Bioanalytical calibration curves: variability of optimal powers between and within analytical methods

The objective of this study was to investigate the variability of optimal power models in contrast to common regression models within and between analytical methods, as well as the frequency of outlier rejection. This was done by fitting the power model to calibration curve data using the minimum sum of squared residuals as a curve selection criterion. The jackknife percent deviation was used for detecting outliers. The data were obtained from 2087 analytical batches for 91 projects using various analytical techniques. The most frequent regression model varied between analytical techniques while the median and interquartile range of the optimal powers were stable. Outlier rejection is highest in GC and LCMS in which the Wagner (Quadratic, log-log) is the most frequent model. These results suggest that the greatest source of variability in the ideal transformation may not be the analytical technique but other within-lab sources. Outlying values may be due to these other sources of variability as suggested by the outlier rejection profile.

G-->A substitution at position -75 of the apolipoprotein A-I gene promoter. Evidence against a direct effect on HDL cholesterol levels

The present study sought to resolve the contradictory evidence as to whether the G-->A substitution at position -75 of the apoA-I gene promoter raises HDL cholesterol (HDL-C) levels by examining the effect of this polymorphism in French Canadians, a relatively genetically homogeneous population. Among 308 women, carriers of the A allele displayed 12% and 10% higher mean plasma HDL-C and apoA-I concentrations, respectively, than did noncarriers. Among 345 men, no effect of the A allele was noted. The frequency distribution of HDL-C levels in women carrying the A but not the G allele appeared bimodal, with one peak corresponding to the mean of the noncarriers and a second to higher HDL-C. Thus it appears that only a subset of A alleles confers high HDL-C levels. This hypothesis was supported by data from four kindreds within which some but not all A alleles segregated with hyperalphalipoproteinemia. The data suggest that the A substitution in the apoA-I gene promoter does not directly confer high HDL-C levels but may be in linkage disequilibrium with other sequence polymorphism(s) at this locus in a subset of alleles that raise HDL-C levels.

Evidence for a cholesterol-lowering gene in a French-Canadian kindred with familial hypercholesterolemia

We describe a four-generation kindred with familial hypercholesterolemia (FH) in which two of the eight heterozygotes for a 5-kb deletion (exons 2 and 3) in the low density lipoprotein (LDL) receptor gene were found to have normal LDL-cholesterol levels. In our search for a gene responsible for the cholesterol-lowering effect in this family, we have studied variation in the genes encoding the LDL receptor, apolipoprotein (apo) B, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, apoAI-CIII-AIV, and lipoprotein lipase. The analysis showed that it was unlikely that variation in any of these genes was responsible for the cholesterol-lowering effect. Expression of the LDL receptor, as assessed in vitro with measurements of activity and mRNA levels, was similar in normo and hyperlipidemic subjects carrying the deletion. Analysis of the apo E isoforms revealed that most of the e2 allele carriers in this family, including the two normolipidemic 5-kb deletion carriers, were found to have LDL-cholesterol levels substantially lower than subjects with the other apo E isoforms. Thus, this kindred provides evidence for the existence of a gene or genes, including the apo e2 allele, with profound effects on LDL-cholesterol levels.

New methods for rapid detection of low-density lipoprotein receptor and apolipoprotein B gene mutations causing familial hypercholesterolemia

Due to a genetic founder effect, five mutations in the low-density lipoprotein receptor gene account for approximately 83% of familial hypercholesterolemia (FH) diagnosed in French-Canadians. The most frequent mutation, present in 61% of heterozygotes, is a > 10 kb deletion of the 5' region of the gene that removes the promoter and the first exon, resulting in a null allele. Other less prevalent mutations include a gene deletion of approximately 5 kb, which removes exons 2 and 3 (2% of cases) and three missense mutations: Trp66-->Gly (exon 3) (12%), Glu207-->Lys (exon 4) (3%), and Cys646-->Tyr (exon 14) (6%). The apoB Arg3500-->Gln mutation was absent in 228 French Canadians with the FH phenotype. Taking advantage of the availability of fluorescent DNA detection, we have substantially improved the assays for these mutations.

Prevalence of alleles encoding defective lipoprotein lipase in hypertriglyceridemic patients of French Canadian descent

It has previously been estimated that due to genetic "founder effects," 97% of lipoprotein lipase (LPL) gene alleles conferring type I hyperlipoproteinemia (HLP) in French Canadians encode one of the following mutant LPL forms: Gly188-->Glu, Pro207-->Leu, or Asp250-->Asn. Although the genetic basis of type I HLP is known to be homozygosity for LPL deficiency, that for other forms of HLP, especially types IV, and V HLP, is not clear. It is also unclear whether hypertriglyceridemia due to very low density lipoprotein (VLDL) overproduction can be distinguished phenotypically from that due to defective catabolism of plasma lipoprotein triglycerides. The present study took advantage of the unique circumstances inherent in the relatively genetically isolated French Canadian population to address these questions. This study was carried out in order to determine the prevalence of these three mutant LPL alleles, and of a fourth encoding LPL Asn291-->Ser, in French Canadian patients with hypertriglyceridemia. The prevalence of heterozygosity for one of the four LPL mutant alleles in nondiabetic, nonobese hypertriglyceridemic subjects was 16 of 95 type IV HLP (17%) and 4 of 26 type V HLP cases (15%). These alleles were not found in over 150 normotriglyceridemic subjects, supporting the likelihood that the mutant alleles were at least partially responsible for HLP. In addition, heterozygosity for LPL deficiency due to one of these mutations apparently did not contribute to hypoalphalipoproteinemia, and was observed in 3 of 39 subjects with type III HLP. The results suggest that in French Canadians, 15-20% of type IV and V HLP cases are associated with these genetic defects in plasma triglyceride catabolism.

Comparison of two parathyroid hormone assays for the rat: the new immunoradiometric and the older competitive binding assay

A competitive binding assay for parathyroid hormone (PTH INS) has been used since 1986 to measure PTH in rats. During the past year an immunoradiometric assay for the measurement of PTH (PTH IRMA) in the rat was developed. The purpose of the present study was to compare results obtained with the PTH INS and IRMA and to provide a framework for comparison for investigators who have used the PTH INS in previous studies. A total of 99 rats were studied; 27 rats had normal renal function, and 72 rats had surgically induced renal failure. In the azotemic rats, the magnitude of hyperparathyroidism was varied by changing the calcium and phosphorus composition of the diet. The correlation between the two PTH assays in the 99 rats was r = 0.98, p < 0.001. For the 27 rats with normal renal function, the correlation even within the narrow range of normal PTH values was significant, r = 0.71, p < 0.001. In the 72 azotemic rats, in which the highest INS PTH value was approximately 17 times normal, the correlation between the two PTH assays was r = 0.98, p < 0.001. The PTH IRMA provides distinct advantages, such as extended standard range, shortened incubation time, increased sensitivity, and technical simplicity, but our results indicate that the PTH INS provided an accurate measurement of PTH. Furthermore, our results should provide investigators who have used the PTH INS in previous studies with a framework for comparison with studies in which the PTH IRMA was used.

Nuclear matrix protein mitotin messenger RNA is expressed at constant levels during the cell cycle

During the course of an investigation on nuclear matrix protein cDNAs, we have isolated a cDNA clone hybridizing with the messenger RNA encoding mitotin. Mitotin is a 125 kDa/pI 6.5 nuclear matrix protein present in proliferating but not in resting cells. This protein was shown to have a marked increase and characteristic redistribution in G2/M phase of the cell cycle. In this report, using synchronized Raji and WISH cells, we demonstrate that mitotin messenger RNA is expressed at the same level throughout the cell cycle.

[Fixed partial denture on osseointegrated screw implants]

There are many differences between full dentures on Brånemark implants and fixed partial dentures built on the same type of implants: due to some more critical anatomical conditions, the choice of number, position and length of the implants is more delicate; the need of an harmonious crown-gingival tissue relationship; higher occlusal forces than in edentalous cases; difficulty in satisfying aesthetic requirements and ease of hygiene. The surgical treatment plan, a pre-requesite to any surgery, permits to determine the length of implants, their number, their position, their long axis direction and the design of the surgical guide, which will indicate to the surgeon the location and the axis for drilling. If this axis is nearly parallel to the sagittal plane for mandibular implants, it will be angulated to that same plane for maxillary implants. In the latter cases, it is often necessary to use angulated transepithelial abutments in order to prevent the abutment screw from having an occlusal access. In order to perform the prosthetis, an impression should be taken with the transepithelial abutments. The final reconstruction can be preceded by a temporary prosthesis, then (or) transitory to await gingival stabilization and not overload the implant immediately after it has been connected with the abutment. The fixed partial denture can be secured with screws or cemented when it is of small size and it must satisfy the functional and aesthetic requirements of the patient. The choice of the material used on the occlusal surface is very important and varies depending on the case. Aesthetics should not be prevent an in easy hygiene. These objectives are not reached at the time the prosthesis is made but during the course of the surgical and prosthetic treatment. Single restorations are subjected to the rules pertaining to any fixed partial denture on implants, but have particular characteristics, such as the almost systematic elimination of the abutment and the absolute necessity of the correct placement of the implant. The single units are more easily subject to unscrewing for mechanical reasons. Although the use of implants is a valuable aid in cases of partial fixed restoration, it requires particular attention with regard to precision.

Non small cell lung carcinoma (NSCLC) at stage 3. A fourteen years retrospective study of 449 patients. Indications of surgery in a multidisciplinary management

Through a fourteen years retrospective study of all the patients treated at the State University of Liège, we have focused on the survival of 449 patients with, at least, a clinical stage 3 NSCLC disease (NORMS UICC). The whole study was divided in two periods (1972-1978, period 1, and 1979-1985, period 2) because, everything remaining nearly equal as far as the clinical material was concerned, period 2 was characterized by a different therapeutic attitude. Since 1979, the NSCLC stage 3's surgical indications have been widely extended. We have performed surgical resections in patients with NSCLC N2 disease because of positive homolateral mediastinal lymph nodes or with T3 disease. This led the NSCLC stage 3 resection rate to move from 26% in period 1 to 47% in period 2. We report here the effects of such a management on the short and long term survival and the stage 3 NSCLC global prognosis. We noted a modest significant increase in the NSCLC stage 3 global prognosis with a five year survival of 4% and 6% (period 1 and 2 respectively; P = 0.03). The 172 resected patients' outcome did not change (five year survival 11% (P1) and 12% (P2]. Although patients were not randomized, our results suggest that adjuvant therapy should not be added whenever the patient underwent a complete resection. On the other hand, it seems very useful indeed whenever the resection was partial. NSCLC patient at stage 3 who underwent a complete resection achieved a 37% five years survival.

The effect of alpha-naphthylisothiocyanate on bile secretion prior to and during the onset of cholestasis in the rat

The effect of alpha-naphthylisothiocyanate (ANIT) on bile flow, erythritol clearance, bile acid excretion and bilirubin excretion was studied in rats. The median time-to-effect (Et50) for the appearance of cholestasis was about 15 h. ANIT failed to exert a gradual effect on bile flow or erythritol clearance before the onset of cholestasis. However, 3 h before complete cessation of bile flow, a rapid decline in bile flow and bile acid excretion was observed. Bile acid-independent flow was markedly reduced. However, the bile acid-dependent component was also affected.

Comparison of levels of cytosol estrogen receptors with "arterial" and "venous" concentrations of gonadic steroids in mammary tumors

Plasma steroid concentrations measured in the post-menopausal women with breast cancer showed a close correlation between the various androgens. The post-menopausal women exhibited a correlation between estrogen receptors (ER) and "arterial" 17 alpha-hydroxyprogesterone levels in the breast. ER levels expressed as a function of plasma (arterial) steroid (P/17 P) molar concentration ratio were distributed within a hyperbola, suggesting the existence of a control mechanism for breast cell ER levels.

Induction of beta 1-receptors for kinins in the rabbit by a bacterial lipopolysaccharide

The intravenous injection of 10 microgram of a lipopolysaccharide extracted from E. Coli to rabbits leads to the appearance of a hypotensive effect for des-Arg9-BK and increases significantly the vasodilator effect of this peptide in isolated hearts and its contractile effects in strips of large arteries and veins. LPS elicits these responses when administered 5 or 20 h before anesthesia; the hypotensive response of animals receiving LPS just before anaesthesia is similar to that of untreated rabbits. All actions of des-Arg9-BK in vivo, in isolated hearts and in isolated tissues are blocked by des-Arg10,[Leu9]-kallidin (KD), a specific inhibitor of kinins B1-receptor. These data are taken as evidence of the appearance of B1-response to kinins in the few hours following LPS injection. The response of the animals, perfused organs and isolated tissues to other agonists, such as substance P or [Tyr(Me)8]-BK (an activator of B2-receptors for kinins) are not affected by the treatment with LPS nor are they modified by the antagonist des-Arg10,[Leu9]-KD. The present data, together with previous studies on the sensitization mechanism of B1-receptor containing preparations, suggest that LPS induces the formation of B1-receptors in the rabbit, within a few hours. The activation of B1-receptors by des-Arg9-BK produces hypotension, coronary vasodilation and stimulation of large arteries and veins isolated and suspended in vitro. Some large arteries and veins (e.g. the aorta and the anterior mesenteric vein) as well as some peripheral vascular beds (e.g. the coronary vessels) have the ability of generating B1-receptors, while other organs (e.g. the external jugular vein) have not or very little. The reason for this phenomenon as well as the intimate mechanism by which LPS induces the formation of B1-receptors remain to be elucidated.

[Use of a mounting table for arbitrary hinge transfer on an articulator]

The use of a mounting table allowing arbitrary hinge axis transfer on a semi-adjustable articulator is described. Following this method an accurate stabilization can be expected. This may prevent errors during the mounting of maxillary models.

[Presentation of a universal face-bow]

A universal face bow is reported for transferring an arbitary or located hinge axis on most articulators. Its use is simple and safe due to the rigidity of the assemblies during every step of the transfer.

[A new modular semi-adaptable articulator]

A new semi-adjustable Arcon articulator is reported. It is an evolutive device that can be set with two different types of condylar housings. - A Type: adjustable condylar guidance, preadjusted Bennett angle at 13 degrees - B Type: adjustable condylar guidance, adjustable Bennett angle. It is possible to set on this B type fossa assembly another Bennett wing with an adjustable immediate side shift This device has a double lock in centric relation and may be set with an arbitrary or localized hinge axis.

[The centric relation. IV. Variations in condylar positions according to the methods of measuring centric relation and to the patient's clinical type]

When recording and transferring centric relation onto an articulator errors can be minimized by proper use of dental materials. Remaining errors may be due to either the patient or the clinician. 3 recording techniques (Lucia, Dawson, Ramfjord) are being tested by 2 operators on 12 patients. In order to get a proper centric relation one must not rely upon a technique of taking it but rather on an adequate clinical evaluation of the TMJ at that moment. The role of inadequate intermaxillary relationship upon painful TMJ syndroms cannot be underestimate.

Specific inhibition of the incorporation of tritiated thymidine in regenerating rat liver by a rat hepatocytes supernatant

Studies on endogenous inhibitors obtained from supernatant fluids of rat hepatocytes indicated that the supernatant arrests the normal cell cycle at two points, namely, before the beginning of the S phase and at the onset of metaphase when assayed in regenerating liver cells in situ. The specificity of this (these) inhibitory substance(s) was evidenced by the finding that no inhibition of cell division was observed in situ in tongue, intestine, or kidneys of animals injected with concentrations of the hepatocyte supernatant that inhibited cell division in regenerating liver. When higher concentrations of the inhibitor-containing supernatant were used, only the tongue epithelial cells were affected in addition to the regenerating liver cells.

[The centric relation. III. Usefulness of 3 interocclusal registration materials during mounting of the models on an articulator]

3 waxes commonly used to record interocclusal positions are tested on an articulator. All recordings are made at the same opening and the condylar variations are analysed with a Buhnergraph. Soft materials may induce errors and relining the interocclusal records allows a higher degree of accuracy.

[Study of the linear variation in certain dental plasters and self-polymerizing resins]

Dental plasters and self-curing acrylic resins are tested. One must pay attention to the setting expansion of plasters and to the setting contraction of acrylic resins which may be very important if these materials are used without care.