Screening for the Gly40Ser mutation in the glucagon receptor gene among patients with type 2 diabetes or essential hypertension in Taiwan

As a major counterregulatory hormone of insulin, glucagon plays an important role in regulating glucose homeostasis through its binding to the glucagon receptor. Recently a missense mutation in the glucagon-receptor gene (Gly40Ser) was found to be associated with type 2 diabetes in France and Sardinia, with a frequency as high as 4.6% and 8.3%, respectively. This mutation was also found to be associated with essential hypertension in the white population with a frequency of 5.4%. To investigate the role of this mutation in the pathogenesis of type 2 diabetes and essential hypertension in Taiwanese population, we screened 121 normal controls, 213 unrelated subjects with type 2 diabetes, and 107 unrelated subjects with essential hypertension by use of polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP). None of the Taiwanese subjects recruited in the study had this receptor mutation. Our results demonstrate a strong genetic heterogeneity among the ethnic group and suggest that the Gly40Ser mutation of the glucagon receptor gene plays little role, if any, in the pathogenesis of type 2 diabetes and essential hypertension in the Taiwanese population.

Quantitative analysis of derivatized proteins prepared with pyridyl disulfide-containing cross-linkers by high-performance liquid chromatography

Determination of the introduced moieties into derivatized proteins is an essential step in the preparation and quality control of chemically defined immunoconjugates. For the derivatized proteins using pyridyl disulfide-containing cross-linkers such as N-succinimidyl 3-(2-pyridyldithio)propionate (SPDP) and 4-succinimidyloxycarbonyl-alpha-methyl-alpha-(2-pyridyldithio)tolu ene (SMPT), the derivatization degree (ratio of pyridyl disulfide moieties to protein) has been traditionally determined by measuring the absorbance of both the derivatized protein and 2-thiopyridone (2-TP) released from the dithiothreitol (DTT) treatment (spectrophotometric method). This method, however, causes several problems including false high and low determinations of the protein and 2-TP, respectively, low selectivity, poor reproducibility, and relatively large amounts of sample consumption. A quantitative determination method of the derivatization ratios using bovine serum albumin derivatized with SPDP and SMPT as the model system has been developed. The concentration of protein and 2-TP released from the DTT treatment of derivatized proteins was determined directly without consideration of different reagents used and their concentrations. The present HPLC method was proved to be better in terms of accuracy, selectivity, and reproducibility with micro sample consumption. Moreover, this HPLC method can be directly applied to all derivatized proteins prepared with pyridyl disulfide-containing cross-linkers.

p53-mediated repression of alpha-fetoprotein gene expression by specific DNA binding

Aberrant expression of the alpha-fetoprotein (AFP) gene is characteristic of a majority of hepatocellular carcinoma cases and serves as a diagnostic tumor-specific marker. By dissecting regulatory mechanisms through electromobility gel shift, transient-transfection, Western blot, and in vitro transcription analyses, we find that AFP gene expression is controlled in part by mutually exclusive binding of two trans-acting factors, p53 and hepatic nuclear factor 3 (HNF-3). HNF-3 protein activates while p53 represses AFP transcription through sequence-specific binding within the previously identified AFP developmental repressor domain. A single mutation within the DNA binding domain of p53 protein or a mutation of the p53 DNA binding element within the AFP developmental repressor eliminates p53-repressive effects in both transient-transfection and cell-free expression systems. Coexpression of p300 histone acetyltransferase, which has been shown to acetylate p53 and increase specific DNA binding, amplifies the p53-mediated repression. Western blot analysis of proteins present in developmentally staged, liver nuclear extracts reveal a one-to-one correlation between activation of p53 protein and repression of AFP during hepatic development. Induction of p53 in response to actinomycin D or hypoxic stress decreases AFP expression. Studies in fibroblast cells lacking HNF-3 further support a model for p53-mediated repression that is both passive through displacement of a tissue-specific activating factor and active in the presence of tissue-specific corepressors. This mechanism for p53-mediated repression of AFP gene expression may be active during hepatic differentiation and lost in the process of tumorigenesis.

Laryngeal pathology in the acquired immunodeficiency syndrome: diagnostic and therapeutic dilemmas

The acquired immunodeficiency syndrome has produced a growing population of patients who, because of their associated immune system compromise, are prone to opportunistic infections and neoplastic diseases. The larynx, with its relatively inaccessible yet critical anatomic location, is a site in which these processes can produce clinical dilemmas, with respect to diagnosis as well as to therapy. By presenting 4 cases involving unusual laryngeal problems in patients infected with the human immunodeficiency virus (HIV), we emphasize these inherent diagnostic and therapeutic problems. Otolaryngologists must be familiar with the many diagnostic possibilities and therapeutic alternatives when HIV-infected patients present with laryngeal complaints.

Limited joint mobility in diabetes

Cheiroarthropathy is a syndrome usually associated with diabetes mellitus that involves mainly the small joints of the hand. It is generally painless and seldom treated until hand deformity is severe enough to interfere with daily life. Because cheiroarthropathy is correlated with microvascular complications of diabetes, patients with hand symptoms should be carefully investigated for neuropathy, retinopathy, and nephropathy. Improved control of diabetes is the cornerstone of management, but surgery and corticosteroid injection may alleviate severe symptoms in some patients.

A frequent activated smoothened mutation in sporadic basal cell carcinomas

Basal-cell carcinomas (BCCs) are the most common cancer in Caucasians. It has been reported that the patched gene is inactivated in 30-40% sporadic BCCs and 20% sporadic medulloblastomas via loss of heterozygosity and nonsense mutations. Recently, two activating smoothened mutations have been found in the sporadic basal cell carcinomas. One, at base pair 1604 (G-to-T transversion) of exon 9, changes codon 535 from tryptophan to leucine, and the other, at base pair 1685 (G-to-A transition) of exon 10, changes codon 562 from arginine to glutamine (Xie et al., 1998). In our study, 1604G-->T was found in 20 out of 97 (20.6%) sporadic BCCs. The high prevalence indicates that 1604G is the mutation hot spot in our tumor samples. This mutation was detected in all three histological subtypes of BCCs, suggesting that smoothened mutation is an early event during the development of the tumor. Our finding of a high smoothened mutation rate, together with high frequent patched gene mutations reported recently, indicates that activation of the hedgehog signal transduction pathway is the most common and early event in the development of sporadic BCCs. Additionally, to determine whether smoothened, like patched, is also involved in the carcinogenesis of medulloblastomas, we screened medulloblastoma samples for these two mutations by restriction analysis. We have found the 1604G-->T mutation in 1 out of 21 medulloblastomas. This result confirmed smoothened gene involvement in the carcinogenesis of medulloblastoma.

Recanalization of completely thrombosed giant aneurysm: case report

BACKGROUND

Spontaneous recanalization in a completely thrombosed giant aneurysm is a very rare condition.

CASE DESCRIPTION

An 18-year-old woman presented with a serpentine variety giant aneurysm of the posterior cerebral artery, in which spontaneous recanalization of a completely thrombosed lumen was demonstrated on magnetic resonance imaging and angiography. The patient was treated by trapping of the parent artery and aneurysmectomy.

CONCLUSION

This case will provide insight into the potential for spontaneous recanalization in completely thrombosed giant aneurysms.

Gastro-intestinal cytomegalovirus infection and extensive colonic ulceration in a renal transplant recipient

Cytomegalic inclusion disease is a common complication in recipients of organ transplants. In renal transplant recipients, the disease involves the lungs more often than it does the gastrointestinal tract. We report on a recipient of a cadaveric kidney who had cytomegalic inclusion disease that involved both the upper and lower gastro-intestinal tract, and massive gastro-intestinal bleeding that was caused by a large colonic ulcer. Despite treatment with ganciclovir and cytomegalovirus-specific immunoglobulin, the patient died from subsequent complications.

Guidelines for using insulin lispro

OBJECTIVE

To review the best evidence-based literature on the insulin analogue, lispro insulin, and to provide guidelines for its use.

QUALITY OF EVIDENCE

Using the MeSH terms, lispro and insulin analogues, we searched PubMed, Current Contents, MEDLINE, and EMBASE from January 1986 to July 1998 and selected 42 articles out of 97 for high quality and relevance to family medicine. Twenty-eight were randomized controlled trials, but only two studies were blinded because lispro and regular insulin have different optimal times of administration.

MAIN MESSAGE

The new insulin analogue, lispro, produces a much more rapid, higher, and shorter-lasting peak level of insulin than regular human insulin, thus mimicking physiologic secretion of insulin more closely. This allows insulin administration just before or just after meals and means patients can manage with fewer snacks. Lispro controls postprandial blood glucose levels better and does not cause hypoglycemia. Although most older studies showed no change in glycosylated hemoglobin (HbA1c) levels, a few recent studies involving refinements, such as continuous subcutaneous insulin infusion or basal insulin to reduce preprandial glucose levels, have found small but significant improvements. Insulin lispro has also been used successfully in cases of insulin resistance and insulin allergy.

CONCLUSIONS

Lispro is a useful addition for motivated diabetic patients who like to achieve better control of HbA1c without increased hypoglycemia and to match mealtime insulin injections with diet, exercise, and various lifestyles.

Calculating the Effects of Longitudinal Resistance in Multi-Series-Connected Quantum Hall Effect Devices

Many ac quantized Hall resistance experiments have measured significant values of ac longitudinal resistances under temperature and magnetic field conditions in which the dc longitudinal resistance values were negligible. We investigate the effect of non-vanishing ac longitudinal resistances on measurements of the quantized Hall resistances by analyzing equivalent circuits of quantized Hall effect resistors. These circuits are based on ones reported previously for dc quantized Hall resistors, but use additional resistors to represent longitudinal resistances. For simplification, no capacitances or inductances are included in the circuits. The analysis is performed for many combinations of multi-series connections to quantum Hall effect devices. The exact algebraic solutions for the quantized Hall resistances under these conditions of finite ac longitudinal resistances provide corrections to the measured quantized Hall resistances, but these corrections do not account for the frequency dependences of the ac quantized Hall resistances reported in the literature.

Do clinical breast examination skills improve during medical school?

PURPOSE

To assess the effects of stage of training, gender, and specialty interest on medical students' breast cancer knowledge, attitudes, and clinical breast examination (CBE) skills as a case study of the progression of physical examination skills during medical education.

METHOD

In 1996, questionnaires assessing breast cancer knowledge and attitudes were administered to 493 premedical and first-, second-, and third-year medical students at Northwestern University Medical School. Silicone breast models were used to evaluate the CBE proficiency of a subset of 151 students.

RESULTS

Breast cancer knowledge was positively correlated with stage of training (r = .62), with significant differences between all levels (p < .001). In contrast, first-year medical students attained the highest mean lump-detection sensitivity (61.5%), followed by second-year (53.9%) and third-year (43.5%) students (p < .001, first- vs third-year students; p < .10, second- vs third-year students). There was no significant difference in specificity among the four stages.

CONCLUSIONS

The results suggest that breast cancer knowledge and attitudes are not related to CBE proficiency, which is a practiced tactile skill. The decline in lump-detection sensitivity with increased stage of training may demonstrate the need for increased attention to palpation skills during the clinical years. These findings are consistent with those of earlier reports that suggest the need for the reinforcement of physical examination skills during clinical education.

Doxycycline sclerosis of benign lymphoepithelial cysts in patients infected with HIV

Benign lymphoepithelial cysts (BLCs) are a widely recognized cause of parotid gland swelling in HIV-infected patients. Although they are neither invasive nor associated with malignant degeneration, BLCs can become large and disfiguring. Multiple modalities have been used to control these cysts, but no ideal treatment has been identified. The current study examines the efficacy of doxycycline as a BLC sclerosant in eight patients, and nine BLCs (bilateral BLC in one patient). Follow-up ranged from 12 to 17 months in all cases. Doxycycline sclerosis controlled further cyst growth in 100% of cases with no serious complications. The BLCs became negligible or unnoticeable in two patients, and in six patients (seven BLCs) the cyst became fibrosed and showed no evidence of further growth over the follow-up period. Although further studies are needed to determine the long-term efficacy of this treatment modality, doxycycline sclerosis appears to offer a simple, safe, cost-effective, office-based therapeutic option for the treatment of BLCs in patients infected with HIV.

Purification of Sepharose-unbinding ricin from castor beans (Ricinus communis) by hydroxyapatite chromatography

Sepharose-unbinding ricin was one-step separated and purified from a crude extract of castor beans (Ricinus communis) by affinity chromatography on hydroxyapatite. This purification method does not require the time-consuming and complicated steps, such as gel filtration and ion-exchange chromatography, that have been essential in the separation of Sepharose-unbinding toxins. Using this method, approximately 180 mg of ricin was obtained from 100 g of castor beans using a bed volume of 80 ml on a hydroxyapatite column. Weak affinity of the ricin on Sepharose was confirmed and compared with Sepharose-binding ricin (ricin D), using radioiodinated ricins. The molecular mass of the ricin was estimated to be 62 kDa by 10% SDS-PAGE under nonreducing conditions. Under reducing conditions, the purified ricin appeared to be two subunits, corresponding to the molecular masses of 30 and 32 kDa. The pI value was determined to be approximately 8.9 for the ricin. Uptake of the ricin by HeLa cells was measured as almost half of ricin D uptake. Similar results were observed on CEM cells as well. In vitro cytotoxicity of ricins on different cell lines was measured by the MTT method. When compared with ricin D, the purified ricin showed approximately 10-fold less cytotoxicity to HUT78 or K562 cells and 30-fold less toxicity to CEM cells. This lower cytotoxicity of the ricin may be due to its lower cell-binding properties as evidenced by its low affinity for the cell surfaces. From these results, the purified ricin was considered to be ricin E.

Contemporary presentation and management of a spectrum of mastoid abscesses

BACKGROUND

The incidence of complications resulting from suppurative otitis media has significantly decreased since the introduction of antibiotics. At the start of the 20th century 50% of all cases of otitis media developed a coalescent mastoiditis. By 1959, the incidence had fallen to 0.4%. Recent studies suggest a current incidence of only 0.24%. Additionally, during the time of Friedrich Bezold (1824-1908), 20% of patients with mastoiditis developed subperiosteal abscess. Interestingly, this has incidence increased; today nearly 50% of patients diagnosed with coalescent mastoiditis have subperiosteal abscess.

OBJECTIVE

To review the contemporary presentation, diagnosis, and management of a spectrum of mastoid abscesses.

DESIGN

Retrospective case series.

SETTING

Hospitals associated with the Department of Otolaryngology/Head and Neck Surgery at the University of California, San Francisco.

PATIENTS

Three patients with mastoid abscesses are reported. One patient displayed "classic" Bezold's abscess, with pus escaping the mastoid near the incisura digastrica and tracking along the digastric and sternocleidomastoid muscles into the neck. The second and third patients exhibited temporoparietal swelling secondary to mastoid abscess eroding the root of the zygomatic process, a complication noted by Bezold in 1908 as occurring "in only very rare cases."

RESULTS AND CONCLUSIONS

Since only one third of patients show pathologic tympanic membrane changes, and since complaints of otalgia, fever, and tenderness are inconstant, subperiosteal mastoid abscess is frequently a delayed diagnosis. The clinical presentation, pathogenesis, and routes of abscess spread are presented with photographic and radiographic illustration. Medical and surgical management is reviewed, and methods for accurate diagnosis are emphasized.

Formation of high axial ratio microstructures from peptides modified with glutamic acid dialkyl amides

A growing number of amphiphiles are known to form high axial ratio microstructures (HARMs) such as the hollow cylindrical microstructures called lipid tubules. As a prelude to exploring the potential of HARMs formed from lipopeptides in controlled release drug delivery, several microstructure formation conditions were investigated. We report the preparation of several glutamic acid dialkyl amides with varying alkyl chain lengths bearing a verity of peptides (1-4 amino acids) [peptide-Glu-(NHCnH2n+1)2, n=12, 14, 16]. These surfactants have been rapidly and efficiently converted into HARMs in aqueous buffer at physiological pH and ionic strength, or in buffer containing MeOH or EtOH. Helical ribbons and tubular HARMs were produced that were stable for as long as 6 months below the phase transition temperatures of the compounds. To estimate the stability of HARMs in vivo, HARMs formed from (Pro)3-Glu(NHC16H33)2 were incubated with DOPC liposomes or fetal calf serum at 40 degreesC. HARM size and shape did not change significantly, suggesting that such lipopeptide particles can retain their morphology long enough in vivo to be useful as drug delivery vehicles.

Intraperitoneal pulse calcitriol in the treatment of secondary hyperparathyroidism in patients on continuous ambulatory peritoneal dialysis

OBJECTIVE

To determine whether it is practicable to use intraperitoneal calcitriol to treat continuous ambulatory peritoneal dialysis (CAPD) patients with secondary hyperparathyroidism and whether this form of therapy is effective and safe.

DESIGN

A prospective, nonrandomized study.

SETTING

Division of Nephrology, Tertiary Hospital.

METHOD

Eight patients from our CAPD population were recruited (5 F, 3 M), aged 24 to 63 years (mean 38.9 +/- 7.6 yr). They had been on CAPD for 8 to 84 months (mean 47.6 +/- 24.6 months). All the patients had bone biopsy-proven secondary hyperparathyroidism with 2 patients showing mixed lesions. The CAPD system was changed to the twin-bag system (Ultrabag, Baxter Healthcare, McGaw Park, IL, U.S.A.) in all 8 patients, who were taught to inject the calcitriol directly through the short transfer set and the Tenckhoff catheter into the peritoneal cavity, twice per week before bedtime. Calcium carbonate or calcium acetate was used as the main phosphate binder. Intact parathyroid hormone level (iPTH), serum ionized calcium (iCa), serum phosphate, and serum total alkaline phosphatase (alk. phos.) levels were measured at baseline and then every 4 weeks. The mean duration of follow-up was 10.5 months +/- 1.9 months.

RESULTS

There was a significant drop of iPTH level from the pretreatment level of 100.6 +/- 35.8 pmol/L to a level of 63.8 +/- 48.7 pmol/L at 24 weeks (p = 0.036). The lowest level of iPTH attained was 43.4 +/- 27.0 pmol/L at 48 weeks. Serum total alk. phos. also dropped from 232.4 +/- 83.3 IU/L pretreatment to 147.9 +/- 52.0 IU/L at 24 weeks (p = 0.017). The decrease in alk. phos. level paralleled the decrease in iPTH level. The mean serum iCa level did not show any significant rise throughout the study period. The maximum dose of calcitriol used was 6.6 +/- 1.5 microg/week and the average dose of calcitriol was 5.4 +/- 1.2 microg/week. One patient did not respond satisfactorily and she subsequently had a parathyroidectomy. Two episodes of peritonitis occurred during the study period, giving a peritonitis rate of one episode per 42 patient-months. There was no significant change in the urea clearance tests or the peritoneal equilibration tests before and after the study.

CONCLUSION

Intraperitoneal calcitriol is practicable, effective, and safe in the treatment of secondary hyperparathyroidism in CAPD patients.

Phylogenetic analysis of triple gene block viruses based on the TGB 1 homolog gene indicates a convergent evolution

The complete nucleotide sequence of the triple gene block one (TGB 1) of cymbidium mosaic potexvirus (CymMV) was compared to those from other potex-, carla-, furo- and hordeiviruses. Seven conserved motifs in the TGB 1, including the ATP-GTP binding domain (P-Loop) consensus GXXGKTSTS, were found in all four virus genera. We propose that all TGBV can be classified into phylogenetic clusters based on their TGB 1 homolog genes. These clusters can be further delineated to form subgroups. The first cluster comprises the potexviruses which are further subdivided into three subgroups; BaMV, FMV, PlaMV and PapMV (subgroup Ia); CymMV, PAMV, NMV, SMYEaV and WC1MV (subgroup Ib) and PVX (subgroup Ic). The second cluster comprises carlaviruses with a dual subgrouping; CVB, LSV, PVM, PMV and ASPV (subgroup IIa) and LVX (subgroup IIb). The third cluster carries the most diverse of TGBV comprising furoviruses PCV, PMTV and BSBV (subgroup IIIa) and hordeiviruses PSLV, BSMV and LRSV (subgroup IIIb). The phylogenetic relationships of triple gene block viruses (TGBV) based on the TGB 1 homolog gene indicates a convergent evolution.

Stability of Octastatin, a somatostatin analog cyclic octapeptide, in aqueous solution

In this study, the degradation of Octastatin, a cyclic octapeptide analog of somatostatin, was examined as a function of pH, temperature, buffer, and ionic strength by reversed-phase gradient high-performance liquid chromatography. Degradation of Octastatin followed a first-order kinetics. Various buffer species such as acetate, ammonium acetate, citrate, glutamate, phosphate, and borate showed differing effects on the degradation of the octapeptide. Good stability was found in glutamate and acetate buffer of pH 4.0. Degradation of Octastatin was greater in citrate- or phosphate-containing buffers than in glutamate or acetate buffers. With phosphate buffer, higher buffer concentration caused greater degradation, while in acetate buffer, the effect of buffer concentration and ionic strength was negligible. In addition, the degradation of Octastatin was markedly inhibited by increasing the concentration of glutamate buffer. This study allows the prediction of good stability in acetate buffer (0.01 M, pH 4.0) with a t90% of 84.1 days at 20 degrees C.