Chemical Nature of Agrocin 84 and Its Effect on a Virulent Strain of Agrobacterium tumefaciens

Agrocin 84, produced by Agrobacterium radiobacter K84, inhibited ribonucleic acid, deoxyribonucleic acid, and protein synthesis and amino acid transport in a susceptible, virulent strain of A. tumefaciens H-38-9. Cell motility was immediately stopped by action of the agrocin, 50% of the cells were killed within 15 min of contact, and the remainder were inhibited. Agrocin 84 is trypsin and pepsin resistant, but chemical analysis indicated a small peptide with a molecular weight of 2,500 containing six different amino acids, including nine molecules of glutamine or glutamic acid and seven molecules of serine.     

ASSAY OF LIGNOCAINE IN LAEVULOSE INFUSION BY SECOND DERIVATIVE UV SPECTROSCOPY*

Lignocaine and laevulose infusion is sterilized by autoclaving. On exposure to heat, laevulose partially degrades to 5-hydroxymethylfurfural (5-HMF), which has a Λ_max value at 284 nm in the UV spectrum. This overlaps the spectrum of lignocaine hydrochloride, for which the Λ_max values are 264 nm and 271 nm. An assay based on second derivative spectroscopy has been developed for the lignocaine content, free from the influence of 5-HMF.     

Liquid-chromatographic separation of urinary 5-hydroxy-3-indoleacetic acid, with measurement at 254 nm

A "high-performance" liquid-chromatographic procedure for 5-hydroxy-3-indoleacetic acid is described and compared with a colorimetric method in which 1-nitroso-2-naphthol is used. The analyte and an internal standard, p-nitrobenzoic acid, were extracted into diethyl ether from urine at pH 4.0 (acidified with HCl) to which sodium chloride had been added, and the ether was back-extracted with acetate buffer, pH 9.2. Aliquots of this extract were injected into a reversed-phase liquid-chromatographic column and eluted with pH 3.5 acetate buffer/methanol (95/5 by vol); the effluent was monitored at 254 nm. The precision (CV) of the method was 11.8% at 1.8 mg/L, 5.5% at 92 mg/L. Analytical recovery averaged 84%. The colorimetric method gave higher values for the analyte than did the chromatographic method for all patients' urines.     

Assessment of the fixation stiffness of some femoral stems of different designs

BACKGROUND: Appropriate contour design of a femoral stem is important for the secure primary fixation. Although the relationship between the contour and stress or micro-motion at the fixation site has been analyzed, guidelines on stem design have not been established. METHODS: Different kinds of finite element models of three femoral stems were constructed for computer simulation. These models had the contour designs that head for the tight mechanical fixation by the different ways, respectively. Boundary and initial conditions were (i) rigid contact of the distal end of the model femur with the rigid base. (ii) Stepping load of 800 N or 1800 N was applied to the proximal top of the stem. (iii) Stepping load of 640 N or 1440 N was pulled from the greater trochanter of the femur as muscle force. The ratio of displacement to the vertical load, which was defined as fixation stiffness, was calculated. FINDINGS: The mean displacement of the intra-medullary cruciate stem was 27.6 nm. For the VerSys stem with sharp fins, the mean displacement was 32.9 nm. For the PerFix SV stem with a flange, the mean displacement was 52.8 nm. Vertical fixation stiffness estimated on the intra-medullary cruciate stem, the VerSys stem, and the PerFix SV stem was 461, 264, and 313 MN/mm, respectively. INTERPRETATION: Contour design of a femoral stem is important for achieving secure fixation, which prevents loosening. We introduce fixation stiffness as a measure to theoretically evaluate the primary fixation of femoral stems.     

An assessment on crystallization phenomena of Si in Al/a-Si thin films via thermal annealing and ion irradiation

In the present study, crystallization of amorphous-Si (a-Si) in Al/a-Si bilayer thin films under thermal annealing and ion irradiation has been investigated for future solar energy materials applications. In particular, the effect of thickness ratio (e.g. in Al : a-Si, the ratio of the Al and a-Si layer thickness) and temperature during irradiation on crystallization of the Si films has been explored for the first time. Two sets of samples with thickness ratio 1 : 1 (set-A: 50 nm Al/50 nm a-Si) and thickness ratio 1 : 3 (set-B: 50 nm Al/150 nm a-Si) have been prepared on thermally oxidized Si-substrates. In one experiment, thermal annealing of the as-prepared sample (of both the sets) has been done at different temperatures of 100 °C, 200 °C, 300 °C, 400 °C, and 500 °C. Significant crystallization was found to initiate at 200 °C with the help of thermal annealing, which increased further by increasing the temperature. In another experiment, ion irradiation on both sets of samples has been carried out at 100 °C and 200 °C using 100 MeV Ni⁷⁺ ions with fluences of 1 × 10¹² ions per cm², 5 × 10¹² ions per cm², 1 × 10¹³ ions per cm², and 5 × 10¹³ ions per cm². Significant crystallization of Si was observed at a remarkably low temperature of 100 °C under ion irradiation. The samples irradiated at 100 °C show better crystallization than the samples irradiated at 200 °C. The maximum crystallization of a-Si has been observed at a fluence of 1 × 10¹² ions per cm², which was found to decrease with increasing ion fluence at both temperatures (i.e. 100 °C & 200 °C). The crystallization of a-Si is found to be better for set-B samples as compared to set-A samples at all the fluences and irradiation temperatures. The present work is aimed at developing the understanding of the crystallization process, which may have significant advantages for designing crystalline layers at lower temperature using appropriate masks for irradiation at the desired location. The detailed mechanisms behind all the above observations are discussed in this paper.

In the present study, crystallization of amorphous-Si (a-Si) in Al/a-Si bilayer thin films under thermal annealing and ion irradiation has been investigated for future solar energy materials applications.     

A procedure for determining the oxidative modification of apolipoproteins in low-density lipoproteins

The purpose of the present study was to develop a new procedure for estimating the oxidative modification of apolipoproteins in low-density lipoproteins (LDLs). The procedure was developed to use blood serum from 153 males aged 45-65 years, including 69 patients with coronary angiography-verified coronary atherosclerosis and 84 males from a representative sample from Novosibirsk residents of the same age. The new procedure is as follows: a rapid method for isolating serum LDLs, their apolipoprotein (apoLP) protein measurement by the Lowry procedure, their precipitation, a reaction with 2,4-dinitrophenylhydrazine in 2 M HCl solution, by subsequently rinsing in the ethanol:ethyl acetate (1:1) solution, dissolving the precipitate in 8 M urea, and by determining the level of the resultant dinitrophenylhydrazones by spectrophotometry at 363 nm, followed by conversion to LDL concentration of apoLP. The procedure is of informative value for the degree of oxidative LDL modification of apoLP under oxidative stress; it is technically simple, takes little time, and shows a good reproducibility. The values of determined oxidized LDL apoLP by the developed procedure highly positively correlated with the estimates of an oxidized total blood protein fraction and with the values of endothelial dysfunction and did not with the parameters of blood LDL peroxidation. The detected elevated oxidation LDL apoLP in males with coronary atherosclerosis suggests that this index is an additional marker of potentially atherogenic LDL changes.     

Degradable polyethylenimine-alt-poly(ethylene glycol) copolymers as novel gene carriers.

An ideal gene carrier requires both safety and transfection efficiency. Polyethylenimine (PEI) is a well-known cationic polymer, which has high transfection efficiency owing to its buffering capacity. But it has been reported that PEI is cytotoxic in many cell lines and non-degradable. In this study, we synthesized degradable PEI-alt-poly(ethylene glycol) (PEG) copolymers using Michael-type addition reactions as a new gene carrier and characterized them. These copolymers were complexed with plasmid DNA and the resulting complexes were characterized by dynamic light scattering, gel retardation and atomic force microscopy to determine particle sizes, complex formation and complex shape, respectively. Cytotoxicity and transfection efficiency of the copolymers were also checked in cultured HeLa human cervix epithelial carcinoma cells, HepG2 human hepatoblastoma cell line and MG63 human osteosarcoma cells. PEG to PEI ratio in the copolymers was near 1 and the molecular weight of the copolymer ranged from around 8000 to 12,900. These copolymers degraded rapidly at 37 degrees C in 0.1 M phosphate buffered saline (PBS, pH 7.4). The complete copolymer/DNA complex was formed at an N/P ratio of 12, producing a complex resistant to DNase I. Particle sizes decreased with increasing N/P ratio and PEG molecular weight, exhibiting a minimum value of 75 nm at an N/P ratio of 45 with PEI-alt-PEG (700). Cytotoxicity study showed that copolymers exhibited no cytotoxic effects on cells even at high copolymer concentration. Also, transfection efficiency was influenced by PEG molecular weight and, in case of PEI-alt-PEG (258), the transfection efficiency was higher than that for PEI 25 K in HepG2 and MG63, whereas it was lower than that for PEI 25K in HeLa cells.     

Effect of weight loss with lifestyle intervention on risk of diabetes

OBJECTIVE: Diabetes Prevention Program (DPP) participants randomized to the intensive lifestyle intervention (ILS) had significantly reduced risk of diabetes compared with placebo participants. We explored the contribution of changes in weight, diet, and physical activity on the risk of developing diabetes among ILS participants. RESEARCH DESIGN AND METHODS: For this study, we analyzed one arm of a randomized trial using Cox proportional hazards regression over 3.2 years of follow-up. RESULTS: A total of 1,079 participants were aged 25-84 years (mean 50.6 years, BMI 33.9 kg/m(2)). Weight loss was the dominant predictor of reduced diabetes incidence (hazard ratio per 5-kg weight loss 0.42 [95% CI 0.35-0.51]; P < 0.0001). For every kilogram of weight loss, there was a 16% reduction in risk, adjusted for changes in diet and activity. Lower percent of calories from fat and increased physical activity predicted weight loss. Increased physical activity was important to help sustain weight loss. Among 495 participants not meeting the weight loss goal at year 1, those who achieved the physical activity goal had 44% lower diabetes incidence. CONCLUSIONS: Interventions to reduce diabetes risk should primarily target weight reduction.     

超声诊断艾滋病患者感染性心内膜炎

目的 探讨艾滋病(AIDS)合并感染性心内膜炎患者彩色多普勒超声心动图特征。 方法 观察227例AIDS合并感染性心内膜炎患者彩色多普勒超声心动图,结合临床资料和实验室检查结果进行回顾性分析。 结果 227例患者心脏各瓣膜、室壁、房室间隔内膜面均有不同程度增厚、毛糙和赘生物形成,以右心心内膜炎最常见。病原微生物种类以细菌、真菌感染为主,可为混合性感染。通过内科抗感染治疗,赘生物84例(37.00％,84/227)消失,79例(34.80％,79/227)缩小,64例(28.19％,64/227)变化不大,但回声增强、活动度减少。 结论 AIDS合并感染性心内膜炎患者的超声心动图有特征性的改变,可为临床诊断、治疗提供有价值的信息。     

Intravascular Extraction of Chronic Pacemaker Leads: Efficacy and Follow-Up

Extraction of chronic pacemaker leads has been recommended for infections, prevention of venous thrombosis, migration, and possible perforation. Success with constant traction techniques has been variable, and the cost and morbidity of open chest surgical procedures are prohibitive. Efficacy of a new system for lead extraction using intravascular techniques was analyzed. The system (Cook Pacemaker) uses a locking stylet, which is secured at the distal electrode by counterclockwise rotation to reinforce the lead and facilitate traction, and dilator sheaths that are used to free the lead from adhesions in the venous system. In a series of 56 patients (ages 19–88)who presented for lead extraction because of erosion (5), infection (14), lead replacement (35), or other (2), 86 leads were extracted. Thirty-two were atrial leads and 54 ventricular; 23 had active fixation and 63 passive. Average duration of implant was 58 ±42 months (range 1–264). Eighty-four leads were totally removed and two partially removed. For these two leads, the distal tip was not removed; in both cases the locking stylet was not secured at the distal electrode due to obstruction within the lead. Two patients developed arm edema following the procedure, which resolved with elevation. One patient developed a subclavian thrombosis, which resolved with warfarin anticoagulation. Four patients have expired due to unrelated causes. In conclusion, this intravascular approach for extraction of chronic leads is effective, and the procedure is safe when performed by experienced personnel.     

An N-terminal molecular form of parathyroid hormone (PTH) distinct from hPTH(1 84) is overproduced in parathyroid carcinoma

BACKGROUND: A new parathyroid hormone (PTH) species, the N-terminal PTH form (N-PTH), is distinct from intact human PTH of 84 amino acid residues [hPTH(1-84)] and is recognized in a 3rd-generation assay of "whole" PTH (wPTH; the 1-2 epitope) but not in a 2nd-generation assay of "total" PTH (tPTH; the 12-18 epitope). N-PTH usually represents <15% of wPTH but can be overproduced in severe primary hyperparathyroidism (PHPT) and secondary hyperparathyroidism. We investigated whether N-PTH is also overproduced in parathyroid cancer and whether N-PTH concentration is influenced by calcimimetic therapy. METHODS: We studied 8 patients with parathyroid carcinoma before and at week 16 of cinacalcet therapy, 6 patients with PHPT, and 6 control individuals. We fractionated sera with HPLC and analyzed fractions with the 2 assays to quantify hPTH(1-84), N-PTH, and non-(1-84) PTH fragments. RESULTS: Half of parathyroid carcinoma patients had an increased wPTH:tPTH ratio [mean (SD), 1.35 (0.29)]; the others had a typical ratio [0.72 (0.12)]. HPLC fractionation of sera from 2 high-ratio patients confirmed N-PTH overproduction [65% (12%) of wPTH]. The N-PTH fraction was <15% of wPTH in PHPT and healthy individuals. Calcimimetic therapy appreciably reduced calcium concentrations in parathyroid carcinoma patients but had little influence on PTH concentration, the wPTH:tPTH ratio, or the PTH HPLC profile. CONCLUSION: N-PTH is overproduced in some parathyroid cancer patients, but calcimimetic therapy does not influence its production. The clinical implications of this finding in parathyroid carcinoma await additional studies with an emphasis on N-PTH's biological activity and with larger numbers of patients.     

How is deep vein thrombosis diagnosed and managed in UK and Australian emergency departments?

Background: Recent research has identified technologies that may be of value in the diagnosis and management of deep vein thrombosis (DVT). We aimed to survey current practice in the United Kingdom (UK) and Australia to determine the extent to which these technologies have been implemented in these two healthcare systems. Methods: We undertook a postal survey of 255 hospitals in the UK and 89 hospitals in Australia, requesting details of individual diagnostic tests, use of diagnostic algorithms, and management of DVT. Results: We received replies from 186/255 UK hospitals (73%) and 84/89 of Australian hospitals (94%). Ultrasonography and laboratory based D-dimer were the most commonly available tests. We received 43 different algorithms from 51 hospitals. With only a very few exceptions, DVT diagnosis was ruled in by positive venography or positive ultrasound without venographic confirmation. By contrast a variety of different criteria were used to rule out DVT. Most algorithms used a combination of low clinical risk and negative D-dimer to rule out DVT, but some required all patients to receive ultrasound or venography. Few ruled out on the basis of low clinical risk or negative D-dimer alone. Low molecular weight heparins were overwhelmingly the treatment of choice for established DVT. Most departments (214/264; 81%) offered outpatient treatment. Conclusion: Recently developed technologies for the diagnosis and treatment of DVT have been widely implemented in the UK and Australia. Variation in practice, and thus presumably uncertainty, seems to be greatest in relation with the criteria used to rule out DVT.     

Fabrication of polytetrafluoroethylene nanofibrous membranes for guided bone regeneration

In this study, we first prepared the precursor polytetrafluoroethylene (PTFE)/poly(ethylene oxide) (PEO) nanofibrous membranes by electrospinning with different PTFE/PEO weight ratios. These membranes exhibited three-dimensional interconnected pore structures. The average diameter of the precursor nanofibres decreased with increased PTFE contents from 633 ± 34 nm (PTFE/PEO weight ratio of 5 : 1) to 555 ± 63 nm (PTFE/PEO weight ratio of 7 : 1) because of the decrease in solution viscosity. Then, the precursor membranes were sintered with different temperatures to obtain the PTFE nanofibrous membranes, resulting in the average diameter of the nanofibres increasing from 633 ± 34 nm to 947 ± 78 nm with the increase in sintering temperature; consequently, the membrane became more compact. This compaction caused a decrease in porosity from 76.5 ± 2.9% to 69.1 ± 2.6% and an increase in water contact angle from 94.1 ± 4.2° to 143.3 ± 3.5°. In addition, the mechanical properties of the PTFE nanofibrous membranes increased with increasing sintering temperature. Cytocompatibility test results revealed that the PTFE350 membrane, which was sintered at 350 °C, promoted the proliferation and differentiation of MC3T3-E1 cells more rapidly than other membrane types. These results suggested that the PTFE nanofibrous membranes could be ideal biomaterials in tissue engineering for bone regeneration.

In this study, PTFE nanofibrous membranes were fabricated by sintering the previously electrospun polytetrafluoroethylene (PTFE)/poly(ethylene oxide) (PEO) nanofibrous membranes.     

A simple spectrophotometric assay of plasminogen activator: comparison with the fibrinolytic method

We describe a simple assay of plasminogen activator in which the enzyme reacts with a mixture of plasminogen and H-D-valyl-L-leucyl-L-lysine-p-nitroanilide for 1 h at 37 degrees C after which the absorbance is measured at 405 nm. The method detects as little as 2 CTA milliunits of activator and is linear over a 100-fold range of enzyme concentration. The new procedure has been used successfully for the assay of activator in breast tumor cytosols, cell culture supernatants, and pleural or ascitic fluids. Thirty-two biological samples have been assayed for plasminogen activator activity with both the spectrophotometric method and a classical fibrinolytic technique using radiolabeled fibrin. Although the two series of results are significantly correlated, the activities measured with the former assay are significantly different from those determined with the latter. It is shown that the spectrophotometric method is, in many respects, superior to the fibrinolytic procedure.     

Characterization of poly((N-trimethylammonium) ethyl methacrylate)-based gene delivery systems

We have synthesized a hydrophilic cationic homopolymer of N-trimethylammonium ethyl methacrylate chloride (pTMAEM) and its copolymers with 1-vinyl-2-pyrrolidone (VP) and methyl methacrylate (MMA) at various monomer ratios and examined the physicochemical and biological characteristics of polymer/DNA complexes. All the (co)polymers were able to condense DNA to small particles and protect it from nuclease degradation. The particle size of pTMAEM/DNA complexes was smaller (550-175 nm) than the other polymers (1200-300 nm) tested. The zeta potential of the complexes was increased with increasing (co)polymer/DNA weight ratios and reached the constant value. The plateau value slightly decreased from +28 mV to +21 mV (P > 0.05) when the monomer content was increased. The optimal transfection efficiency of pTMAEM/DNA (655 mU/mg protein) was found at 0.5 polymer/DNA weight ratio and was reduced with increasing weight ratios due to increased cytotoxicity. The maximum transfection efficiency of copolymer/DNA was observed at a weight ratio of one and transfection efficiency slightly decreased with increasing monomer content in the copolymers. Overall, pTMAEM-VP/DNA complexes showed reduced cytotoxicity and increased transfection efficiency as compared with the other (co)polymers tested.     

Weaning from mechanical ventilation in pediatric intensive care patients

Objective: The development of weaning predictors in mechanically ventilated children has not been sufficiently investigated. The purpose of this study was to evaluate the accuracy of some weaning indices in predicting weaning failure. Design: Prospective, interventional study. Setting: University-affiliated children's hospital with a 19-bed intensive care unit. Patients: 84 consecutive infants and children requiring mechanical ventilation for at least 48 h and judged ready to wean by their primary physicians. Interventions: Patients who met the criteria to start weaning underwent a trial of spontaneous breathing lasting up to 2 h. Bedside measurements of respiratory function were obtained immediately before discontinuation of mechanical ventilation and within the first 5 min of spontaneous breathing. The primary physicians were blinded to those measurements, and the decision to extubate a patient at the end of the spontaneous breathing trial or reinstitute mechanical ventilation was made by them. Failure to wean was defined as the requirement for mechanical ventilation at any time during the trial of spontaneous breathing (trial failure) or needing reintubation within 48 h of extubation (extubation failure). Measurements and main results: Seventy-five patients had neither signs of respiratory distress nor deterioration in gas exchange during the trial and were extubated. Twelve patients required reintubation within 48 h. In 9 patients, mechanical ventilation was reinstituted after a median duration of the spontaneous breathing trial of 35 min. The only independent predictor of trial failure was tidal volume indexed to body weight [odds ratio 2.60, 95 % confidence interval (CI) 1.40 to 24.9]. The only independent predictor of extubation failure was frequency-to-tidal volume ratio indexed to body weight (odds ratio 1.23, 95 % CI 1.11 to 1.36). The sensitivity, specificity, and positive and negative predictive values to predict weaning failure were calculated for each of the above variables. These values were 0.48, 0.86, 0.53, and 0.83, respectively, for a frequency-to-tidal volume ratio higher than 11 breaths/min per ml per kg and 0.43, 0.94, 0.69, and 0.83, respectively, for a tidal volume lower than 4 ml/kg. Conclusions: Three-quarters of ventilated children can be successfully weaned after a trial of spontaneous breathing lasting 2 h. Both tidal volume and frequency-to-tidal volume ratio indexed to body weight were poor predictors of weaning failure in the study population. Received: 20 February 1998 Accepted: 10 June 1998     

Prediction of infant birth weight by GDM screening tests. Importance of plasma triglyceride.

OBJECTIVE--We measured plasma glucose, GHb, GPro, IRI and TG at 24-28-wk gestation to determine the extent of elevations in GDM and relationships to glucose intolerance and infant macrosomia. RESEARCH DESIGN AND METHODS--Plasma samples were obtained 1 h after ingestion of 50 g glucose after an overnight fast in 521 randomly selected negative screenees, 264 positive screenees with GTT-, and 96 positive screenees with GTT+ (GDM). RESULTS--Screening test values in GDM subjects exceeded the GTT- group, whose values exceeded those of negative screenees: glucose, 9.6*, 8.7*, 6.3 mM; GHb, 5.2*, 4.9*, 4.7%; GPro, 3.1*, 3.0*, 2.8%; IRI, 791*, 662*, 410 pM; and TG, 2.3*, 1.9, 1.9 mM, (*P < 0.005 vs. negative screenees). TG was the only test elevated in the GDM but not in the GTT- groups. Screening test values correlated with GTT values in the following order (strongest to weakest): glucose* > TG* > GHb* > IRI > GPro (*statistical significance). Plasma TG was the only screening test significantly associated with birth weight corrected for gestational age (birth-weight ratio) (r = 0.09-0.16) (P < 0.05 to < 0.01) and was of the same order as 1- and 2-h GTT associations with birth weight (r = 0.13 and 0.14, respectively) (P < 0.05 to < 0.01). Plots of TG/birth-weight ratio increased linearly to the 80-90th TG percentile in negative screenees and GTT- subjects. GDM subjects followed this trend but with more variation. Above the 90th percentile for TGs, birth-weight ratio trended lower, significantly so when the groups were combined (P < 0.05). In multivariate analysis, TG was associated with birth-weight ratio even when maternal prepregnancy weight and pregnancy weight gain associations with TG and birth-weight ratio were controlled (P < 0.019). CONCLUSIONS--Of the five screening tests evaluated, all were elevated in GDM, but TG is the best discriminator of GDM from the GTT- group, and it is the only test significantly related to birth-weight ratio--and to glucose intolerance besides glucose itself. The TG association with birth weight is not explained fully by maternal weight. The results suggest that plasma TG may be a physiological contributor to infant birth weight. Further evaluation of plasma TG in GDM screening is justified, but GHb, GPro, and IRI appear to hold less promise.     

Induced hypocalcaemia controlled by a citrate clamp technique, and the intact parathyroid hormone response obtained

In order to investigate (1) the possibility of controlled induction and maintenance of hypocalcaemia, and (2) the intact parathyroid hormone (PTH(1-84)) response obtained thereby, 14 healthy individuals were administered an i.v. infusion of trisodiumcitrate. The reproducibility of the method established was assessed in five of the 14 individuals. Aiming at a steady-state level of blood ionized calcium (B-Ca2+) = 1.00 mmol/l, obtained within 30 min and subsequently maintained for 90 min, the infusion was guided by frequent determinations B-Ca2+. The method established was as follows: infusion of 0.85 mmol citrate/kg body weight/h during the first 10 min, followed by 0.44 mmol citrate/kg body wt h 1.26 exp. ((actual B-Ca2(+)--target B-Ca2+)/0.02) mmol/l, until B-Ca2+ = 1.00 mmol/l. In the steady-state period the infusion rate was 0.29 mmol citrate/kg body wt. h 1.26 exp. ((actual B-Ca2(+)--target B-Ca2+)/0.02) mmol/l. The method showed reproducibility by an overall difference in B-Ca2+ measurements of -0.03 mmol/l, which did not statistically differ from zero (p less than 0.05). No severe side effects were observed during a total of 21 infusions. Intact serum parathyroid hormone concentrations (S-PTH(1-84)) obtained during induced hypocalcaemia rose to a peak within 5-10 min, and then declined to a steady-state level about three times the initial. The serum (S) PTH(1-84) response could be caused by a burst of S-PTH(1-84) from a depot source while the steady-state level may indicate a stimulated secretion from parathyroid glands. The S-PTH(1-84) response was shown to be reproducible by an overall difference in S-PTH(1-84) measurements of -0.52 pmol/l, which did not statistically differ from zero (p less than 0.10).     

Influence of nutritional status on serum large N-truncated PTH, but not PTH(1-84) in hemodialysis patients.

BACKGROUND: Serum level of parathyroid hormone (PTH), measured by second-generation intact PTH (I-PTH), is known to be associated with nutritional status in hemodialysis (HD) patients. We investigated whether PTH(7-84) and larger N-truncated PTH or PTH(1-84) might be affected by nutritional status in HD patients. METHODS: Serum PTH was determined in 170 male HD patients by either a Bio-intact PTH (Bio-PTH) or I-PTH assay. Lean body mass in the trunk region was measured as a nutritional marker by dual X-ray absorptiometry. RESULTS: The serum PTH(7-84) level was theoretically obtained from the difference between serum I-PTH and Bio-PTH because I-PTH assay cross-reacted with PTH(7-84) with the same degree as PTH(1-84), although N-truncated PTH fragment larger than PTH(7-84) might affect theoretical serum PTH(7-84) level, although slightly. Serum PTH(1-84) was directly obtained from the serum Bio-PTH value because of its exclusive reaction with PTH(1-84). Serum PTH(7-84) correlated significantly with nutritional markers such as body weight, albumin, protein catabolic rate (PCR), TACBUN, BUN, phosphate, and lean body mass in the trunk, whereas PTH(1-84) correlated only with phosphate. Multiple regression analysis revealed that PCR, body weight, and lean body mass in the trunk region are significant factors independently associated with PTH(7-84), but not with PTH(1-84). CONCLUSIONS: The results suggest that serum levels of PTH(7-84) and larger N-truncated PTH fragments, but not PTH(1-84), might be affected by the nutritional state in HD patients, which might explain the reported correlation of serum I-PTH levels with nutritional markers.