploit new mechanisms in photosensitization and/or to optimize photobiological effects. In this study, transmittance and reflectance were measured as a function of laser pulse energy, from tissue-simulating media as well as in rat muscle and liver slices, both with and without the photosensitizer benzoporphyrin derivative monoacid (BPD-MA) present. There was a transient decrease in absorption from the photosensitizer at peak pulse irradiance in the range of 100-1000 W cm(-2). The depth of photodynamic treatment-induced tissue necrosis was measured in a subcutaneous prostate cancer model in Copenhagen rats. A comparison between continuous wave irradiation and pulsed irradiation with the same average incident irradiance showed no statistically significant difference in the depth of necrosis at 48 h after irradiation. These results indicate that photosensitizer population-state changes are measurable in tissues and may provide a method for measuring triplet-state properties of photosensitizer in vivo, but for BPD-MA at clinically used concentrations these changes do not significantly affect the depth of photodynamically-induced tissue damage.

Cryopreservation of sperm from the endangered formosan landlocked salmon (Oncorhynchus masou formosanus)

The Formosan landlocked salmon (Oncorhynchus masou formosanus) are at a high risk of extinction, and the sustained maintenance of the population will soon depend on aquaculture systems, which use cryopreservation of spermatozoa to increase genetic diversity. We investigated the effectiveness of dimethyl sulfoxide (DMSO), dimethyl-acetamide (DMA), and methanol as cryoprotectants in combination with 300 mM glucose as extender on the freezing of Formosan landlocked salmon spermatozoa. We also evaluated the morphological changes of Formosan landlocked salmon spermatozoa after their immediate dilution in the 300 mM glucose-DMSO extender and after freeze-thawing. The spermatozoa frozen with DMSO as a cryoprotectant showed significantly higher post-thaw motility and fertility than spermatozoa frozen with DMA or methanol. The fertilization capacity of frozen-thawed Formosan landlocked salmon was comparable to that of fresh spermatozoa. Intersubspecies fertilization trials between cryopreserved Formosan landlocked salmon spermatozoa and Amago salmon eggs showed high fertilization rates. Based on the findings, the potential value of using sperm bank to safeguard this endangered species is discussed.

Photodynamic therapy of orthotopic prostate cancer with benzoporphyrin derivative: local control and distant metastasis

This is the first report of photodynamic therapy (PDT) in an orthotopic prostate tumor model and shows that PDT combined with surgery (tumor bed sterilization) gave significant local control of the primary tumor and significant reduction in distant metastases. By contrast, either treatment alone (surgery or PDT) gave relatively poorer local control, and PDT gave a significant increase in the mean number of lung metastases. The MatLyLu variant of the Dunning 3327 rat prostate cancer cell line, which has been selected to be metastatic to lymph nodes and lungs, was injected into the ventral lobe of the rat prostate. After 7 days, tumors were either treated by surgical removal of the ventral lobe, PDT with liposomal benzoporphyrin derivative monoacid ring A, or a combination of surgery, followed by PDT of the tumor bed. Results after 21 days showed a reduction in prostate tumor weight in all groups compared with controls, which became highly significant only for the combination group (17% of control mean tumor weight; P < 0.001; 7 of 13 clinical complete responses). The combination treatment also led to a reduction in lymph node metastasis and reductions in both the frequency and mean number of lung metastases compared with other treatment groups. The PDT-alone group, however, had a mean number of lung metastases per animal, which was nine times the control group and 34 times the combination group. These findings suggest that a tumor bed sterilization approach may be promising for locally advanced prostate cancer and suggest that factors other than local control may need to be evaluated when considering PDT for primary prostate cancer.

G protein beta subunit is closely associated with microtubules

Previously, we have identified the association of G protein beta subunit (Gbeta) with mitotic spindles in various mammalian cells. Since microtubules are the main component of mitotic spindles, here we have isolated bovine brain microtubules and purified Gbeta subunit to identify the close association of Gbeta subunit with purified brain microtubules and have shown the direct incorporation of Gbeta subunit into the microtubules both in vitro and in vivo. It was found that: (1) microtubular fraction isolated from bovine brain contained Gbeta subunit, (2) coimmunoprecipitation demonstrated that Gbeta subunit could be coprecipitated with tubulin, (3) addition of purified Gbeta subunit into cytosolic extract for microtubule assembly caused direct incorporation of Gbeta subunit into assembled microtubules and increased the association of microtubule-associated proteins with microtubules, and (4) incubation of exogenous Gbeta subunit with detergent-permeabilized cells resulted in direct incorporation of Gbeta subunit into microtubule fibers and depolymerized tubulin molecules. We conclude that G protein beta subunit is closely associated with microtubules and may play an important role in the regulation of microtubule formation in addition to its regulatory role in cellular signal transduction.

Inhibition of the cytotoxicity of protein toxins by a novel plant metabolite, mansonone-D

We have studied the effect of several structurally related mansonones on the cytotoxicity of plant and bacterial toxins in Vero and BER-40, a brefeldin A-resistant mutant of Vero cells. Mansonone-D (MD), a sesquiterpenoid ortho-naphthoquinone, inhibited the cytotoxicity of ricin, modeccin, Pseudomonas toxin, and diphtheria toxin in Vero cells to different extents. The inhibition of ricin cytotoxicity was dose dependent and reversed upon removal of the drug. Protection of ricin cytotoxicity was also observed in the presence of cycloheximide, indicating that de novo protein synthesis is not required for the protective effect. Although MD inhibited the degradation and excretion of ricin, the binding and internalization of ricin was not affected. In contrast, MD strongly reduced the specific binding of diphtheria toxin in Vero cells. Fluorescence microscopic studies show that MD treatment dramatically alters the morphology of the Golgi apparatus in Vero cells. The kinetic studies reveal that the protection of ricin cytotoxicity is the consequence of decreased toxin translocation to the cytosol in MD-treated cells. The reactive ortho-quinone moiety of MD is important for the protective effect as thespesone, a para-naphthoquinone with a heterocyclic ring structure identical to that of MD, did not inhibit the cytotoxicity of toxins. Thespone, a dehydromansonone-D, lacking two hydrogens from the heterocyclic dihydrofuran ring of MD, inhibited the cytotoxicity of ricin, but was albeit less potent than MD. Neither mansonone-E nor mansonone-H with reactive ortho-quinone moiety, but with a different heterocyclic structure, had any effect on the cytotoxicity of ricin indicating that the protective effect of MD is specifically related to the overall structure of the metabolite.

Transcription activation by Escherichia coli FNR protein: similarities to, and differences from, the CRP paradigm

During transcription activation at FNR-dependent promoters where the DNA site for FNR overlaps the -35 element, a surface-exposed activating region in the upstream subunit of the FNR dimer interacts with the C-terminal domain of the RNA polymerase alpha subunit. Starting with a cloned fnr gene encoding a defective FNR derivative carrying substitutions in this activating region, we screened a library of random mutations to identify substitutions that restored FNR activity. Activity can be restored by substitutions at residues T118, E47 and K60. The locations of these residues identify three separate surface-exposed regions of FNR that can play a role in transcription activation. These three regions appear to be analogues of Activating Region 1, Activating Region 2 and Activating Region 3 of the cyclic AMP receptor protein, CRP: our results underscore the similarities between FNR and CRP.

Brain-derived neurotrophic factor antisense oligonucleotide impairs memory retention and inhibits long-term potentiation in rats

We have examined the relationship between brain-derived neurotrophic factor gene expression in the hippocampus and memory retention as well as long-term potentiation of rats. One-way inhibitory avoidance learning was adopted as the behavioural paradigm. Results revealed that brain-derived neurotrophic factor messenger RNA levels in the dentate gyrus of the hippocampus were markedly increased at 1 h, 3 h and 6 h post-training in rats showing good retention performance when compared with the poor retention controls. Direct injection of brain-derived neurotrophic factor antisense oligonucleotide into the dentate gyrus of the hippocampus before memory consolidation takes place markedly impaired retention performance in rats. It also significantly decreased brain-derived neurotrophic factor messenger RNA level in the dentate gyrus. The same antisense treatment also markedly reduced the amplitude and slope of excitatory postsynaptic potential as well as the brain-derived neurotrophic factor messenger RNA level in the dentate gyrus. These results suggest that hippocampal brain-derived neurotrophic factor gene expression plays an important role in the memory consolidation process and in the expression of long-term potentiation in rats. These results provide the first evidence to relate brain-derived neurotrophic factor gene expression and memory function in vertebrates. It further suggests that brain-derived neurotrophic factor gene expression is involved in behavioural plasticity.

A Salmonella typhimurium genetic locus which confers copper tolerance on copper-sensitive mutants of Escherichia coli

Three distinct clones from a Salmonella typhimurium genomic library were identified which suppressed the copper-sensitive (Cu(s)) phenotype of cutF mutants of Escherichia coli. One of these clones, pCUTFS2, also increased the copper tolerance of cutA, -C, and -E mutants, as well as that of a lipoprotein diacylglyceryl transferase (lgt) mutant of E. coli. Characterization of pCUTFS2 revealed that the genes responsible for suppression of copper sensitivity (scs) reside on a 4.36-kb DNA fragment located near 25.4 min on the S. typhimurium genome. Sequence analysis of this fragment revealed four open reading frames (ORF120, ORF627, ORF207, and ORF168) that were organized into two operons. One operon consisted of a single gene, scsA (ORF120), whereas the other operon contained the genes scsB (ORF627), scsC (ORF207), and scsD (ORF168). Comparison of the deduced amino acid sequences of the predicted gene products showed that ScsB, ScsC, and ScsD have significant homology to thiol-disulfide interchange proteins (CutA2, DipZ, CycZ, and DsbD) from E. coli and Haemophilus influenzae, to an outer membrane protein (Com1) from Coxiella burnetii, and to thioredoxin and thioredoxin-like proteins, respectively. The two operons were subcloned on compatible plasmids, and complementation analyses indicated that all four proteins are required for the increased copper tolerance of E. coli mutants. In addition, the scs locus also restored lipoprotein modification in lgt mutants of E. coli. Sequence analyses of the S. typhimurium scs genes and adjacent DNAs revealed that the scs locus is flanked by genes with high homology to the cbpA (predicted curved DNA-binding protein) and agp (acid glucose phosphatase) genes of E. coli located at 22.90 min (1,062.07 kb) and 22.95 min (1,064.8 kb) of the E. coli chromosome, respectively. However, examination of the E. coli chromosome revealed that these genes are absent at this locus and no evidence has thus been obtained for the occurrence of the scs locus elsewhere on the genome.

Roles of histidine-103 and tyrosine-235 in the function of the prolipoprotein diacylglyceryl transferase of Escherichia coli

Phosphatidylglycerol:prolipoprotein diacylglyceryl transferase (Lgt) is the first enzyme in the posttranslational sequence of reactions resulting in the lipid modification of lipoproteins in bacteria. A previous comparison of the primary sequences of the Lgt enzymes from phylogenetically distant bacterial species revealed several highly conserved amino acid sequences throughout the molecule; the most extensive of these was the region 103HGGLIG108 in the Escherichia coli Lgt (H.-Y. Qi, K. Sankaran, K. Gan, and H. C. Wu, J. Bacteriol. 177:6820-6824, 1995). These studies also revealed that the kinetics of inactivation of E. coli Lgt with diethylpyrocarbonate were consistent with the modification of a single essential histidine or tyrosine residue. The current study was conducted in an attempt to identify this essential amino acid residue in order to further define structure-function relationships in Lgt. Accordingly, all of the histidine residues and seven of the tyrosine residues of E. coli Lgt were altered by site-directed mutagenesis, and the in vitro activities of the altered enzymes, as well the abilities of the respective mutant lgt alleles to complement the temperature-sensitive phenotype of E. coli SK634 defective in Lgt activity, were determined. The data obtained from these studies, in conjunction with additional chemical inactivation studies, support the conclusion that His-103 is essential for Lgt activity. These studies also indicated that Tyr-235 plays an important role in the function of this enzyme. Although other histidine and tyrosine residues were not found to be essential for Lgt activity, alterations of His-196 resulted in a significant reduction of in vitro activity.

Antisense oligonucleotides to corticotropin-releasing factor impair memory retention and increase exploration in rats

Corticotropin-releasing factor is known as a stress peptide which stimulates adrenocorticotropin and corticosterone release. It also has a direct central effect to produce various behavioural activations in rats. In the present study, we have designed and studied the effects of an antisense oligonucleotide directed against the corticotropin-releasing factor gene in rats. Local injection of this antisense oligonucleotide into the hippocampus (1 nmol, five injections) significantly impaired the retention performance of an inhibitory avoidance task in rats. In another experiment, the same injection (1 nmol, four injections) also markedly increased rearing response and total distance travelled by rats in a novel activity chamber. Meanwhile, it markedly decreased grooming behaviour in rats. When directly injected into the hypothalamus in another group of animals (1 nmol, four injections), this antisense oligonucleotide significantly decreased the plasma adrenocorticotropin level. The effectiveness of these antisense oligonucleotide treatments was verified by a significant reduction in the level of corticotropin-releasing factor messenger RNA in specific brain regions as determined by quantitative reverse transcription polymerase chain reaction analysis. These results strengthen the importance of corticotropin-releasing factor in modulating memory processing and exploratory behaviour in rats. This work also provides an important tool for studying other physiological functions that corticotropin-releasing factor may mediate or modulate in mammals.

The clinical experience of gaseous retroperitoneoscopic and gasless retroperitoneoscopy-assisted unroofing of renal cyst

BACKGROUND

The aim of this study is to compare the application of gaseous retroperitoneoscopic (GR) and gasless retroperitoneoscopy-assisted (GLRA) unroofing of renal cysts.

METHODS

Fourteen patients with symptomatic simple renal cysts had undergone unroofing of the cyst with GR in seven cases and GLRA in seven others. Three trocars (10 mm, 10 mm and 5 mm) were inserted in the GR procedure. A 3 cm flank muscle-split incision was made and retroperitoneoscopy was performed through the same incision in the GLRA procedure. Then, the cyst was unroofed.

RESULTS

The mean operative time was 104.3 minutes in the GR group and 52.1 minutes in the GLRA group, respectively (p = 0.001). The mean requirement of postoperative meperidine hydrochloride injection was 21.4 mg in the GR group and 71.4 mg in the GLRA group, respectively (p = 0.017). In the GR group, the mean postoperative stay was 3.7 days, and the time needed for return to normal activity was 7 days. In the GLRA group, the mean postoperative stay was 4.6 days, and the time needed for return to normal activity was 8 days.

CONCLUSIONS

GR and GLRA techniques for unroofing of renal cysts are safe, effective and minimally invasive. GLRA is easy to perform and a more time-saving procedure when compared to GR, however, the patients of GLRA suffered more postoperative pain than after GR. GLRA is recommended in patients who had received retroperitoneal surgery or who have multiple renal cysts.

Identification of a rat brain gene associated with aging by PCR differential display method

The polymerase chain reaction (PCR) differential display method is a powerful tool to detect and characterize alteration of gene expression in eukaryotic cells. In order to screen the differentially expressed genes between the adult (3 mo) and aged (24 mo) rats, the PCR differential display method was adopted in the present study. One differentially expressed cDNA band (C7-1) was identified and the aged rats expressed more the C7-1 gene than the adult rats in the frontal cortex, but not in the hippocampus and hypothalamus. The C7-1 cDNA band was recovered, reamplified, and subcloned as a probe in Northern blot analysis. A transcript of approx 2.8 kb was expressed in the frontal cortex of both the adult and aged rats, but the C7-1 mRNA level was increased for 52% in the aged rats. The C7-1 gene was then sequenced that contains 243 bp. We have found that the C7-1 cDNA shows no significant homology to any published genes, suggesting that the C7-1 gene is an unknown gene associated with aging. This study provides the first evidence to show that there is alteration in gene expression associated with aging by using the PCR differential display method.

Prognostic factors of primary aldosteronism

BACKGROUND

Primary aldosteronism (PA) is a rare but potentially curable cause of hypertension. Between October 1982 and November 1994, 30 patients of PA received unilateral adrenalectomy with a long-term follow up (mean:60.3 months). Nineteen (63.3%) cases were cured (Group 1); 11(36.7%) cases were improved (Group 2). The purpose of this study was to determine prognostic factors after surgery in patients with PA.

METHODS

A retrospective analysis was performed regarding age and sex of the patients, duration of hypertension, family history of hypertension, preoperative blood pressure, plasma aldosterone concentration (PAC), plasma renin activity (PRA) and efficacy of spironolactone on blood pressure between both groups. End-organs (including kidney, heart, retina and brain) involvement was evaluated and compared. Adrenalectomy and renal biopsy specimen for pathology were similarly evaluated.

RESULTS

The duration of hypertension was longer in Group 2 than in Group 1 (8.18 +/- 4.94 vs 5.21 +/- 4.24 years). The efficacy of spironolactone on blood pressure (BP) was positive in 81.8% of Group 1 and 16.7% of Group 2. Adrenal cortical adenoma in 24 cases with a cure rate of 70.8% (17/24) and adrenal cortical macronodular hyperplasia in 6 cases with a cure rate of 33.3% (2/6) were noted. Group 2 had more end-organs involvement than Group 1. The severity of histopathological change of the renal biopsy was similar.

CONCLUSIONS

This study suggests that preoperative response of blood pressure to spironolactone administration predicts the postoperative prognosis of hypertension in patient with PA. Long duration of hypertension and involvement of two or more end-organs were poor prognostic factors. Excellent results can be achieved by unilateral adrenalectomy in adrenal cortical adenoma and fair results, in adrenal cortical macronodular hyperplasia.

Structure-function relationship of bacterial prolipoprotein diacylglyceryl transferase: functionally significant conserved regions

The structure-function relationship of bacterial prolipoprotein diacylgyceryl transferase (LGT) Has been investigated by a comparison of the primary structures of this enzyme in phylogenetically distant bacterial species, analysis of the sequences of mutant enzymes, and specific chemical modification of the Escherichia coli enzyme. A clone containing the gene for LGT, lgt, of the gram-positive species Staphylococcus aureus was isolated by complementation of the temperature-sensitive lgt mutant of E. coli (strain SK634) defective in LGT activity. In vivo and in vitro assays for prolipoprotein diacylglyceryl modification activity indicated that the complementing clone restored the prolipoprotein modification activity in the mutant strain. Sequence determination of the insert DNA revealed an open reading frame of 837 bp encoding a protein of 279 amino acids with a calculated molecular mass of 31.6 kDa. S. aureus LGT showed 24% identity and 47% similarity with E. coli, Salmonella typhimurium, and Haemophilus influenzae LGT.S. aureus LGT, while 12 amino acids shorter than the E. coli enzyme, had a hydropathic profile and a predicted pI (10.4) similar to those of the E. coli enzyme. Multiple sequence alignment among E. coli, S. typhimurium, H. influenzae, and S. aureus LGT proteins revealed regions of highly conserved amino acid sequences throughout the molecule. Three independent lgt mutant alleles from E. coli SK634, SK635, and SK636 and one lgt allele from S. typhimurium SE5221, all defective in LGT activity at the nonpermissive temperature, were cloned by PCR and sequenced. The mutant alleles were found to contain a single base alteration resulting in the substitution of a conserved amino acid. The longest set of identical amino acids without any gap was H-103-GGLIG-108 in LGT from these four microorganisms. In E. coli lgt mutant SK634, Gly-104 in this region was mutated to Ser, and the mutant organism was temperature sensitive in growth and exhibited low LGT activity in vitro. Diethylpyrocarbonate inactivated the E. coli LGT with a second-order rate constant of 18.6 M-1S-1, and the inactivation of LGT activity was reversed by hydroxylamine at pH 7. The inactivation kinetics were consistent with the modification of a single residue, His or Tyr, essential for LGT activity.