Morning serum cortisol role in the adrenal insufficiency diagnosis with modern cortisol assays

PURPOSE

To investigate the accuracy of cutoff values of the morning serum cortisol (MSC) using the cortisol stimulus test (CST) insulin tolerance test (ITT) and 250 mcg short Synacthen test (SST) as the reference standard tests, to better define its clinical role as a tool in the diagnostic investigation of adrenal insufficiency (AI) AI.

METHODS

An observational study was conducted with a retrospective analysis of MSC in adult patients who had been submitted to a CST to investigate AI between January 2014 and December 2020. The normal cortisol response (NR) to stimulation was defined based on the cortisol assay.

RESULTS

371 patients underwent CST for suspected AI, 121/371 patients (32.6%) were diagnosed with AI. ROC curve analysis showed an area under the curve (AUC) for MSC of 0.75 (95% CI 0.69 - 0.80). The best MSC cutoff values to confirm AI were < 3.65, < 2.35 and < 1.5 mcg/dL with specificity of 98%, 99%, and 100%, respectively. MSC > 12.35, > 14.2 and > 14.5 mcg/dL had sensitivity of 98%, 99%, and 100%, respectively, being the best cutoff values to exclude AI. Almost 25% of patients undergoing CST for possible AI had MSC values between < 3.65 mcg/dL (6.7% of patients) and > 12.35 mcg/dL (17.5% of patients), making the formal CST testing unnecessary if we consider these cutoff values.

CONCLUSION

With the most modern cortisol assays, MSC could be used as a diagnostic tool, with high accuracy to confirm or exclude AI, avoiding unnecessary CST; thus, reducing expenses and safety risks during AI investigation.

Turn-on, photostable, nontoxic and specific, iron(II) sensor

The pressing need to develop a specific analytical sensor that can identify and quantify Fe(II) without a cytotoxic response was the major motivation drive in this work. The turn-on fluorescent sensor here described can successfully detect Fe(II) and discriminate this ion from other analytes that commonly act as interferents in biological media. Moreover, this reduced fluoresceinamine-based sensor has a high photostability and high dissociation constant, which is an indication that the complex obtained between reduced fluoresceinamine (RFL) and Fe(II) is highly stable. This fluorescence-based sensor has a binding mechanism of 1:1 and a positive cooperativity was found between analyte and sensor. The detection, quantification and sensitivity parameters of the sensor were determined: 21.6 ± 0.1 μM; 65.6 ± 0.1 μM and 48 ± 3 (×10⁷) μM, respectively. To evaluate a possible cytotoxicity effect an erythrocyte assay was performed and the obtained data were evaluated considering CdTe Quantum Dots (QDs) passivated with mercaptoacetic acid has experimental control. According to the resulting data RFL is not cytotoxic even when used in high concentrations, 660 mM. On the other hand QDs are quite different. Indeed it was proven that these heavy metal-based nanoparticles are responsible for 40% erytrocytes hemolysis in concentrations of 600 mM.

Virtual bronchoscopy for evaluating cervical tumors of the fetus

We report on four cases of fetal cervical tumor, comprising three lymphangiomas and one teratoma, evaluated by ultrasound and magnetic resonance imaging (MRI) between 26 and 37 weeks' gestation. The aim was to investigate the use of virtual bronchoscopy to evaluate fetal airway patency in each case. A three-dimensional (3D) model of the airway was created from overlapping image layers generated by MRI. The files obtained were manipulated using 3D modeling software, allowing the virtual positioning of observation cameras, adjustment of lighting parameters and creation of simulated 3D movies for analysis of a virtual path through the model. In all fetuses, fetal airway patency was clearly demonstrated by virtual bronchoscopy and this was confirmed postnatally. MRI with virtual bronchoscopy could become a useful tool for studying fetal airway patency in cases of cervical tumor.

Enzymatic synthesis of mono and dinucleoside polyphosphates

BACKGROUND

Mono and dinucleoside polyphosphates (p(n)Ns and Np(n)Ns) exist in living organisms and induce diverse biological effects through interaction with intracellular and cytoplasmic membrane proteins. The source of these compounds is associated with secondary activities of a diverse group of enzymes.

SCOPE OF REVIEW

Here we discuss the mechanisms that can promote their synthesis at a molecular level. Although all the enzymes described in this review are able to catalyse the in vitro synthesis of Np(n)Ns (and/or p(n)N), it is not clear which ones are responsible for their in vivo accumulation.

MAJOR CONCLUSIONS

Despite the large amount of knowledge already available, important questions remain to be answered and a more complete understanding of p(n)Ns and Np(n)Ns synthesis mechanisms is required. With the possible exception of (GTP:GTP guanylyltransferase of Artemia), all enzymes able to catalyse the synthesis of p(n)Ns and Np(n)Ns are unspecific and the factors that can promote their synthesis relative to the canonical enzyme activities are unclear.

GENERAL SIGNIFICANCE

The fact that p(n)Ns and Np(n)Ns syntheses are promiscuous activities of housekeeping enzymes does not reduce its physiological or pathological importance. Here we resume the current knowledge regarding their enzymatic synthesis and point the open questions on the field.

Additive manufacturing models of fetuses built from three-dimensional ultrasound, magnetic resonance imaging and computed tomography scan data

OBJECTIVE

To generate physical fetal models using images obtained by three-dimensional ultrasonography (3DUS), magnetic resonance imaging (MRI) and computed tomography (CT) to guide additive manufacturing technology.

METHODS

Images from 33 fetuses, including three sets of twins, were used. Fifteen fetuses were normal and evaluated only by 3DUS. Eighteen cases had abnormalities such as conjoined twins, tumors, aneuploidy, skeletal abnormalities, central nervous system abnormalities and facial or thoracic defects. Scans were performed using high-resolution 3DUS. In cases of abnormalities, MRI and CT were performed on the same day as 3DUS. The images obtained with 3DUS, CT or MRI were exported to a workstation in DICOM format. A single observer performed slice-by-slice manual segmentation using a digital high-definition screen. Software that converts medical images into numerical models was used to construct virtual 3D models, which were physically realized using additive manufacturing technologies.

RESULTS

Physical models based on 3DUS, MRI and CT images either separately or combined were successfully generated. They were remarkably similar to the postnatal appearance of the aborted fetus or newborn baby, especially in cases with pathology.

CONCLUSION

The use of 3DUS, MRI and CT may improve our understanding of fetal anatomical characteristics, and these technologies can be used for educational purposes and as a method for parents to visualize their unborn baby. The images can be segmented and applied separately or combined to construct 3D virtual and physical models.

Body fat in men with prolactinoma

OBJECTIVE

(a) To evaluate body fat in men with prolactinoma and healthy controls, using whole body dual energy x-ray absorptiometry (DXA), and (b) to correlate DXA results with anthropometry and clinical aspects of male prolactinomas.

MATERIAL AND METHODS

A cross-sectional study was performed in two University referral centers. Eleven newly-diagnosed men with prolactinoma and 9 with normal PRL levels due to dopamine agonist treatment were submitted to DXA and blood analysis (PRL, testosterone, dihydrotestosterone, estradiol, and SHBG) by the time of their clinical evaluation. They were compared with 14 control men of similar age and body mass index distribution.

RESULTS

Newly-diagnosed men with prolactinoma had higher fat percentage in the arms and the total body, when compared with patients treated with dopamine agonists and controls. The former group also presented higher fat percentage in the legs than the controls. Truncal fat percentage of the newly-diagnosed patients was lower than the dopamine agonist treated group. The 3 groups had similar android and gynoid fat contents. Fat percentage of the 6 sites correlated with PRL, testosterone, and dihydrotestosterone levels.

CONCLUSION

Newly-diagnosed men with prolactinomas had higher body fat content. Body fat was linked to disease control, especially to the PRL and androgen levels. Consequently, adequate control of hyperprolactinemia should be pursued in order to reduce the risk of obesity and its metabolic complications in men with prolactinoma.

Pyrophosphate and tripolyphosphate affect firefly luciferase luminescence because they act as substrates and not as allosteric effectors

The activating and stabilizing effects of inorganic pyrophosphate, tripolyphosphate and nucleoside triphosphates on firefly luciferase bioluminescence were studied. The results obtained show that those effects are a consequence of the luciferase-catalyzed splitting of dehydroluciferyl-adenylate, a powerful inhibitor formed as a side product in the course of the bioluminescence reaction. Inorganic pyrophosphate, tripolyphosphate, CTP and UTP antagonize the inhibitory effect of dehydroluciferyl-adenylate because they react with it giving rise to products that are, at least, less powerful inhibitors. Moreover, we demonstrate that the antagonizing effects depended on the rate of the splitting reactions being higher in the cases of inorganic pyrophosphate and tripolyphosphate and lower in the cases of CTP and UTP. In the case of inorganic pyrophosphate, the correlation between the rate of dehydroluciferyl-adenylate pyrophosphorolysis and the activating effect on bioluminescence only occurs for low concentrations because inorganic pyrophosphate is, simultaneously, an inhibitor of the bioluminescence reaction. Our results demonstrate that previous reports concerning the activating effects of several nucleotides (including some that do not react with dehydroluciferyl-adenylate) on bioluminescence were caused by the presence of inorganic pyrophosphate contamination in the preparations used.

Firefly luciferase produces hydrogen peroxide as a coproduct in dehydroluciferyl adenylate formation

Firefly luciferase catalyzes the synthesis of H2O2 from the same substrates as the bioluminescence reaction: ATP and luciferin (D-LH2). About 80% of the enzyme-bound intermediate D-luciferyl adenylate (D-LH2-AMP) is oxidized into oxyluciferin, and a photon is emitted during this reaction. The enzyme pathway responsible for the generation of H2O2 is a side reaction in which D-LH2-AMP is oxidized into dehydroluciferyl adenylate (L-AMP). Like the bioluminescence reaction, the luciferase-catalyzed synthesis of H2O2 and L-AMP is a stereospecific process, involving only the natural D enantiomer. However, the intramolecular electron transfer postulated as essential to the light emission process is not involved in this side reaction.

Coenzyme A affects firefly luciferase luminescence because it acts as a substrate and not as an allosteric effector

The effect of CoA on the characteristic light decay of the firefly luciferase catalysed bioluminescence reaction was studied. At least part of the light decay is due to the luciferase catalysed formation of dehydroluciferyl-adenylate (L-AMP), a by-product that results from oxidation of luciferyl-adenylate (LH2-AMP), and is a powerful inhibitor of the bioluminescence reaction (IC50 = 6 nm). We have shown that the CoA induced stabilization of light emission does not result from an allosteric effect but is due to the thiolytic reaction between CoA and L-AMP, which gives rise to dehydroluciferyl-CoA (L-CoA), a much less powerful inhibitor (IC50 = 5 microm). Moreover, the V(max) for L-CoA formation was determined as 160 min(-1), which is one order of magnitude higher than the V(max) of the bioluminescence reaction. Results obtained with CoA analogues also support the thiolytic reaction mechanism: CoA analogues without the thiol group (dethio-CoA and acetyl-CoA) do not react with L-AMP and do not antagonize its inhibitor effect; CoA and dephospho-CoA have free thiol groups, both react with L-AMP and both antagonize its effect. In the case of dephospho-CoA, it was shown that it reacts with L-AMP forming dehydroluciferyl-dephospho-CoA. Its slower reactivity towards L-AMP explains its lower potency as antagonist of the inhibitory effect of L-AMP on the light reaction. Moreover, our results support the conjecture that, in the bioluminescence reaction, the fraction of LH2-AMP that is oxidized into L-AMP, relative to other inhibitory products or intermediates, increases when the concentrations of the substrates ATP and luciferin increases.

Identification of luciferyl adenylate and luciferyl coenzyme a synthesized by firefly luciferase

The firefly luciferase reaction intermediate luciferyl adenylate was detected by RP-HPLC analysis when the luciferase reaction was performed under a nitrogen atmosphere. Although this compound is always specified as an intermediate in the light-production reaction, this is the first report of its identification by HPLC in a luciferase assay medium. Under a low-oxygen atmosphere, luciferase can catalyze the synthesis of luciferyl coenzyme A from luciferin, ATP, and coenzyme A, but in air dehydroluciferyl coenzyme A was produced. The luciferase-catalyzed synthesis of these coenzyme A derivatives may be a consequence of the postulated recent evolutionary origin of firefly luciferases from an ancestral acyl-coenzyme A synthetase.

pH opposite effects on synthesis of dinucleoside polyphosphates and on oxidation reactions catalyzed by firefly luciferase

Previous results have shown that an oxidizing product of firefly luciferin, dehydroluciferyl-adenylate, is the main intermediate in the process of synthesis of dinucleoside polyphosphates catalyzed by firefly luciferase (EC 1.13.12.7). However, we have found that the pH effects on the luciferase oxidizing processes and on the synthesis of dinucleoside polyphosphate are opposite: acidic assay media enhance the synthesis of dinucleoside polyphosphate and inhibit the oxidizing processes. The reason for this apparent contradiction lies on the activation effect of low pH on the adenylate transfer reaction from dehydroluciferyl-adenylate to the acceptor nucleotide.

An easy procedure to transform the ratio of two polynomials of first degree into Michaelis-Menten-type equations. Application to the ordered Uni Bi enzyme mechanism

It is not always clear that some equations affected by complicated factors can, actually, be interpreted as a ratio of two polynomials of first degree and so that they can be, in general, represented by rectangular hyperbolas. In this paper we present an easy procedure to rearrange those equations into Michaelis-Menten-type equations and so to make the aspects of these rectangular hyperbolas more clear, particularly for researchers familiar with general biochemistry. As an example, the method is applied to transform the classical rate equation of the Cleland's Ordered Uni Bi enzyme mechanism.

Inhibition and activation of enzymes. The effect of a modifier on the reaction rate and on kinetic parameters

A combined analysis of enzyme inhibition and activation is presented, based on a rapid equilibrium model assumption in which one molecule of enzyme binds one molecule of substrate (S) and/or one molecule of a modifier X. The modifier acts as activator (essential or non-essential), as inhibitor (total or partial), or has no effect on the reaction rate (v), depending on the values of the equilibrium constants, the rate constants of the limiting velocity steps, and the concentration of substrate ([S]). Different possibilities have been analyzed from an equation written to emphasize that v = f([X]) is, in general and at a fixed [S], a hyperbolic function. Formulas for Su (the value of [S], different from zero, at which v is unaffected by the modifier) and v(su) (v at that particular [S]) were deduced. In Lineweaver-Burk plots, the straight lines related to different [X] generally cross in a point (P) with coordinates (Su, v(su)). In certain cases, point P is located in the first quadrant which implies that X acts as activator, as inhibitor, or has no effect, depending on [S]. Furthermore, we discuss: (1) the apparent Vmax and Km displayed by the enzyme in different situations; (2) the degree of effect (inhibition or activation) observed at different concentrations of substrate and modifier; (3) the concept of Ke, a parameter that depends on the concentration of substrate and helps to evaluate the effect of the modifier: it equals the value of [X] at which the increase or decrease in the reaction rate is half of that achieved at saturating [X]. Equations were deduced for the general case and for particular situations, and used to obtain computer-drawn graphs that are presented and discussed. Formulas for apparent Vmax, Km and Ke have been written in a way making it evident that these parameters can be expressed as pondered means.

Angiographic evaluation of graft patency in minimally invasive direct coronary artery bypass grafting

BACKGROUND

The objective of this report is to describe our experience using minimally invasive direct coronary artery bypass grafting and to evaluate angiographic patency of anastomoses.

METHODS

A total of 120 patients (86 men) were operated on, with ages ranging from 30 to 83 years (mean = 61.2 years). Two access routes were used: for single left anterior descending coronary artery lesions an 8 cm anterior minithoracotomy was performed at the fourth left intercostal space. Extracorporeal circulation was not used. In the last 82 patients a restraining device was used for the regional reduction of heart beats. Coronary cineangiography was carried out between postoperative days 1 and 3 in 84 (70%) patients. Anastomoses were graded: grade A, no blocks; grade B, blocks of more than 50%; grade C, occlusion. This evaluation was performed for two different periods: in the first period a restraining device was not used and in the second period a restraining device was used.

RESULTS

In the first study period (38 anastomoses) coronary cineangiography showed grade A, 79%, grade B, 5.2%, and grade C, 15.8%. In the second study period (62 anastomoses), angiography showed grade A, 90.4%, grade B, 6.4%, and grade C, 3.2%. Early mortality was 1.6%.

CONCLUSIONS

Minimally invasive coronary artery bypass grafting is a good alternative for some groups of patients. Anastomotic results seem to be better when a restraining device is used.

An easy procedure to transform the ratio of two polynomials of first degree into Michaelis-Menten-type equations. Application to the ordered Uni Bi enzyme mechanism

It is not always clear that some equations affected by complicated factors can, actually, be interpreted as a ratio of two polynomials of first degree and so that they can be, in general, represented by rectangular hyperbolas. In this paper we present an easy procedure to rearrange those equations into Michaelis-Menten-type equations and so to make the aspects of these rectangular hyperbolas more clear, particularly for researchers familiar with general biochemistry. As an example, the method is applied to transform the classical rate equation of the Cleland's Ordered Uni Bi enzyme mechanism.

Inhibition and activation of enzymes. The effect of a modifier on the reaction rate and on kinetic parameters

A combined analysis of enzyme inhibition and activation is presented, based on a rapid equilibrium model assumption in which one molecule of enzyme binds one molecule of substrate (S) and/or one molecule of a modifier X. The modifier acts as activator (essential or non-essential), as inhibitor (total or partial), or has no effect on the reaction rate (v), depending on the values of the equilibrium constants, the rate constants of the limiting velocity steps, and the concentration of substrate ([S]). Different possibilities have been analyzed from an equation written to emphasize that v = f([X]) is, in general and at a fixed [S], a hyperbolic function. Formulas for Su (the value of [S], different from zero, at which v is unaffected by the modifier) and v(su) (v at that particular [S]) were deduced. In Lineweaver-Burk plots, the straight lines related to different [X] generally cross in a point (P) with coordinates (Su, v(su)). In certain cases, point P is located in the first quadrant which implies that X acts as activator, as inhibitor, or has no effect, depending on [S]. Furthermore, we discuss: (1) the apparent Vmax and Km displayed by the enzyme in different situations; (2) the degree of effect (inhibition or activation) observed at different concentrations of substrate and modifier; (3) the concept of Ke, a parameter that depends on the concentration of substrate and helps to evaluate the effect of the modifier: it equals the value of [X] at which the increase or decrease in the reaction rate is half of that achieved at saturating [X]. Equations were deduced for the general case and for particular situations, and used to obtain computer-drawn graphs that are presented and discussed. Formulas for apparent Vmax, Km and Ke have been written in a way making it evident that these parameters can be expressed as pondered means.

Acyl-CoA synthetase catalyzes the synthesis of diadenosine hexaphosphate (Ap6A)

The synthesis of diadenosine hexaphosphate (Ap6A), a potent vasoconstrictor, is catalyzed by acyl-CoA synthetase from Pseudomonas fragi. In a first step AMP is transferred from ATP to tetrapolyphosphate (P4) originating adenosine pentaphosphate (p5A) which, subsequently, is the acceptor of another AMP moiety from ATP generating diadenosine hexaphosphate (Ap6A). Diadenosine pentaphosphate (Ap5A) and diadenosine tetraphosphate (Ap4A) were also synthesized in the course of the reaction. In view of the variety of biological effects described for these compounds the potential capacity of synthesis of diadenosine polyphosphates by the mammalian acyl-CoA synthetases may be relevant.

Dehydroluciferyl-AMP is the main intermediate in the luciferin dependent synthesis of Ap4A catalyzed by firefly luciferase

It was previously assumed that E x LH2-AMP was the intermediate complex in the synthesis of Ap4A catalyzed by firefly luciferase (EC 1.13.12.7), when luciferin (LH2) was used as cofactor. However, here we show that LH2 is partly transformed, shortly after the onset of the luciferase reaction, to dehydroluciferin (L) with formation of an E x L-AMP complex which is the main intermediate for the synthesis of Ap4A. Formation of three more derivatives of LH2 were also observed, related to the production of light by the enzyme. CoA, a known stimulator of light production, inhibits the synthesis of Ap4A by reacting with the E x L-AMP complex and yielding L-CoA.

Acyl coenzyme A synthetase from Pseudomonas fragi catalyzes the synthesis of adenosine 5'-polyphosphates and dinucleoside polyphosphates

Acyl coenzyme A (CoA) synthetase (EC 6.2.1.8) from Pseudomonas fragi catalyzes the synthesis of adenosine 5'-tetraphosphate (p4A) and adenosine 5'-pentaphosphate (p5A) from ATP and tri- or tetrapolyphosphate, respectively. dATP, adenosine-5'-O-[gamma-thiotriphosphate] (ATP gamma S), adenosine(5')tetraphospho(5')adenosine (Ap4A), and adenosine(5')pentaphospho(5')adenosine (Ap5A) are also substrates of the reaction yielding p4(d)A in the presence of tripolyphosphate (P3). UTP, CTP, and AMP are not substrates of the reaction. The K(m) values for ATP and P3 are 0.015 and 1.3 mM, respectively. Maximum velocity was obtained in the presence of MgCl2 or CoCl2 equimolecular with the sum of ATP and P3. The relative rates of synthesis of p4A with divalent cations were Mg = Co > Mn = Zn >> Ca. In the pH range used, maximum and minimum activities were measured at pH values of 5.5 and 8.2, respectively; the opposite was observed for the synthesis of palmitoyl-CoA, with maximum activity in the alkaline range. The relative rates of synthesis of palmitoyl-CoA and p4A are around 10 (at pH 5.5) and around 200 (at pH 8.2). The synthesis of p4A is inhibited by CoA, and the inhibitory effect of CoA can be counteracted by fatty acids. To a lesser extent, the enzyme catalyzes the synthesis also of Ap4A (from ATP), Ap5A (from p4A), and adenosine(5')tetraphospho(5')nucleoside (Ap4N) from adequate adenylyl donors (ATP, ATP gamma S, or octanoyl-AMP) and adequate adenylyl acceptors (nucleoside triphosphates).

Synthesis of dehydroluciferin by firefly luciferase: effect of dehydroluciferin, coenzyme A and nucleoside triphosphates on the luminescent reaction

The formation of dehydroluciferin (L) from luciferin (LH2) in the reaction catalyzed by firefly luciferase (EC 1.13.12.7) has been studied. The E.LH2-AMP complex may follow two different pathways: towards production of light and towards the synthesis of the E.L-AMP complex. This last step has an inhibitory effect on light emission as molecules of the enzyme are trapped in a light unproductive complex. The effects of CoA and nucleoside 5'-triphosphates (NTPs) on light emission are quantitatively different. CoA combines with the L moiety of the E.L-AMP complex, yielding L-CoA, promoting liberation of free luciferase, and increasing light yield. NTP reacts with the AMP moiety of the same complex, generating adenosine(5')tetraphospho(5')nucleoside (Ap4N) and, probably, the E. L complex and scarcely increasing light production. The results are discussed in relation to previous reports, by others, on luciferase.

Enzyme inhibition as visualized with the reservoir model: relationships between I50 and inhibition constant(s) of an enzyme inhibitor

In the reservoir model, enzyme activity is simulated by holes in the wall of a reservoir (metabolic pool) containing liquid (substrate) at a certain level (concentration). The holes are computer drawn to reflect the kinetic properties of the enzyme, namely its maximum velocity (hole area) and Km (hole position). The model is here presented as a tool to intuitively visualize the effect of the different types of reversible enzyme inhibitors on the kinetic properties of an enzyme. The relationships between the concentration of an inhibitor producing 50% inhibition of an enzyme reaction (I50) and its inhibition constant(s) are also discussed.

A tridimensional representation of enzyme inhibition useful for diagnostic purposes

A new three dimensional representation of enzyme inhibition, applied to Lineweaver-Burk, Hanes and Eadie-Hofstee plots is presented. This type of representation has advantages for enzyme inhibition diagnosis, showing graphic characteristics that pass unnoticed in linear plots.

Extensive deposition of basement membrane by tumours: a prognostic factor? A reappraisal

A loss of the continuous linear deposit of basement membrane around invasive carcinomas has been suggested to correlate with their increased invasiveness. In contrast, extensive basement membrane deposition would represent a more favourable prognosis. The Engelbreth-Holm-Swarm (EHS) tumour, a transplantable neoplasm, is widely used for its ability to synthesize and deposit large amounts of basement membrane components. We have evaluated the metastatic potential of this neoplasm 2 months after subcutaneous inoculation. Histological examination of lung sections revealed the presence of numerous metastatic foci. The metastatic cells retained their organization into clusters surrounded by extracellular matrix. Both the 72 kDa and the 92 kDa type IV collagenases were detected by zymography in Triton or urea extract (matrigel) of primary tumour. These results cast doubt on the hypothesis that the extensiveness of basement membrane deposition might always be of prognostic value by being inversely correlated with the degree of invasiveness of a carcinoma.