Proliferative responses to PHA, anti-CD3 and antigens in patients with lymphoproliferative disease of granular lymphocytes. Mannoproteins of Candida albicans induce proliferation and cytotoxicity

In this paper we investigated the lymphoproliferative and cytotoxic responses of peripheral blood mononuclear cells (PBMC) of patients affected with lymphoproliferative disease of granular lymphocytes of T cell origin to mitogens and antigens. Most patients with lymphoproliferative disease of granular lymphocytes (LDGL) showed a severely impaired PBMC proliferative capacity in response to phytohemagglutinin, anti-CD3 and tetanus toxoid, an impairment that, in the case of anti-CD3 response, appears to be related to a defect of phosphorylation in response to triggering. In contrast, at least 50% of the patients had normal proliferation in response to a mannoprotein fraction purified from Candida albicans. These data suggest that some CD3+ GL from LDGL patients, that usually respond poorly to proliferative stimuli in vitro, can be triggered to perform these functions by candidal antigens.

Platelet Activation in Hypercholesterolemic Patients Submitted to Therapeutic Plasmapheresis. An Ultrastructural Study

Therapeutic plasmapheresis has been recommended as the choice therapy in patients with familial hypercholesterolemia. Little is known about the effect of plasmapheresis on platelet behavior. By means of electron microscopy we have studied the platelet plasma membrane of 4 patients with familial hypercholesterolemia who were submitted to repeated plasmaphereses. After each procedure of plasmapheresis, at the 15th day, morphometrical studies revealed a statistically significant increase in the surface density of the Open Canalicular System, which is considered a marker of platelet activation. However, during 12 months of plasmapheresis, a significant mean decrease in the morphometric parameters was observed. On one hand, these results indicate the necessity to consider the blood hemocoagulatory state in the patient who has been submitted to the above mentioned treatment, since the variation of these parameters after the therapeutic procedure, in a short time, could be potentially harmful to the patient; on the other hand, these results indicate, for the first time, the ability of the procedure to improve platelet behavior after repeated treatments on long term basis.

[Otoacoustic distortion products in sensorineural hearing loss in the cochlea]

The purpose of the present work was to assess distortion-product otoacoustic emissions (DPOAE) in cochlear hearing loss and in its various morphologies. A total of 19 patients (30 ears) were selected for the study. They showed various pictures of neurosensorial hearing loss which were localized within the frequency range normally examined during audiometric tonal threshold testing. The DPOAEs were recorded using a Bray and Kemp ILO 92 instrument. The DPOAEs of several frequencies (750,1000,1500,2000,3000,4000 and 6000 Hz) were examined using an f2 tone of 696, 1001, 1587, 2002, 3147, 4004 and 6348 Hz, respectively. The results were as follows: a) At certain frequencies the overlap between hearing loss and the absence of, or reduction in, DPOAE amplitude was virtually total. b) There was a modest correlation between the degree of hearing loss and decrease in, or absence of, DPOAEs although there was a spectrum of intermediate hearing losses where the DPOAEs varied widely from one individual to another (this spectrum ranged from 10 to 45 dB HL on the audiometric tonal test). c) The absence of DPOAEs at 750 Hz is unable to predict hearing loss for this frequency as, at this frequency, there can be a lack of DPOAEs even when the 750 Hz audiometric threshold level is normal. Finally, what emerged from this study was that DPOAEs prove quite useful to complement the study of auditory brainstem responses (ABR), now universally accepted as the means for early diagnosis of hearing loss in children. In fact, ABRs provide precise data regarding a frequency field which is socially less important in terms of verbal communication and the development of spoken language. It is, however, unable to explore individual frequencies.

Pravastatin reduces carotid intima-media thickness progression in an asymptomatic hypercholesterolemic mediterranean population: the Carotid Atherosclerosis Italian Ultrasound Study

PURPOSE

The Carotid Atherosclerosis Italian Ultrasound Study (CAIUS) was performed to test the effects of lipid lowering on the progression of carotid intima-media thickness (IMT) in 305 asymptomatic patients from a Mediterranean country.

PATIENTS AND METHODS

Eligibility included hypercholesterolemia (baseline means: low-density lipoprotein [LDL] = 4.68 mmol/L, high-density lipoprotein [HDL] = 1.37 mmol/L), and at least one 1.3 < IMT < 3.5 mm in the carotid arteries. Patients (mean age 55 years, 53% male) were assigned to pravastatin (40 mg/day, n = 151) or placebo (n not equal to 154). Ultrasound imaging was used to quantify IMT at baseline, and semiannually thereafter for up to 3 years. The mean of the 12 maximum IMTs (MMaxIMT), was calculated for each patient visit, and used to determine each patient's longitudinal progression slope. The intention-to-treat group difference in the MMaxIMT progression was chosen a priori as the primary end point.

RESULTS

Five serious cardiovascular events (1 fatal myocardial infarction), and 7 drop-outs for cancer were registered. In the pravastatin group, LDL decreased -0.22 after 3 months versus -0.01 in the placebo group, and remained substantially unchanged afterward (-0.23 versus +0.01 at 36 months, respectively). Progression of the MMaxIMT was 0.009 +/- 0.0027 versus -0.0043 +/- 0.0028 mm/year (mean +/- SE, P < 0.0007) in the placebo and pravastatin groups, respectively. IMT progression slopes diverged after 6 months of treatment.

CONCLUSIONS

Pravastatin stops the progression of carotid IMT in asymptomatic, moderately hypercholesterolemic men and women. This finding extends the beneficial effects of cholesterol lowering to the primary prevention of atherosclerosis in a population with relatively low cardiovascular event rates, and suggests that this benefit is mediated by specific morphological effects on early stages of plaque development.

A clinical/statistical comparison between the subpedicle connective tissue graft method and the guided tissue regeneration technique in root coverage

Subepithelial connective tissue grafts and guided tissue regeneration have been shown to be effective means to obtain root coverage. The purpose of this study is to compare statistically the results obtained with these techniques 1 year after the surgical procedures were performed. Thirty-six gingival recessions belonging to Class I and Class II of the Miller classification were treated: 18 cases with subepithelial connective tissue grafts (SCTG) and 18 cases with guided tissue regeneration (GTR). Each patient was randomly assigned to a group. At baseline, the group treated with subepithelial connective tissue grafts presented a mean recession of 4.88 mm, whereas the group treated with guided tissue regeneration presented a mean recession of 5.88 mm (P = .082). After 1 year, the mean root coverage was 77.08% in the SCTG group and 80.88% in the GTR group. The difference was not statistically significant (P > .05). The mean root coverage was 3.83 mm for the SCTG group and 4.61 mm for the GTR group. The mean gain in probing attachment level was 3.05 mm for the SCTG group and 5.55 mm for the GTR group. The difference was statistically significant (P = .01). In conclusion, the mean root coverage obtained was similar for the two groups, whereas the clinical attachment gain was greater in the GTR group. Therefore, it appears that the GTR technique is preferable when severe mucogingival defects are present and gain of clinical attachment level is mandatory.

HCV infection in a patient with hyper IgM syndrome

The association between an acquired form of hyper-IgM syndrome and a chronic hepatitis C virus (HCV) infection in a 71-year-old female patient is described. Both diseases were diagnosed at the age of 58 years. She was started on intramuscular and then intravenous immunoglobulin replacement therapy. HCV RNA was detected in 1992. The patient remained in well-balanced clinical condition until 1994, when total and specific anti-HCV IgM levels increased and the patient developed an IgM kappa monoclonal gammopathy. Adherent cells and B cells were HCV RNA positive, while T cells were HCV RNA negative. Anti-IgM reactivity was specifically directed to the core antigen of the HCV. The patient we describe showed a picture of a late-onset form of hypogammaglobulinemia with a progressive increase in IgM antibodies, possibly due to the concomitant HCV infection. It is possible that the immunodeficiency might also result from the HCV infection, with formation of specific antibodies belonging to the IgM class, and that the worsening of the clinical condition may be directly related to the persistent viral infection.

Structural flexibility modulates the activity of human glutathione transferase P1-1. Role of helix 2 flexibility in the catalytic mechanism

Presteady-state and steady-state kinetic studies performed on human glutathione transferase P1-1 (EC 2.5.1.18) with 1-chloro-2, 4-dinitrobenzene as co-substrate indicate that the rate-determining step is a physical event that occurs after binding of the two substrates and before the final sigma-complex formation. It may be a structural transition involving the ternary complex. This event can be related to diffusion-controlled motions of protein portions as kcat degrees /kcat linearly increases by raising the relative viscosity of the solution. Similar viscosity dependence has been observed for Km GSH, while Km CDNB is independent. No change of the enzyme structure by viscosogen has been found by circular dichroism analysis. Thus, kcat and Km GSH seem to be related to the frequency and extent of enzyme structural motions modulated by viscosity. Interestingly, the reactivity of Cys-47 which can act as a probe for the flexibility of helix 2 is also modulated by viscosity. Its viscosity dependence parallels that observed for kcat and Km GSH, thereby suggesting a possible correlation between kcat, Km GSH, and diffusion-controlled motion of helix 2. The viscosity effect on the kinetic parameters of C47S and C47S/C101S mutants confirms the involvement of helix 2 motions in the modulation of Km GSH, whereas a similar role on kcat cannot be ascertained unequivocally. The flexibility of helix 2 modulates also the homotropic behavior of GSH in these mutants. Furthermore, fluorescence experiments support a structural motion of about 4 A occurring between helix 2 and helix 4 when GSH binds to the G-site.

Structural flexibility modulates the activity of human glutathione transferase P1-1. Influence of a poor co-substrate on dynamics and kinetics of human glutathione transferase

Presteady-state and steady-state kinetics of human glutathione transferase P1-1 (EC 2.5.1.18) have been studied at pH 5.0 by using 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, a poor co-substrate for this isoenzyme. Steady-state kinetics fits well with the simplest rapid equilibrium random sequential bi-bi mechanism and reveals a strong intrasubunit synergistic modulation between the GSH-binding site (G-site) and the hydrophobic binding site for the co-substrate (H-site); the affinity of the G-site for GSH increases about 30 times at saturating co-substrate and vice versa. Presteady-state experiments and thermodynamic data indicate that the rate-limiting step is a physical event and, probably, a structural transition of the ternary complex. Similar to that observed with 1-chloro-2, 4-dinitrobenzene (Ricci, G., Caccuri, A. M., Lo Bello, M., Rosato, N. , Mei, G., Nicotra, M., Chiessi, E., Mazzetti, A. P., and Federici, G.(1996) J. Biol. Chem. 271, 16187-16192), this event may be related to the frequency of enzyme motions. The observed low, viscosity-independent kcat value suggests that these motions are slow and diffusion-independent for an increased internal viscosity. In fact, molecular modeling suggests that the hydroxyl group of Tyr-108, which resides in helix 4, may be in hydrogen bonding distance of the oxygen atom of this new substrate, thus yielding a less flexible H-site. This effect might be transmitted to the G-site via helix 4. In addition, a new homotropic behavior exhibited by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole is found in Cys-47 mutants revealing a structural intersubunit communication between the two H-sites.

Primary sclerosing cholangitis: clinical presentation, natural history and prognostic variables: an Italian multicentre study. The Italian PSC Study Group

OBJECTIVE

Because large-scale reports of PSC in the Mediterranean area we are still lacking, in this study we evaluated by Kaplan-Meyer analysis the natural history of primary sclerosing cholangitis (PSC) in Italy and by means of other statistical methods we identified the variables most useful in predicting survival of such patients.

DESIGN

Retrospective multicentre study of unselected patients with PSC. Several variables involving sex, age, associated diseases, clinical features, laboratory, cholangiographic and histological findings at presentation and clinical outcome at data recording were collected by means of a detailed questionnaire.

SETTING

16 Italian university and regional hospitals all over the country, thus giving a geographically representative population.

PATIENTS

A total of 117 PSC patients (73 men and 44 women); median age 35 years.

METHODS

Survival analysis was performed by the Kaplan-Meyer method; the prognostic influence on survival of collected data was evaluated by univariate chi(2) analysis with Wilcoxon and log-rank tests. The same prognostic variables were also evaluated by multivariate analysis (Cox model), using a stepwise regression procedure. All statistical analyses were performed using the SAS statistical software.

RESULTS

At presentation 70% of patients were symptomatic; symptoms did not relate to liver histology. Both intra- and extrahepatic bile duct lesions were detected in 46% of patients at cholangiography. Inflammatory bowel disease was found in 54% of symptomatic patients, ulcerative colitis was 36% of total. Clinical outcome (91/117): 15 underwent liver transplantation or died from liver disease (cholangiocarcinoma). Survival at 10 years was 74%. Features of poor prognosis were cholesterol, aspartate aminotransferase (AST), haemoglobin and albumin.

CONCLUSION

PSC in Italy mainly follows a benign course and among clinical features recorded at presentation, serum cholesterol, AST, haemoglobin and albumin may provide some objective criteria to assess disease severity.

In vitro permeability evaluation and colonization of membranes for periodontal regeneration by Porphyromonas gingivalis

The use of membranes for periodontal regeneration is well established. In clinical use, the exposure of membranes to the oral microflora may result in a pathway for periodontal infections. An important role in this process is played by Porphyromonas gingivalis. The purpose of the present study was to examine the colonization of 6 different bioresorbable and nonresorbable membranes for periodontal regeneration by the strain DSM 20709 of P. gingivalis and to determine the time needed by this microorganism to pass through the membranes. A device consisting of a tube sealed with the membranes and filled with a medium suitable for the growth of P. gingivalis was incubated in a bigger tube containing the same medium to study the process of colonization and the crossing of membranes. The outer tube was inoculated with 10(4) cells of P. gingivalis DSM 20709. The passage of bacteria through the membranes was monitored at 6, 24, and 48 hours by counting the number of cells in the inner tube. The colonized membranes were observed using a scanning electron microscope. Differences in the behavior of the 6 membranes analyzed were demonstrated.

[Maternal-fetal transmission of human papillomavirus]

AIM

Human papilloma virus (HPV) infection is one of the most frequently observed sexually-transmitted diseases (10-60% of the general population). In pregnant women, as well as accelerating the evolution of dysplasia to cervical cancer, the infection may be transmitted to the fetus during gestation or at the time of birth. Children who have been infected at birth may develop laryngeal papillomatosis during the first 5 years of life that may, in some cases, spread to the point of causing aphonia or severe respiratory obstruction. There is also the risk, although it is very low, of a carcinomatous degeneration of the larynx in these subjects during adulthood. The hypothesis of the present study was to verify the prevalence of HPV infection in a population of pregnant women and the prevalence of maternal-fetal transmission.

EXPERIMENTAL DESIGN

A prospective longitudinal design lasting 11 months was used for the study. It included the collection of an endocervical biopsy from population of pregnant women using a swab that was diluted in 3 cc of physiological solution, and the collection of oropharyngeal secretions from their respective neonates using a cottonwool bud.

PARTICIPANTS AND METHODS

A total of 170 pregnant women attending the Obstetric Centre of the Obstetric and Gynecological Clinic of Trieste University were recruited in the study. An endocervical biopsy was taken during the 1st and/or 2nd trimester of gestation and/or at the start of labour. Of these subjects, 23 completed all the planned biopsies and a sample of oropharyngeal secretion was collected from their neonates.

TESTS

From the material obtained the presence of HPV-DNA was analysed using a PCR (protein chain reaction) technique consisting of the following steps: 1) culture of human cells expressing sequences of HPV 16 and 18 used as positive controls; 2) preservation of tissue material washed in watery 4% formalin solution; 3) amplification and viral characterization in types 6-11-16-18-31-33-52.

RESULTS

Positive HPV-DNA results in at least one of the three samples collected during the various periods of gestation was 31.2%, whilst in the population in which all the planned samples were performed the frequency of positive cases was 30.4%. Positive results for HPV-DNA in oropharyngeal secretions from neonates was 21.7%. The concordance of positivity for HPV-DNA in mothers at the time of labour and in their respective neonates was 57.14%.

CONCLUSIONS

The trend of infection did not reveal substantial changes during the various gestational periods in which tests were performed. The possibility of HPV-DNA transmission from mother to fetus is high, above all when the maternal PCR test is positive at the time of birth, or in the presence of a high viral load. This justifies the need to monitor this infection in pregnancy in those affected by florid genital condylomatosis or with koilocytosis on cervical cytology. It is also appropriate to check all HPV-DNA positive neonates one year after birth.

Gonadal function after multimodality treatment in men with testicular germ cell cancer

We evaluated gonadal function in 63 patients with testicular cancer both within 1 month of unilateral orchiectomy before further treatment (pretreatment) and 3 years after treatment discontinuation (post-treatment). Sixteen patients underwent orchiectomy alone (group 1), nine patients underwent infradiaphragmatic radiotherapy (group 2) and 28 patients received four cycles (group 3) and 10 patients received six cycles (group 4) of cisplatin-based chemotherapy (cisplatin, vinblastine and bleomycin-PVB, or cisplatin, etoposide and bleomycin-PEB). Pretreatment semen analyses showed reduced sperm cell density, motility and impaired morphology of spermatozoa in all four groups (p > 0.05). At the same time elevated estradiol and decreased serum follicle-stimulating hormone (FSH) levels in 28.5% of subjects were correlated with high serum beta human chorionic gonadotropin concentrations. Semen analyses revealed the lowest values for all parameters after infradiaphragmatic radiotherapy. Sperm cell count, motility and morphology were significantly better in patients treated with orchiectomy alone or with a conventional dose of chemotherapy than in the groups that received radiotherapy or high doses of chemotherapy (p < 0.05). We also observed a correlation between serum FSH values and sperm cell density for both pretreatment and post-treatment in every group of patients (p < 0.05). Persistent subclinical Leydig cell dysfunction in groups treated with radiotherapy or high doses of chemotherapy was expressed by increased basal luteinizing hormone levels (78% of patients in group 2 vs 60% of patients in group 4) (p < 0.05) and by normal testosterone serum values (89% of patients in group 2 vs 80% of patients in group 4). Spermatogenesis and Leydig cell function are, therefore, persistently impaired in the majority of testicular cancer patients treated with radiotherapy or with more intensive chemotherapy.

[Products of acoustic distortion in the examination of deafness in an infant]

Distortion-product otoacoustic emissions (DPOAEs) are otoacoustic emissions evoked by two pure tones. The greatest advantage of DPOAEs is their frequency specificity with respect to the eliciting bitonal stimuli. The purpose of this study was to compare DPOAEs in two populations. This paper reports input/output DPOAEs functions and DPOAE-audiograms for audiometric frequencies of f2 between 696 and 6006 Hz in a normal neonate population and in an adult control group. Fifteen healthy fullterm newborns (29 ears) and 8 normal-hearing adults (16 ears) participated as subjects. Results at medium frequencies indicate that the maximum amplitudes of the DPOAEs were generated by neonates, the detection threshold was better and the dynamic range was greater than in adults, making them potentially valid for studying cochlear functioning in infants.

The determination of plasma transferrin receptor as good index of erythropoietic activity in renal anemia and after renal transplantation

Both the plasma determinations of erythropoietic (EPO) and transferrin receptor (TfR) would provide a good characterization of anemia especially when mixed erythron disorders underlie, such as in renal failure. Immunologic assays of EPO and TfR, as well as standard hematologic determinations (hematocrit, reticulocyte count, serum iron, transferrin, ferritin) were performed in patients with chronic renal failure (CRF), in regular dialysis treatment (RDT) and in transplanted (TX) patients. In nonanemic TX patients both EPO and TfR ranged normally, whereas in anemic TX ones (Hct < 40%) both values were increased suggesting the physiologic response both of the kidney and of the erythron to decreased red cell mass. In transitory posttransplant erythrocytosis the increased values of TfR, with normal EPO values, would hypothesize a defective feedback to EPO release. Both EPO and TfR values were found increased in TX patients with adult polycystic kidney disease with persistent erythrocytosis (Hct > 50%), thus confirming previous observations. In CRF and RDT patients, all anemic, both EPO and TfR were normal, even though significantly low with respect to the degree of anemia. In RDT seriously anemic patients, the administration of recombinant human EPO induced different patterns of bone marrow response. We conclude that the determination of TfR would provide further information on renal anemia since the receptor increase mostly preceded the rise of Hct, evidencing those patients who will not have an effective bone marrow response to the therapy.

[Evoked otoacoustic emissions using clicks in detection of deafness in young children]

Click-evoked otoacoustic emissions (EOAEs) are sounds emitted by the cochlea due to active outer hair cell contraction following stimulation of the stereocilia. The purpose of this study was to evaluate the use of testing for EOAEs as a valid auditory screening method in newborns, and 1074 healthy fullterm babies (2148 ears) with an Apgar score higher than 8 at birth were examined. EOAEs were elicited 4 days after birth and a correlation index higher than 70% represented normal response criteria. If there was no response, EOAEs and brainstem response potentials were tested at the age of one month. On the fourth day after birth. EOAEs specificity and efficiency were found to be 92.3% and 92.4% respectively, while sensitivity was 100%. Specificity and efficiency at one month were rated at 100%. The use of EOAEs offers numerous advantages over traditional auditory screening methods, thus suggesting that this technique is suitable for the mass-screening of infants.

Comparison of serum total sialic acid, C-reactive protein, alpha 1-acid glycoprotein and beta 2-microglobulin in patients with non-malignant bowel diseases

Total sialic acid (TSA), C-reactive protein (CRP); alpha 1 acid glycoprotein (alpha 1-AG), and beta 2-microglobulin were determined in 84 patients affected by non-malignant intestinal diseases, Crohn's disease (CD) and ulcerative colitis (UC), active and in remission; non-ulcerative proctosigmoiditis; diverticulosis; diverticulitis (ie, inflammatory complication of diverticulosis). Only in patients with acute phase CD, TSA was statistically higher than those in remission, as well as in controls. In patients with acute CD and in those with diverticulitis, CRP was significantly higher than in the controls. alpha 1-AG was found significantly increased in acute UC and CD patients versus the respective groups in remission, as well as versus controls. Moreover, alpha 1-AG was higher in patients with diverticulitis. beta 2-microglobulin did not differ in any group of patients. In five patients with CD in acute phase, investigated before and during the pharmacological treatment (5-aminosalycilic acid and steroids), CRP values fell into the normal range after the second week of therapy, whereas TSA values reached the higher limit of the normal range after the third week, except for two CD patients with a larger location (ileocolonic) of the disease. The results are briefly discussed.

HLA-A, B, C, DR and DQ expression and hepatocellular carcinoma: study of 205 Italian subjects

We have evaluated the frequency of HLA class I and II antigens in 205 Italian patients with hepatocellular carcinoma (HCC) and 749 blood donors (controls). Moreover, we have looked for correlations between HLA antigen frequencies and HBV and/or HCV infections in HCC patients. We found great differences in HLA antigen frequencies considering only two groups: HCC patients and controls. The polymorphism is smaller when we consider the different groups of HCC patients in regard to the previous viral infections (HBV and/or HCV). The most interesting finding is the higher frequency of Cw7, B8 and DR3 in almost all groups of HCC patients. It is well known, that the HLA A1, Cw7, B8, DR3 antigen haplotype is associated with a rapid decline of CD4 cells, and HLA B8, DR3 positive subjects may display some changes in immune parameters and are prone to develop several immunological diseases. Thus HCC might be the result of a lower sensitivity (genetically given) to mitogenic stimuli of HBV and HCV.

Studies on the dissociation of cryptomonad biliproteins

The spectroscopic properties of two biliproteins, phycocyanin 645 and phycoerythrin 566, have been studied by treating the proteins with two different agents, NaSCN at pH 6.0, or pH 4.0 without NaSCN. For phycoerythrin 566, treatment with NaSCN revealed that the visible CD spectrum of its chromophores was separated into a pair of different spectra, and each of these spectra was observed as a negative and one or more positive bands. For phycocyanin 645, two negative CD bands have been observed previously, together with two or more positive bands, in the dimer (alpha 2 beta 2) state, and NaSCN treatment caused elimination of one of these negative bands. The dimer was stable at pH 6.0, but at pH 4.0 the spectra of phycocyanin 645 had one less negative band than those at pH 6.0. Chromatography demonstrated that phycocyanin 645 was a monomer (alpha beta) at pH 4.0. Monomers of cryptomonad biliproteins have never been observed before. Excitation at 514 nm, in picosecond time-resolved fluorescence studies, produced lifetimes of 11.0 and 45.2 ps for dimers and monomers, respectively. Excitation at 566 nm yielded times of 1.38 and 1.24 ps, for dimers and monomers, respectively. CD in the far UV showed that monomers and dimers had very similar secondary structures. These results have been used to test an hypothesis that proposed two types of exciton splitting among the chromophores of phycocyanin 645, and perhaps phycoerythrin 566 could also have this chromophore organization.

Cytoplasmic and periplasmic production of human placental glutathione transferase in Escherichia coli

An expression vector yielding large amounts of GST P1-1 in the cytoplasm of Escherichia coli was constructed. The recombinant enzyme, obtained after purification, was characterized in its physicochemical and kinetic properties and appeared to be indistinguishable from that purified from human placenta. However, N-terminal amino acid sequencing revealed that about 50% of the recombinant GST still contained methionine as the N-terminal amino acid. Such an incomplete processing was not simply due to overproduction of GST. In fact, under growth conditions that lead to a sharp decrease in the production of the protein the N-terminal methionine was not removed. GST was unable to translocate across the bacterial membrane when it was fused to the leader peptide of the pelB gene from Erwinia carotovora and accumulated in the cytoplasm in a soluble and active conformation. However, when this fusion protein was produced in a bacterial strain overexpressing the bacterial chaperonins GroEL and GroES, a fraction of GST was exported into the periplasmic space with the correct N-terminal sequence. The yield of correctly processed GST accounted for 12% of total GST present in the E. coli cells. Our results suggest that chaperonins are able to interact with nascent GST, thus maintaining the protein in an export-competent form and that E. coli strains with enhanced secretory characteristics may be obtained by genetic engineering technology.

Surgical reinstatement of aesthetics in the maxillary anterior region: a case report

The maxillary anterior region is frequently treated for aesthetic enhancement. This article presents the case of a patient who had undergone surgery for treatment of a tumor of the hypophysis involving intraoral access to the sella turcica. The treatment had caused the formation of severe gingival recession on the buccal surface of the maxillary anterior teeth. A variety of surgical techniques were considered for covering the exposed root surfaces. The surgical site was analyzed, and the response of the periodontal tissue to the treatment was anticipated. The bilaminar method, utilizing a subpedicle connective tissue graft (SCTG), was selected. The learning objective of this case presentation is to demonstrate that when the appropriate treatment procedure is selected, restoration of function and aesthetics can be achieved even in the most advanced cases.

Expansile subchondral degenerative bone cyst secondary to osteoarthritis

A 53-year-old man known to have osteoarthritis of the left knee was examined because of a soft-tissue swelling overlying the pes anserinus tendon. Plain radiography and computed tomography revealed an expansile subchondral cyst of the proximal tibia. The cyst was multiloculated, had a sclerotic margin and an extraosseous soft-tissue component, and interrupted the cortex. Proof of a degenerative cyst was obtained by open biopsy. Such presentation in the knee is rare. Awareness of the possible aggressive behaviour of such degenerative cysts should help avoid confusion with neoplasm.