Lower serum magnesium levels are associated with more rapid decline of renal function in patients with diabetes mellitus type 2

AIMS

Hypomagnesemia has been implicated in adversely affecting diabetic complications. This is a retrospective study designed to determine whether there is any association between serum magnesium concentration [Mg2+] and the rate of renal function deterioration, as determined by the slope of serum creatinine reciprocals versus time (1/SCr-vs-t), in patients with diabetes mellitus type 2 (DM2).

MATERIALS AND METHODS

DM2 patients without known kidney disease seen at Olive View-UCLA Medical Center for any reason during January-March 2001 were included. For each patient, all available data from our electronic database for [Mg2+], hemoglobin A(1C) (HbA(1C), serum creatinine (SCr), lipid profiles, routine urinary analysis, as well as history of hypertension and pharmacy profiles were retrieved. The average of all parameters obtained and linear regression analyses for the slope of 1/SCr-vs-t plot were performed for each patient. Patients were stratified by gender and divided into four groups based on increasing [Mg2+]. Correlations between each parameter including the slope of 1/SCr-vs-t and the four magnesium groups were analyzed.

RESULTS

252 males and 298 females with a mean follow-up of 62.6 +/- 22.5 months were included. Patients belonging to lower [Mg2+] groups for both genders had significantly worse slopes of 1/SCr-vs-t plot independent of the presence of hypertension and use of ACEI/ARB, diuretics, HMG-CoA enzyme inhibitors or aspirin. In a multivariate regression analysis controlling for age, HbA(1C) and various components of the lipid profile, [Mg2+] remained an independent predictor for the slope of 1/SCr-vs-t. A trend for worse proteinuria based on routine urinary analysis was observed among patients belonging to the lowest [Mg2+] group.

CONCLUSIONS

Lower [Mg2+] is associated with a faster renal function deterioration rate in DM2 patients.

[Shielding effect of protective seats during CT examination]

Because the exposure to radiation from CT scanning is higher than that from other X-ray diagnostic devices, it is necessary to lower this exposure. In this study, we placed a protective seat on the abdomen and dorsal side of a human body phantom. Three different kinds of CT units, with a single detector, four detectors, and 16 detectors, were used to compare the absorbed dose on the skin surface and uterus. Head and chest CT scans were taken with the standard protocol. The difference in exposure to the uterus with and without the protective shield was found to be small. Exposure to the skin surface was about 0.2 mGy without the protective seat. We found that the exposure dose to chest could be reduced as much as 50% by using the protective seat. Effective radiation differs depending on the institution, and these differences can be more than the amount that can be reduced by using the protective seat. Thus, we conclude that it is important for each institution to determine the best protocol optimization for each individual.

Automatic measurement of polyethylene modification in metal-backed artificial hip joints using three-dimensional CT

A new method has been developed for automatic measurement of polyethylene linear modification using three-dimensional CT in total hip arthroplasty (THA) and bipolar hemiarthroplasty (BHP). We obtained a three-dimensional digital image of the metal components by widening the maximum window width, adjusting the proper cutoff threshold level, and removing the metal artifact. The centric coordinates of both the metal-backed cup and the femoral head were calculated from this image. Modification was defined as a change in distance between those two points from their original interval. Phantom studies of the accuracy and reproducibility of the method indicated that the average error ranged from 0.02 to 0.12 mm and the standard deviation ranged from 0.01 to 0.05 mm. Clinical in vivo measurement was performed without error of computer software on 19 hips in which modification of highly cross-linked polyethylene components was significantly large.

Role of Women in Medicine: A Look at the History, the Present Condition and the Future Status of Women in the Surgical Field, Especially Neurosurgery

We have analyzed the historical background of women's progress in medicine in Japan and the role of female neurosurgeons as models for the next generation. Female neurosurgeons were asked to complete a questionnaire regarding their professional life in detail and the problems they are facing while managing their personal life after getting married and having a child. Some feel that there remain some constraints at work for being a female, due to their male colleagues who are not so understanding in nature. The younger generation is not so keen on joining the neurosurgical branch as their life career due to hard work and complete dedication demanded by neurosurgery. It is not easy for all to manage a neurosurgical career along together with a married life and children. Hence it is now time for those successful female neurosurgeons to become role models. Government can play an important role in these social reforms by coming up with programs to give social security to females and initiate programs for child care for married females pursuing such a demanding profession. Certain measures to encourage females to take up surgery are providing more time by arranging care for babies and families, flexibility in working hours, in addition to having a considerate husband and a considerate chief of department and senior staff. Departmental policies need to be completely impartial and should promote everyone based on their skills and knowledge. Women neurosurgeons need to get together and discuss all these issues so that the younger generation will not hesitate to take up this profession and become stalwarts of neurosurgery like their male counterparts.

Complications of pulmonary vein isolation by catheter ablation evaluated by ECG-gated multislice computed tomography

As pulmonary vein (PV) isolation by catheter ablation for paroxysmal atrial fibrillation may cause PV luminal stenosis, digital subtraction angiography or magnetic resonance imaging have been used to evaluate the lumen of the PV. Electrocardiogram-gated multislice computed tomography can evaluate the lumen of the PV from any plane desired after acquisition with excellent spatial resolution. It can also evaluate hyperplasia of soft tissue around the lumen of the PV, which cannot be evaluated by digital subtraction angiography, and may thus serve as an indicator of complications or even the effectiveness of this treatment.

Dose evaluation and effective dose estimation from CT fluoroscopy-guided lung biopsy

The development of computerized tomography (CT) has made CT fluoroscopy possible with real-time CT images. However examination are expected to have high medical and occupational exposures. Then, exposures to patients and operating and assisting physicians during the CT fluoroscopy-guided lung biopsy were estimated. And changes in the examination conditions to lower the dose were made. Patient exposure was measured using an anthropomorphic phantom by simulation of clinical examination conditions. The surface dose to the physician was measured during actual clinical examinations. The average effective dose for the patient was 34+/-22mSv. The highest surface dose amounted to 1.9 Gy, although this was in a very narrow field. Patient doses could be reduced by a factor of 2.5-3 by changing examination methods while still retaining diagnostic quality. The highest dose to the operating physician was 10mGy which was recorded on the back of the hand and the average effective dose was estimated as 5.99&mgr;Sv per 1-minute examination. Doses were reduced by about a factor of 50 by lowering the tube voltage from 120kV to 80 kV and using a supplementary tool. The doses for assisting physicians were not significant. The exposure for physicians and patients was much affected by lowering the tube voltage used for fluoroscopy. Using a supplementary tool was effective for reducing the dose for physicians.

Requirement of c-jun N-terminal kinase for apoptotic cell death induced by farnesyltransferase inhibitor, farnesylamine, in human pancreatic cancer cells

Farnesyltransferase inhibitors (FTIs) represent a novel class of anticancer drugs and are now in clinical trial. We have previously shown that farnesylamine, synthetic isoprenoid-linked with "amine" which acts as a potent FTI, induces apoptosis in human pancreatic cancer cells through the ras signaling cascade. Since the effect of FTI is usually "cytostatic" rather than "cytotoxic", we speculated another apoptotic machinery of farnesylamine in addition to the effect of FTI. Farnesylamine induced sustained activation of c-jun N-terminal kinase (JNK), which was not caused by other FTI, FTI-277. Blockage of JNK activity by dominant-negative mutant abrogated the DNA laddering and significantly reduced "cytotoxic" effect of farnesylamine. Strikingly similar effect on JNK activation and apoptosis was induced by structurally related long-chain fatty amine (LFA), oleylamine, but not by farnesol, an isoprenoid analogue of farnesylamine without "amine." Taken together, apoptosis induction through JNK activation by farnesylamine based on the LFA structure rather than an effect of FTI.

Clonality and field cancerization in intraductal papillary-mucinous tumors of the pancreas

BACKGROUND

Multiple lesions of intraductal papillary-mucinous tumor of the pancreas (IPMT) in the same pancreas often are encountered. To elucidate field (multicentric) cancerization and clonality of IPMT, clonal analyses of IPMT and its precursor lesion of ductal hyperplasia were performed. K-ras codon 12 mutations and X-chromosome inactivation of human androgen receptor gene (HUMARA) were investigated.

METHODS

Paraffin embedded tissue samples from the pancreata of 37 patients who underwent resection for IPMTs were microdissected manually or by laser capture microdissection. Multiple samples from each surgical specimen were microdissected representing each IPMT and discrete ductal hyperplasias. DNA was extracted, and K-ras codon 12 mutations were examined by two-step polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The mutations were analyzed by direct DNA sequence. The HUMARA locus was digested with or without HpaII and HhaI prior to amplification. The HUMARA assay was conducted by fluorescence-labeled PCR-RFLP and was analyzed with specialized software.

RESULTS

All 37 pancreata had at least two lesions of ductal hyperplasia, and 23 of 37 pancreata (62%) had K-ras codon 12 mutations in these precursor lesions. Of 23 pancreata with mutated K-ras hyperplasia, 15 (65%) had multiple, distinct mutations in different lesions of hyperplasia in the same pancreas, suggesting a field defect. Thirty-two of 37 IPMTs (86%) had K-ras codon 12 mutations. Among these, 16 IPMTs (50%) had multiple, distinct mutations at K-ras codon 12. The HUMARA assay showed that 12 of 15 IPMTs were informative, and 9 were considered polyclonal and/or oligoclonal origin in origin. With the combined results of multiple K-ras mutation detection and the HUMARA assay, 12 of 15 IPMTs from female patients (80%) were considered polyclonal and/or oligoclonal in origin.

CONCLUSIONS

The current results suggest that multiple, distinct K-ras mutations of different ductal hyperplasias in a given pancreas are due to a field (multicentric) cancerization effect in IPMTs. Thus, most of IPMTs are polyclonal and/or oligoclonal in origin, i.e., IPMTs may originate from multiple (molecularly distinct) precursor lesions.

Riboflavin transport by isolated perfused rabbit renal proximal tubules

Rabbit renal proximal tubular transport of riboflavin (RF) was examined by using the in vitro isolated tubule perfusion technique. We found that proximal tubules actively reabsorbed (J(lb)) and secreted (J(bl)) RF. At 0.1 microM RF concentration, J(bl) was significantly higher than J(lb), resulting in a net secretion. This net secretion of RF was decreased at 0.01 microM RF concentration and increased at 1 microM RF concentration. Both J(lb) and J(bl) were inhibited by lowering temperature or by adding iodoacetate, a metabolic inhibitor, and lumichrome, an RF analog, suggesting the involvement of carrier-mediated transport mechanisms. J(bl) was inhibited by probenecid, an anion transport inhibitor, and by para-aminohippuric acid, an organic anion, suggesting the relevance of RF secretion to renal organic anion transport. J(bl) was also inhibited by alkaline pH (8.0) and by the calmodulin inhibitor trifluoperazine, indicating the influence of pH and Ca(2+)/calmodulin-dependent pathway on RF secretion. Finally, we found that addition of chlorpromazine, a phenothiazine derivative, inhibited both J(lb) and J(bl), raising the concern about the nutritional status in patients receiving such a type of medication.

Epithelial cell proliferation and gene mutation in the mucosa of gallbladder with pancreaticobiliary malunion and cancer

The significant association between pancreaticobiliary malunion (PBM), especially undilated-type PBM, and a high risk of gallbladder cancer is known. Reflux and stasis of pancreatic juice induce various epithelial changes in the gallbladder. Recently, epithelial hyperplasia of the gallbladder was shown to be significantly and frequently associated with undilated-type PBM, and it is suggested that the majority of epithelial hyperplasia may exist at birth or be acquired in early childhood, and thereafter present throughout the lives of PBM patients. Cell kinetic studies demonstrated a significant stepwise increase in cellular proliferative activity from normal gallbladder mucosa, through epithelial hyperplasia to cancer. Epithelial hyperplasia with increased proliferative activity may predispose the mucosa to mutational events, thereby increasing cancer risk in PBM patients. K-ras mutations were frequently detected in gallbladder cancer in PBM patients and in epithelial hyperplasia as well. Epithelial hyperplasia is demonstrated to be an important premalignant lesion of gallbladder cancer. A multistep process of carcinogenesis as a consequence of multiple genetic alterations of oncogenes and tumor suppressor genes has been demonstrated in various organs; however, there is limited information on the molecular mechanism in gallbladder carcinogenesis with PBM. Recent findings support the idea that epithelial hyperplasia plays an important role in gallbladder carcinogenesis with PBM and also support the concept that neoplastic development in gallbladder with PBM also evolves through a multistep process associated with hyperproliferation and genetic alterations.

Riboflavin uptake by human-derived colonic epithelial NCM460 cells

Normal microflora of the large intestine synthesize a number of water-soluble vitamins including riboflavin (RF). Recent studies have shown that colonic epithelial cells possess an efficient carrier-mediated mechanism for absorbing some of these micronutrients. The aim of the present study was to determine whether colonic cells also possess a carrier-mediated mechanism for RF uptake and, if so, to characterize this mechanism and study its cellular regulation. Confluent monolayers of the human-derived nontransformed colonic epithelial cells NCM460 and [(3)H]RF were used in the study. Uptake of RF was found to be 1) appreciable and temperature and energy dependent; 2) Na(+) independent; 3) saturable as a function of concentration with an apparent K(m) of 0.14 microM and V(max) of 3.29 pmol x mg protein(-1) x 3 min(-1); 4) inhibited by the structural analogs lumiflavin and lumichrome (K(i) of 1.8 and 14.1 microM, respectively) but not by the unrelated biotin; 5) inhibited in a competitive manner by the membrane transport inhibitor amiloride (K(i) = 0.86 mM) but not by furosemide, DIDS, or probenecid; 6) adaptively regulated by extracellular RF levels with a significant and specific upregulation and downregulation in RF uptake in RF-deficient and oversupplemented conditions, respectively; and 7) modulated by an intracellular Ca(2+)/calmodulin-mediated pathway. These studies demonstrate for the first time the existence of a specialized carrier-mediated mechanism for RF uptake in an in vitro cellular model system of human colonocytes. This mechanism appears to be regulated by extracellular substrate level and by an intracellular Ca(2+)/calmodulin-mediated pathway. It is suggested that the identified transport system may be involved in the absorption of bacterially synthesized RF in the large intestine and that this source of RF may contribute toward RF homeostasis, especially that of colonocytes.

Effects of Duraflo II heparin-coated cardiopulmonary bypass circuits on the coagulation system, endothelial damage, and cytokine release in patients with cardiac operation employing aprotinin and steroids

The effects of Duraflo II heparin coated cardiopulmonary bypass circuits, low-dose aprotinin, and steroids on the coagulation system, endothelial damage, and cytokine release were evaluated by comparing those treated with low-dose aprotinin and steroids. Twenty-four adult patients undergoing coronary artery bypass grafting, aortic valve replacement, or valve repair surgery were randomly assigned to 2 groups: either heparin-coated (Duraflo group, n = 12) or noncoated equipment (noncoated group, n = 12) groups. In the Duraflo group, the cardiopulmonary reservoir was also coated with heparin. There were no significant differences in age at the time of operation, aortic cross-clamp time, cardiopulmonary bypass time, and rectal temperature during cardiopulmonary bypass. Standard systemic heparinization was performed. Methylpredonisolone and low-dose aprotinin were given in both groups of patients. Serum XIIa factor, TAT, and IL-6 were significantly higher in the control group than in the Duraflo group during cardiopulmonary bypass (p < 0.01). Serum IL-8 was significantly higher in the control group than in the Duraflo group at 24 h after cardiopulmonary bypass (p < 0.05). No significant difference was found in serum thrombomodulin and TNF-alpha; both were within normal during the study period. These results indicate that the use of Duraflo II heparin coated equipment and a heparin-coated cardiopulmonary reservoir suppressed excess coagulation and inflammatory reaction induced by cardiopulmonary bypass.

Epithelial hyperplasia of the gallbladder in children with anomalous pancreaticobiliary ductal union

BACKGROUND/AIMS

Few data are available on the fate and incidence of epithelial hyperplasia throughout the life of anomalous pancreaticobiliary ductal union (APBD) patients. The pathological study in pediatric APBD patients is less recognized.

METHODOLOGY

Ten resected gallbladders obtained from children with APBD and control patients without APBD were examined histologically, and immunohistochemically for the detection of Ki-67 (as a proliferative marker) and p53. K-ras mutations in codon 12 were also examined. Epithelial hyperplasia was classified into high-grade and low-grade hyperplasia.

RESULTS

Six (60%) of 10 patients with APBD had epithelial hyperplasia of the gallbladder, whereas no patients without APBD exhibited this lesion. Diffuse epithelial hyperplasia was observed in 1 (50%) of 2 undilated-type APBD and 5 (63%) of 8 dilated-type. Two (33%) of 6 patients with epithelial hyperplasia exhibited high-grade hyperplasia. Ki-67 labeling index (LI) was significantly higher in hyperplastic mucosa than in control gallbladder mucosa. K-ras mutations and p53 overexpression were not detected in hyperplastic and normal mucosa.

CONCLUSIONS

Epithelial hyperplasia of the gallbladder accompanied by increased proliferative activity exists at birth or is acquired in childhood with APBD patients and may be an important factor predisposing to the development of gallbladder carcinoma.

Chloride dependency of renal brush-border membrane phosphate transport

In our present study, we examined the effect of Cl(-) on rabbit renal brush-border membrane (BBM) phosphate (P(i)) uptake. It was found that the Na(+)-dependent BBM (32)P uptake was significantly inhibited by Cl(-) replacement in the uptake solution with other anions, or by Cl(-) transport inhibitors, including DIDS, SITS, diphenylamine-2-carboxylate (DPC), niflumic acid (NF), and 5-nitro-2-(3-phenylpropylamino)benzoate (NPPB). Intravesicular formate or Cl(-) increased BBM (36)Cl(-) uptake but did not affect BBM (32)P uptake. BBM (22)Na(+) uptake was lowered by Cl(-) replacement in the uptake solution but not by Cl(-) transport inhibitors. Changes in transmembrane electrical potential altered BBM (36)Cl(-) and (32)P uptake in directions consistent with a net inward movement of negative and positive charges, respectively. However, the Cl(-)-dependent BBM P(i) uptake was not affected by changes in transmembrane electrical potential. Finally, a similar Cl(-) dependency of P(i) uptake was also found with BBM derived from rat and mouse kidneys. In summary, our study showed that a component of Na(+)-dependent P(i) uptake was also Cl(-) dependent in rabbit, rat, and mouse renal BBM. The mechanism underlying this Cl(-) dependency remains to be identified.

Riboflavin transport by rabbit renal basolateral membrane vesicles

The present study examined riboflavin (RF) uptake by isolated rabbit renal basolateral membrane (BLM). RF uptake was linear during the initial 10 seconds and leveled off thereafter with longer incubation. Studies on RF uptake as a function of incubation medium osmolarity indicated that the BLM RF uptake was the results of transport (approximately 45%) into the intravesicular space as well as binding (approximately 55%) to membrane surfaces. The RF binding to BLM was Na+-dependent so that replacement of Na+ by other cations eliminated the binding component of RF uptake. The process of BLM RF uptake was saturable as a function of substrate concentration and was significantly inhibited by cis-addition of its structural analogs, lumiflavin and lumichrome, indicating the involvement of a carrier-mediated process. The BLM RF uptake was affected by changes in extravesicular pH so that, as compared to pH 7.5, RF uptake was lower at pH 6.5 and higher at pH 8.5. The effect of extravesicular pH persisted when the transmembrane H+ gradient was dissipated by FCCP, indicating the direct effect of pH on BLM RF uptake. The BLM RF uptake was not affected by alterations of the transmembrane electrical potential, induced by either the presence of anions with different membrane permeability (Cl-=NO-3>SO-4>gluconate-) or using nigericin (10 microg/mg protein) with an outwardly or inwardly directed transmembrane K+ gradient. The BLM RF uptake was, however, inhibited by probenecid and p-aminohippurate, and was enhanced by trans-RF. In summary, these results demonstrate the existence of a Na+-dependent BLM binding of RF and a membrane-associated carrier system for RF uptake by renal BLM.

Is angiotensin II a key regulator of proximal tubular function? Some answers and new questions

Recent studies have revealed the existence of intrarenal renin-angiotensin system and broadened our understanding on the role of angiotensin II in the regulation of proximal tubular functions. The aims of the present review are to summarize these recent findings and to highlight new questions that have arisen therefrom.

Peripheral blood mononuclear cells express mutated NCCT mRNA in Gitelman's syndrome: evidence for abnormal thiazide-sensitive NaCl cotransport

Genetic analysis has demonstrated complete linkage between the human thiazide-sensitive sodium chloride cotransporter gene (NCCT or TSC) and Gitelman's syndrome (GS). Several genomic NCCT mutations have been reported. This study was performed to determine whether peripheral blood mononuclear cells (PBMC) express NCCT mRNA and whether defective PBMC NaCl cotransport could be demonstrated in GS. PBMC were isolated from two brothers with GS, their parents, and healthy control subjects. Northern analysis revealed that NCCT mRNA is expressed in PBMC. The sequence of full-length NCCT cDNA amplified from normal PBMC was identical to human renal NCCT cDNA. Two different mutations were detected in the patients' NCCT cDNA (compound heterozygote). In cDNA derived from the patient's maternal allele, exon 24 was deleted, resulting in a premature stop codon (after amino acid 920). cDNA derived from the patient's paternal allele had an additional 119-bp insertion between exons 3 and 4, generating a premature stop codon (after amino acid 187). The patient's genomic DNA had a previously described 5' splice site mutation in intron 24, GGT --> GTT (maternal allele), and a new 3' splice site mutation in intron 3, CAG --> CAA (paternal allele), which resulted in the activation of a nearby cryptic splice site in intron 3. The latter mutation was not present in 300 normal chromosomes. To determine the functional significance of these findings, chlorothiazide-inhibitable 22Na uptake was measured in PBMC from control subjects, the parents, and the patients with GS in the presence of bumetanide. In control PBMC, chlorothiazide inhibited 22Na uptake by approximately 9%. PBMC from the two patients with GS failed to respond to chlorothiazide. These results demonstrate that PBMC can be used for mutational analysis of NCCT mRNA in patients with GS. Furthermore, functional evidence is provided that the underlying cause of GS is defective NCCT NaCl cotransport.

Ruptured aneurysm of the ductus diverticulum into the pulmonary artery in a man: a successful repair

Aneurysm of the ductus diverticulum in the adult is rare and its rupture is fatal. A 75-year-old man presented with congestive heart failure that suddenly occurred with a continuous murmur. Angiography showed a left-to-right shunt through a large thrombosed aneurysm of the ductus diverticulum (6 cm), and the pulmonary-to-systemic flow ratio was 2.6. Patch closure of the orifice (3x4 cm) of the aneurysm and repair of the perforated pulmonary artery were done emergently under hypothermic cardiopulmonary bypass with selective cerebral perfusion. He recovered uneventfully. Early recognition and early intervention should be indicated in this otherwise fatal condition.

Mechanism and regulation of riboflavin uptake by human renal proximal tubule epithelial cell line HK-2

Riboflavin (RF), a water-soluble vitamin, is essential for normal cellular functions, growth, and development. Normal RF body homeostasis depends on intestinal absorption and recovery of the filtered vitamin in renal tubules. The mechanism and cellular regulation of the RF renal reabsorption process, especially in the human situation, are poorly understood. The aim of this study was therefore to address these issues, using a recently established human normal renal epithelial cell line, HK-2, as a model. Uptake of RF by HK-2 cells was found to be 1) linear with time for 5 min of incubation and occurring with minimal metabolic alterations, 2) temperature dependent, 3) Na+ independent, 4) saturable as a function of concentration [apparent Michaelis constant (K(m)) of 0.67 +/- 0.21 microM and maximal velocity (Vmax) of 10.05 +/- 0.87 pmol.mg protein-1.3 min-1], 5) inhibited by structural analogs and anion transport inhibitors, and 6) energy dependent. Protein kinase C-, protein kinase A-, and protein tyrosine kinase-mediated pathways were found to have no role in regulating RF uptake. On the other hand, a Ca2+/calmodulin-mediated pathway appeared to play a role in the regulation of RF uptake by HK-2 cells via an effect on the Vmax, as well as on the apparent K(m) of the RF uptake process. The uptake process of RF was also found to be adaptively regulated by the level of the substrate in the growth medium, with the effect being mediated through changes in the apparent K(m) and the Vmax of the uptake process. These results demonstrate that RF uptake by the human-derived renal epithelial cell line HK-2 is via a carrier-mediated system that is temperature and energy dependent and appears to be under the regulation of a Ca2+/calmodulin-mediated pathways and substrate level in the growth medium.