Associations between Host Genetic Variants and Subgingival Microbiota in Patients with the Metabolic Syndrome

Host genetic variants may affect oral biofilms, playing a role in the periodontitis-systemic disease axis. This is the first study to assess the associations between host genetic variants and subgingival microbiota in patients with metabolic syndrome (MetS); 103 patients with MetS underwent medical and periodontal examinations and had blood and subgingival plaque samples taken. DNA was extracted and processed, assessing a panel of selected single nucleotide polymorphisms (SNPs) first (hypothesis testing) and then expanding to a discovery phase. The subgingival plaque microbiome from these patients was profiled. Analysis of associations between host genetic and microbial factors was performed and stratified for periodontal diagnosis. Specific SNPs within RUNX2, CAMTA1 and VDR genes were associated with diversity metrics with no genome-wide associations detected for periodontitis severity or Mets components at p < 10-7. Severe periodontitis was associated with pathogenic genera and species. Some SNPs correlated with specific bacterial genera as well as with microbial taxa, notably VDR (rs12717991) with Streptococcus mutans and RUNX2 (rs3749863) with Porphyromonas gingivalis. In conclusion, variation in host genotypes may play a role in the dysregulated immune responses characterizing periodontitis and thus the oral microbiome, suggesting that systemic health-associated host traits further interact with oral health and the microbiome.

The multifaceted spectrum of liver cirrhosis in older hospitalised patients: analysis of the REPOSI registry

BACKGROUND

Knowledge on the main clinical and prognostic characteristics of older multimorbid subjects with liver cirrhosis (LC) admitted to acute medical wards is scarce.

OBJECTIVES

To estimate the prevalence of LC among older patients admitted to acute medical wards and to assess the main clinical characteristics of LC along with its association with major clinical outcomes and to explore the possibility that well-distinguished phenotypic profiles of LC have classificatory and prognostic properties.

METHODS

A cohort of 6,193 older subjects hospitalised between 2010 and 2018 and included in the REPOSI registry was analysed.

RESULTS

LC was diagnosed in 315 patients (5%). LC was associated with rehospitalisation (age-sex adjusted hazard ratio, [aHR] 1.44; 95% CI, 1.10-1.88) and with mortality after discharge, independently of all confounders (multiple aHR, 2.1; 95% CI, 1.37-3.22), but not with in-hospital mortality and incident disability. Three main clinical phenotypes of LC patients were recognised: relatively fit subjects (FIT, N = 150), subjects characterised by poor social support (PSS, N = 89) and, finally, subjects with disability and multimorbidity (D&M, N = 76). PSS subjects had an increased incident disability (35% vs 13%, P < 0.05) compared to FIT. D&M patients had a higher mortality (in-hospital: 12% vs 3%/1%, P < 0.01; post-discharge: 41% vs 12%/15%, P < 0.01) and less rehospitalisation (10% vs 32%/34%, P < 0.01) compared to PSS and FIT.

CONCLUSIONS

LC has a relatively low prevalence in older hospitalised subjects but, when present, accounts for worse post-discharge outcomes. Phenotypic analysis unravelled the heterogeneity of LC older population and the association of selected phenotypes with different clinical and prognostic features.

Inflammation and ventricular-vascular coupling in hypertensive patients with metabolic syndrome

BACKGROUND AND AIMS

Metabolic syndrome (MetS) is currently considered to raise the risk for type 2 diabetes and cardiovascular events. It has been suggested that part of this risk excess may be due to a cluster of additional factors associated with MetS. We aimed to investigate the role of inflammation on the ventricular-vascular coupling in patients with MetS.

METHODS AND RESULTS

We enrolled a total of 227 hypertensive patients (106 with MetS and 121 without MetS) matched for age and gender. Aortic pulse wave velocity (aPWV), intima-media thickness (IMT) and high sensitivity C-reactive protein (CRP) increased according to the number of MetS components. Patients with MetS showed increased aPWV (11.5 ± 3.7 vs. 10.3 ± 2.5 m/s, P = 0.03) compared with controls. In a model adjusted for age, sex, heart rate and mean blood pressure, aPWV resulted increased in patients with CKD (beta 1.29 m/s, 95%CI 0.61-1.96 m/s, P < 0.001) and MetS (beta 0.89 m/s, 95%CI 0.28-1.51 m/s, P = 0.005). After additional adjustment for CRP and IMT, the slope of aPWV was respectively reduced by 16% and 62%, suggesting that inflammation and intima-media thickening could contribute to aortic stiffening in patients with MetS. In these patients, aPWV was also associated with left-ventricular mass index (beta 0.79 g/m^2.7, 95%CI 0.05-1.52 g/m^2.7, P = 0.05).

CONCLUSION

MetS is characterized by an inflammation-dependent acceleration in cardiovascular ageing. This pattern of pathophysiological abnormalities may contribute to amplify the burden of cardiovascular risk in patients with MetS.

Microcirculatory changes in children undergoing cardiac surgery: a prospective observational study

BACKGROUND

The effects of cardiac surgery on the microcirculation of children are unknown. The aim of this study was to assess the microcirculatory changes in children undergoing surgery for correction of congenital heart disease.

METHODS

We used a videomicroscope (Sidestream Dark Field, SDF) in a convenience sample of 24 children <five yr old. Total vascular density (TVD, vessels mm(-2)), microvascular flow index (MFI, arbitrary units), proportion of perfused small vessels (PPV, percentage), and perfused vessel density (PVD) were obtained after induction of anaesthesia (T1), at the end of the surgical procedure (T2), after intensive care unit (ICU) admission (T3), and at six h (T4) and 12h (T5) after ICU admission.

RESULTS

Microcirculatory variables did not significantly change over time. Haemodynamic parameters and microcirculatory variables were not correlated. In a subanalysis conducted for cyanotic (n=7) and acyanotic (n=17) children, repeated measures ANOVA showed a significant interaction between time and the presence of cyanosis for PPV (P=0.03), TVD (P=0.03), and PVD (P=0.03). Weak inverse correlations were found between storage time of transfused red blood cell (RBCs) and MFI at T3 (r=-0.63, P=0.01) and T4 (r=-0.53, P=0.03).

CONCLUSIONS

Microcirculatory variables have a different time-related trend in cyanotic and acyanotic children undergoing cardiac surgery. The storage time of transfused RBCs seems to negatively impact the microcirculation. Further and larger studies are warranted to prove the potential implications of this study.

B-type natriuretic peptide may predict prognosis in older adults admitted with a diagnosis other than heart failure

BACKGROUND AND AIMS

The diagnosis of heart failure (HF) in elderly patients is often difficult, due to overlap of typical signs and symptoms with those of comorbidities. B-type Natriuretic Peptide (BNP) predicts diagnosis and prognosis of HF, but little is known on its predictive role of short-term prognosis when admission diagnosis is other than HF.

METHODS AND RESULTS

We prospectively recruited 404 consecutive patients (aged≥65 years) hospitalized in the Unit of Internal Medicine, University of Catania, Catania, Italy, with an admission diagnosis other than HF. Clinical examination, laboratory data and BNP were evaluated at the admission. The predictive value of BNP and other variables for in-hospital mortality, thirty-day mortality and three month re-hospitalization was assessed. During hospitalization 48 (12%) patients died; by logistic regression analysis, in-hospital mortality was not predicted by BNP>600 pg/ml (OR = 1.36; CI 95% = 0.60-2.80; p = 0.4), while it was by chronic kidney disease (CKD, p < 0.001), WBC count (p < 0.001), immobilization syndrome (p < 0.008) and age (p = 0.012). After discharge, 54 patients (15%) died within 30 days; in these patients thirty-day mortality was significantly predicted by BNP>600 pg/ml (OR = 2.70; CI 95% = 1.40-5.00; p = 0.001), CKD (p < 0.001), malnutrition (p = 0.029) and age (p = 0.033). Re-hospitalized patients were 97 (32%); three month re-hospitalization was predicted by BNP>600 pg/ml (OR = 12.28; CI 95% = 6.00-24.90; p < 0.001) and anamnestic HF (p = 0.002).

CONCLUSIONS

Our study shows that BNP>600 pg/ml, CKD, malnutrition and age predict thirty-day mortality after discharge in elderly patients with an admission diagnosis other than HF, while CKD, WBC count, immobilization syndrome and age predict in-hospital mortality. Three-month re-hospitalization was predicted by BNP>600 pg/ml and anamnestic HF.

Neutrophil-To-Lymphocyte Ratio: An Emerging Marker Predicting Prognosis in Elderly Adults with Community-Acquired Pneumonia

OBJECTIVES

To explore the performance of the neutrophil-to-lymphocyte ratio (NLR), an index of systemic inflammation that predicts prognosis of several diseases, in a cohort of elderly adults with community-acquired pneumonia (CAP).

DESIGN

Prospective clinical study from January 2014 to July 2016.

SETTING

Unit of Internal Medicine, University of Catania, Catania, Italy.

PARTICIPANTS

Elderly adults admitted for CAP (N = 195).

MEASUREMENTS

Clinical diagnosis of CAP was defined as the presence of a new infiltrate on plain chest radiography or chest computed tomography associated with one or more suggestive clinical features such as dyspnea, hypo- or hyperthermia, cough, sputum production, tachypnea (respiration rate >20 breaths per minute), altered breath sounds on physical examination, hypoxemia (partial pressure of oxygen <60 mmHg), leukocytosis (white blood cell count >10,000/μL). Clinical examination, traditional tests such as Pneumonia Severity Index (PSI); Confusion, Urea, Respiratory rate, Blood pressure, aged 65 and older (CURB-65), and NLR were evaluated at admission. The accuracy and predictive value for 30-day mortality of traditional scores and NLR were compared.

RESULTS

NLR predicted 30-day mortality (P < .001) and performed better than PSI (P < .05), CURB-65, C-reactive protein, and white blood cell count (P < .001) to predict prognosis. No deaths occurred in participants with a NLR of less than 11.12. Thirty-day mortality was 30% in those with a NLR between 11.12% and 13.4% and 50% in those with a NLR between 13.4 and 28.3. All participants with a NLR greater than 28.3 died within 30 days.

CONCLUSIONS

These results would encourage early discharge of individuals with a NLR of less than 11.12, short-term in-hospital care for those with a NLR between 11.12 and 13.4, middle-term hospitalization for those with a NLR between 13.4 and 28.3, and admission to a respiratory intensive care unit for those with a NLR greater than 28.3.

Mean Transaortic Gradient is an Emerging Predictor of Chronic Kidney Disease in Elderly Patients

Arterial hypertension (AH) is a major risk factor for chronic kidney disease (CKD). However, whether AH maintains this role in the development of CKD in elderly patients with aortic stenosis (AS) or whether transaortic gradient influences CKD remains unclear. Consecutive hospitalized patients were prospectively recruited to evaluate the relationship between AS and CKD. In all patients, transthoracic 2-dimensional echocardiography was performed to evaluate AS; renal function was evaluated using the Chronic Kidney Disease Epidemiology Collaboration formula. A total of 346 patients were included in the study (mean age: 79.5 ± 7.4 years): 104 had diabetes mellitus (DM), 298 had AH, and 59 (moderate: 52; severe: 7) showed AS. After multivariate analysis, age ( P <.01), DM ( P = .02), and mean transaortic gradient ( P = .03), but not AH, were independent predictors of CKD. Both in the presence (n = 59) or absence (n = 287) of AS, the estimated glomerular filtration rate did not differ in patients with (51 ± 24 mL/min/1.73 m2 and 59 ± 25 mL/min/1.73 m2, respectively) and those without AH (50 ± 21 mL/min/1.73 m2 and 65 ± 24 mL/min/1.73 m2, respectively). In the whole population, for each mm Hg of mean transaortic gradient, the risk of CKD increased by 2.5 times.

Impact of left ventricular remodeling and renal function on 24h-ECG recordings and cardiovascular outcome in elderly hypertensive patients

BACKGROUND

The prognostic role of left ventricular remodeling and renal function in elderly hypertensive patients has been so far scarcely investigated.

AIMS

We assessed the impact of left ventricular geometry and renal function on 24h-Holter electrocardiogram (ECG) recordings and outcome in elderly hypertensive patients.

METHODS

We enrolled 251 asymptomatic hypertensive elderly patients (>65year-old). Left ventricular remodeling was evaluated by 2-D echocardiogram. Lown's class, mean QTc and standard deviation of all normal R-R intervals (SDNN) were assessed by 24-h Holter-ECG recordings. Data on all-cause and cardiovascular mortality were collected for 2years.

RESULTS

Mean age was 76.2±11.4years. High Lown's classes were more frequently observed in the presence of left ventricular hypertrophy (LVH) (57.3% vs. 23.7%; p<0.001). Mean QTc was 444.8±34.8ms and resulted directly correlated with indexed left ventricular mass (r=0.228; p=0.001). Patients with Chronic Kidney Disease (CKD) showed lower SDNN as compared with those with preserved renal function (92.02±36.11ms vs. 103.84±33.96ms, respectively; p=0.017). At 2years, all-cause and cardiovascular mortality rates were 38.0% and 21.1%, respectively. Diabetes mellitus (HR: 2.40; 95% C.I.1.16 to 4.99; p=0.019), CKD (HR: 2.22; 95% C.I.1.10 to 4.52; p=0.028), prolonged QTc (HR: 2.18; 95% C.I.1.07 to 4.41; p=0.030) and SDNN<96ms (HR: 1.98; 95% C.I.1.03 to 4.13; p=0.048) were independent predictors of cardiovascular death at 2year follow-up.

CONCLUSIONS

CKD and left ventricular remodeling predicted altered ventricular batmotropism. Diabetes, CKD, heart rate variability and QTc are important predictors of cardiovascular death in elderly hypertensive patients.

Comparison of Wells and Revised Geneva Rule to Assess Pretest Probability of Pulmonary Embolism in High-Risk Hospitalized Elderly Adults

OBJECTIVES

To assess and compare the diagnostic power for pulmonary embolism (PE) of Wells and revised Geneva scores in two independent cohorts (training and validation groups) of elderly adults hospitalized in a non-emergency department.

DESIGN

Prospective clinical study, January 2011 to January 2013.

SETTING

Unit of Internal Medicine inpatients, University of Catania, Italy.

PARTICIPANTS

Elderly adults (mean age 76 ± 12), presenting with dyspnea or chest pain and with high clinical probability of PE or D-dimer values greater than 500 ng/mL (N = 203), were enrolled and consecutively assigned to a training (n = 101) or a validation (n = 102) group. The clinical probability of PE was assessed using Wells and revised Geneva scores.

MEASUREMENTS

Clinical examination, D-dimer test, and multidetector computed angiotomography were performed in all participants. The accuracy of the scores was assessed using receiver operating characteristic analyses.

RESULTS

PE was confirmed in 46 participants (23%) (24 training group, 22 validation group). In the training group, the area under the receiver operating characteristic curve was 0.91 (95% confidence interval (CI) = 0.85-0.98) for the Wells score and 0.69 (95% CI = 0.56-0.82) for the revised Geneva score (P < .001). These results were confirmed in the validation group (P < .05). The positive (LR+) and negative likelihood ratios (LR-) (two indices combining sensitivity and specificity) of the Wells score were superior to those of the revised Geneva score in the training (LR+, 7.90 vs 1.34; LR-, 0.23 vs 0.66) and validation (LR+, 13.5 vs 1.46; LR-, 0.47 vs 0.54) groups.

CONCLUSION

In high-risk elderly hospitalized adults, the Wells score is more accurate than the revised Geneva score for diagnosing PE.

Testing Clinical Scores to Diagnose Incident Deep Vein Thrombosis in Patients Hospitalized in a Department of Medicine: Can Biomarkers Improve Accuracy?

Shifting the context from the emergency department to the department of medicine, we compared different scores to diagnose deep vein thrombosis (DVT) in patients with several comorbidities, hospitalized in a department of internal medicine. We prospectively recruited 178 consecutive hospitalized patients in whom clinical suspicion of DVT was assessed by Wells modified score for DVT, Hamilton, Kahn, and St Andrè Hospital scores. Deep vein thrombosis was confirmed in 85 (48%) patients by both echocolor Doppler and angiocomputed tomography scan. The use of risk scores based on symptoms and clinical signs was weakly useful (area under the curve [AUC]: 0.69, positive predictive value: 59%, and negative predictive value: 74%). Patients with DVT had significantly (P < .0001) lower serum albumin and protein S levels compared to those without DVT. Moreover, serum protein S (AUC: 0.82) and albumin in percentage (AUC: 0.80) showed a better accuracy than clinical scores (P < .001) in assessing the diagnosis of DVT. Therefore, serum albumin and protein S improved the accuracy of clinical scores for the diagnosis of incident DVT in patients hospitalized in a department of medicine.

Glucose-mediated alteration of cellular function in human periodontal ligament cells

Because diabetic patients are easily led to manifest severe periodontitis, we wanted to determine whether various glucose levels interfere with normal cellular function. Human periodontal ligament (PDL) cells were cultured in glucose-free medium, or in medium containing either 1100 mg/L of glucose (normal-glucose medium) or 4500 mg/L of glucose (high-glucose medium). Cells cultured in glucose-free medium changed their morphology from spindle-shaped to round, and incorporated trypan blue in a time-dependent manner. The incorporation rate was much faster in cells with shorter cell cycles than in those with longer cycles, suggesting the involvement of cell-cycle progression in cell death. However, fragmented DNA, which suggests apoptotic cell death, was not observed in these cells. We reasoned that initial cell rounding and detachment from the culture plate might be due to the conformational changes in cell-surface receptors to fibronectin, a major extracellular matrix for fibroblasts. Western blot analysis revealed that cells cultured in glucose-free medium lost their fibronectin receptor in a time-dependent manner. In addition, fibronectin receptor expression was much higher in cells cultured in high-glucose medium than in cells cultured in normal-glucose medium. Furthermore, the over-expression of the fibronectin receptor resulted in a suppressed chemotactic response of these cells to platelet-derived growth factor. On the basis of these data, it was hypothesized that a high glucose level induced over-expression of these receptors. This might be the mechanism by which a high glucose level compromises wound healing in diabetic patients and, at least in part, might be the reason diabetic patients are subject to severe periodontal destruction.

Perinatal food restriction in rats reduces the content but not concentration of liver extracellular matrix proteins

Fibrosis of the liver has been reported to be associated with malnutrition, based on qualitative histological and histochemical approaches. The aim of this study was to quantitatively examine the effect of perinatal food-restriction on the expression of extracellular matrix components of the liver, using rats fed 50% of ad libitum intake, determined by the food consumption of the control group on the previous day. Levels of extracellular matrix proteins were measured by dot blot analysis using monospecific antibodies against collagen types I, III and IV, laminin and fibronectin. The body weights of 4, 8 and 13-wk-old malnourished groups were 25, 35 and 48% of the control group body weights, respectively, and the liver weights were 22, 32 and 60% of the controls. The total contents of the extracellular matrix components were significantly reduced to 30, 34 and 58% of the controls, but when expressed per tissue or per milligram protein there were no significant differences. Indirect immunofluorescence revealed no major changes in extracellular matrix localization. The major histological change in the food-restricted rats was fatty infiltration. Our observations suggest that the effect of perinatal food restriction is mainly liver steatosis, and that the liver of food-restricted animals during the perinatal period has the capacity to preserve its main extracellular matrix components.

Glomerular lesions induced in the rabbit by physicochemically altered homologous IgG

Immunization of rabbits with physicochemically altered homologous or even autologous IgG induces formation of antibodies combining with IgG of rabbit and of foreign species. Cardiac but not renal lesions were reported in such animals. This study examined the nephritogenic potential of the immune response to cationized or heat-aggregated homologous IgG of b9 or b4 allotype in rabbits of the b4 allotype. Rabbits injected with either b9 or b4 cationized IgG produced antibodies reactive with rabbit and human IgG and with histones; they also developed abnormal glomerular deposits of IgG b4 and C3 corresponding to alterations of the glomerular basement membranes (GBM). Rabbits injected with either b9 or b4 aggregated IgG developed antibodies reactive with rabbit and human IgG and abnormal glomerular deposits of IgG b4 and C3 in the GBM and in the mesangium with subendothelial and mesangial electron-dense deposits. Some rabbits in both groups had proliferative and exudative glomerulonephritis and proteinuria. The results showed that immunization of rabbits with physicochemically altered homologous IgG induces an immune response to rabbit and human IgG and to histones as well as glomerular deposits of autologous IgG and C3 and other glomerular lesions.

Advances in diagnosis and detection of oral diseases

Medicine, particularly with respect to diagnostic decision-making, has seen remarkable advances in the last ten years. The art of diagnosis has become much more of a science. Basic science advances have moved from the laboratory into the hospital and radically changed the way a medical diagnosis is arrived at or confirmed. Dentistry, especially oral diagnosis, as yet has not been a significant part of this general medical advance. However, several examples demonstrate that this situation is starting to change. Oral conditions are beginning to be evaluated with greater precision and sophistication. This report reviews some recent advances in oral diagnostic research and suggests where they will carry dentistry over the next 25 years.

Neuropeptides are chemoattractants for human tumor cells and monocytes: a possible mechanism for metastasis

Bombesin (BN), a tetradecapeptide neuropeptide growth factor, is shown to be a potent (ED50 of 5 X 10(-12) M) chemoattractant for human monocytes and small cell lung carcinoma cells (SCCL). These effects are BN receptor-mediated since potencies of several BN analogs to induce chemotaxis and to inhibit [125I-tyr4] BN binding activity correlate well (P less than 0.001). As has been demonstrated for other BN receptor-mediated effects, carboxy-terminal amino acids are required for optimum biological activity. BN is not an exclusive chemoattractant for SCCL cells but was also active in promoting migration of other, but not all, lung tumor cells. Other neuropeptides, such as beta-endorphin, substance P, and arg-vasopressin, are also shown to be chemoattractants for SCCL cells, with EC50's also in the 10(-12) M range. The ability of these ligands to effect monocyte and some tumor cell migration suggest a role for neuropeptides in inflammation and metastasis. In the latter case, tumor cells, in response to neuropeptide chemical gradients, may become localized at specific body sites. Neuropeptide release, in response to cognitive or other stimuli, may thereby modify cell migratory patterns. Additionally, such hormones may influence early developmental events such as tissue organization and histogenesis.

Stimulation of retinoic acid of synthesis and turnover of basement membrane in mouse embryonal carcinoma-derived endoderm cells

The effect of retinoic acid on the synthesis and degradation of basement membrane components by endoderm cells derived from mouse embryonal carcinoma (EC) cells was studied in a serum-free, defined medium. By immunofluorescence these cells accumulate type IV collagen, laminin, and fibronectin after growth in media containing epidermal growth factor (EGF), fibroblast growth factor (FGF), insulin, transferrin, and Pedersen fetuin. Collagen accounted for 2 to 4% of the newly synthesized proteins, of which 90% were found in the culture media. This collagen was identified as Pro-type IV be gel electrophoresis and enzymatic susceptibility. The EC cells preferentially attached to type IV collagen in vitro and such attachment was mediated by laminin. Treatment of EC cells with retinoic acid caused an increased accumulation of collagen (10 to 15% of secreted proteins) and also stimulated the elaboration of latent protease which degraded laminin and type IV collagen. The laminin-degrading activity was plasminogen dependent. The type IV collagen-degrading activity was a metal protease which could be activated by trypsin or plasmin. It is likely that at least part of the laminin degrading activity is plasmin (mediated through plasminogen activator), since highly purified plasmin is shown to degrade native laminin.

Effect of plasminogen activator (urokinase), plasmin, and thrombin on glycoprotein and collagenous components of basement membrane

Tumor cells traverse basement membranes (BM) during the stages of the metastatic process. Penetration of the BM may involve proteolysis by enzymes directly or indirectly associated with tumor cells. This study evaluated the role of the serine proteases urokinase (plasminogen activator), plasmin, and another regulatory protease, alpha-thrombin, in the degradation of the BM. Homogeneously pure enzyme preparations were incubated with isolated components of BM and with whole human amnion BM. The BM components consisted of acid-extracted type IV collagen, pepsin fragments of collagen type IV, laminin, and fibronectin. Collagen type V (alpha A alpha B) associated with the peri-BM zone was also studied. The purity of the enzymes was verified by gel electrophoresis and inhibitor studies. Digestion of the BM components was performed at 25 degrees using matched activity for the different enzymes. Urokinase failed to significantly degrade fibronectin or any of the other BM components. Under the same 25 degrees (native) conditions, plasmin and thrombin cleaved fibronectin and laminin into multiple specific fragments but did not produce a major cleavage of acid-extracted type IV collagen, pepsinized type IV collagen, or alpha A alpha B (type V) collagade fibronectin or any of the other BM components. Under the same 25 degrees (native) conditions, plasmin and thrombin cleaved fibronectin and laminin into multiple specific fragments but did not produce a major cleavage of acid-extracted type IV collagen, pepsinized type IV collagen, or alpha A alpha B (type V) collagade fibronectin or any of the other BM components. Under the same 25 degrees (native) conditions, plasmin and thrombin cleaved fibronectin and laminin into multiple specific fragments but did not produce a major cleavage of acid-extracted type IV collagen, pepsinized type IV collagen, or alpha A alpha B (type V) collagen. alpha-Thrombn selectively degraded only the m.w. 400,000 chain of laminin, whereas plasmin degraded both the laminin chains. Digestion of laminin by the serine proteases was time and concentration dependent, as verified by a new degradation assay using [14C]laminin. A variety of normal and neoplastic cells were tested for the presence of laminin-degrading proteases. macrophages, polymorphonuclear leukocytes, and metastatic tumor cells contained a significant laminin-degarding activity. The activity was enhanced by the addition of plasminogen. Type V collagen was cleaved by thrombin and plasmin at 35 degrees but not at temperatures below 33 degrees. Following treatment of whole-amnion BM with any of these enzymes, electron microscopy demonstrated preservation of the lamina densa. Immunohistology studies indicated that laminin, but not type IV collagen, was removed from the whole BM by plasmin treatment. The results suggest that these BM components are poor substrates for plasminogen activators and that plasmin alone is not sufficient to completely degrade the whole BM...

The effects of laminin on the growth and differentiation of embryonal carcinoma cells in defined media

In this paper we have examined the growth and differentiation of the embryonal carcinoma cell line, F9, in the defined medium EM-3 at low density. We show that the growth of F9 and their differentiated cells (F9-diff) in EM-3 is strongly density dependent. At low cell densities the growth of both cell types is severely limited and most of the cells do not survive. Although this poses a problem for working with F9 and F9-diff in EM-3, it provides a convenient assay for identifying molecules that support their growth at low density. Using this assay, we have determined that laminin, a newly isolated glycoprotein of basement membranes, significantly improves the growth and short-term survival of both F9 and F9-diff. However, addition of laminin to EM-3 is insufficient to promote the clonal growth of these cell types. Our findings also indicate that laminin promotes the attachment of F9 and F9-diff in defined media. On the basis of our results, we propose an attachment function for laminin during the early stages of mammalian development.