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J Miller

Publications and source records attributed to J Miller.

At least 523 records · Page 29Linked to original sources
PubMed1994

Recombinant adeno-associated virus-mediated gene transfer into hematopoietic progenitor cells.

Recombinant adeno-associated viruses (rAAV) containing only the inverted terminal repeats (ITR) from the wild-type virus are capable of stable integration into the host cell genome, and expression of inserted genes in cultured cells. We have now defined the ability of rAAV to introduce genes into primary hematopoietic progenitors. A vector was constructed containing the coding sequences for beta-galactosidase (beta-gal), including a nuclear localization signal, under the control of a strong viral promotor. Infectious vector particles were prepared by cotransfection of the vector plasmid with a second plasmid that contained the coding sequences for AAV proteins into adenovirus-infected human embryonic kidney cells. These vector preparations transferred and expressed the beta-gal gene in human K562 erythroleukemia and Detroit 6 cells. Positive immunoselection yielded a population of enriched CD34+ cells that were transduced with the rAAV beta-gal vector. Nuclear localized enzyme expression was documented in 60% to 70% of infected cells. Progenitor-derived colonies that developed after 2 weeks in clonogenic cultures were shown to have viral-associated DNA at an estimated copy number of 1 to 2 per cell using a semiquantitative polymerase chain reaction (PCR) method. Integration of AAV into hematopoietic progenitors was documented using wild-type virus, as its genome may integrate at a preferred site on chromosome 19. Our data suggest that rAAV will transfer and express genes in primitive hematopoietic progenitors with high frequency, and support the development of this vector system for therapeutic gene transfer.

Adenoviruses, Human↗
PubMed1994

Characterization of proteoglycans synthesized by murine embryonal carcinoma cells (P19) reveals increased expression of perlecan (heparan sulfate proteoglycan) during neuronal differentiation.

Proteoglycans (PGs) incorporated into cell layer and secreted into media were characterized during retinoic acid-induced neuronal differentiation of cultured P19 murine embryonal carcinoma cells. Heparan sulfate significantly increased (P < 0.01) in cell layer following neuronal differentiation of P19 cells by 3.9-fold. CL-4B gel chromatography revealed the major PGs present in cell layer of stem cells eluted as a broad peak with a Kav = 0.65, and was susceptible to chondroitin ABC lyase. The chondroitin ABC lyase resistant material eluted as a broad peak between Kav = 0.40 and Kav = 0.60, and was only partially digested with heparitinase/heparinase (with resistant material eluting at Kav = 0.70). Therefore, the cell layer of stem cells contained primarily chondroitin sulfate/dermatan sulfate (CS/DS) PGs, with lesser amounts of heparan sulfate proteoglycans (HSPGs). This was confirmed by SDS-PAGE. The CS/DS PGs in the cell layer of stem cells had an apparent M(r) of approximately > 200 kDa, and the HSPGs had an apparent M(r) of approximately 140-230 kDa. In contrast, the major PGs in the cell layer of neurons consisted primarily of HSPGs, with only a minor proportion of CS/DS PGs. Furthermore, both gel filtration chromatography and SDS-PAGE analysis revealed a larger HSPG in the cell layer of neurons (Kav = 0.3-0.6 on CL-4B following chondroitin ABC lyase digestion; M(r) 170 kDa- > 400 kDa on SDS-PAGE) in comparison to stem cells (Kav = 0.4-0.6 on CL-4B following chondroitin ABC lyase digestion; M(r) 140-230 kDa on SDS-PAGE). Likewise, the major PGs secreted into media of stem cells consisted almost exclusively of CS/DS PGs, with lesser amounts of HSPGs, whereas an increase in HSPGs in the media of neurons was apparent. Western, Northern, and immunocytochemical analysis demonstrated that mRNA transcript and protein levels for a specific HSPG (i.e., perlecan) markedly increased in cell layer following P19 neuronal differentiation. Perlecan core protein was identified by Western blot analysis using specific monoclonal and polyclonal antibodies, as a large HSPG with a core protein of apparent M(r) approximately 370-400 kDa, and was observed primarily in extracts from neurons. Northern blot analysis with a cDNA to perlecan revealed a significant (P < 0.01) 12.7-fold increase in expression of perlecan in neurons (day 9) in comparison to stem cells. The increase in perlecan message during P19 neuronal differentiation was concomitant with a significant (P < 0.01) 26.3-fold increase in message for beta-amyloid precursor protein (beta PP).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

A single amino acid mutation enhances the thermal stability of Escherichia coli malate dehydrogenase.

The stability of wild-type Escherichia coli malate dehydrogenase was compared with a mutant form of the enzyme with the amino acid residue at position 102 changed from arginine to glutamine. The mutation occurs on the underside of a mobile loop which closes over the active-site cleft on formation of the enzyme/cofactor/substrate ternary complex. The mutant enzyme is kinetically compromised while the wild-type enzyme is highly specific for oxaloacetate. The mutant enzyme was shown to be more resistant to irreversible thermal denaturation by thermal inactivation experiments and high-sensitivity differential scanning calorimetry than the wild-type enzyme. In contrast, resistance of both enzymes to reversible unfolding in guanidinium chloride was similar. Circular dichroic spectropolarimetry shows the secondary structures of the enzymes are similar but there is a demonstrable difference in tertiary structure. From the position of the mutation, it is conjectured that the substitution on a mobile surface loop results in partial closure of the loop and greater resistance to thermal inactivation of the mutant enzyme. However, molecular modelling combined with circular dichroic spectropolarimetry indicate that the mutation may have a more widespread effect on the structure than simply partial closure of the mobile surface loop as the environment of distant tyrosine residues is altered. Resistance of the wild-type enzyme to thermal inactivation can be increased by cofactor addition, which may have the effect of partial closure of the mobile surface loop, but has little effect on the mutant enzyme.

Arginine↗
PubMed1994

Energetic basis for structural preferences in 5/6-hydroxy-5,6-dihydropyrimidines: products of ionizing and ultraviolet radiation action on DNA bases.

The structures of all diastereoisomers of 5/6-hydroxy-5,6-dihydropyrimidines have been optimized with ab initio quantum chemical calculations using a 6-31G basis set. The energies of the optimized structures were calculated at the MP2/6-31G* level. The hydroxyl group prefers an equatorial over an axial orientation at the C(5) position of pyrimidines by 3-4 kcal/mol. At the C(6) position, the axial orientation of hydroxyl is preferred by 3-4 kcal/mol. The factors responsible for the different preferences result from dipolar intramolecular interactions between the hydroxyl and C(4) = O(4) on the one hand, and the N(1)-H(1) on the other hand. As a consequence of these structural preferences, the pseudo axial positions at C(5) and C(6), which are perpendicular to the molecular plane, can be occupied by different substituents. These pseudo axial groups are expected to be a major source of distortions to DNA structure with more bulky groups having a greater effect. This may constitute a structural basis for interpretation of experimental results on the biological consequences of pyrimidine lesions. The conclusions drawn from the calculations correlate well with experimental observations on the biological activities of thymine lesions.

Calorimetry↗
PubMed1994

Structure-function studies of DNA damage using ab initio quantum mechanics and molecular dynamics simulation.

Studies of ring-saturated pyrimidine base lesions are used to illustrate an integrated modeling approach that combines quantum-chemical calculations with molecular dynamics simulation. Electronic structure calculations on the lesions in isolation reveal strong conformational preferences due to interactions between equatorial substituents to the pyrimidine ring. Large distortions of DNA should result when these interactions force the methyl group of thymine to assume an axial orientation, as is the case for thymine glycol but not for dihydrothymine. Molecular dynamics simulations of the dodecamer d(CGCGAATTCGCG)2 with and without a ring-saturated thymine lesion at position T7 support this conclusion. Implications of these studies for recognition of thymine lesions by endonuclease III are also discussed.

Base Sequence↗
PubMed1994

Characterization of a monoclonal antibody recognizing an epitope designated as canine leukocyte-associated antigen.

An IgG1 monoclonal antibody (mAb), designated as 15F1.5, was generated against surface determinants of a dog peripheral blood-derived PHA-induced IL-2-dependent T cell line. It reacted with 65-80% of peripheral blood mononuclear cells (PBMCs), 90-95% of polymorphonuclear cells (PMNs), 65-70% of thymocytes, 85-95% of Thy-1 positive cells and 85-95% of IL-2-dependent T lymphoid cells in flow cytometry. It was nonreactive with peripheral blood red cells and platelets. It immunoprecipitated 95 and 150 Kd proteins derived from detergent solubilized lymphocyte membranes. Indirect immunofluorescent and immunoperoxidase staining of frozen tissue sections demonstrated positive reactivity to cells in lymphoid but not nonlymphoid tissues. The 15F1.5 antibody was not directly mitogenic for PBMC's. It caused significant decrease (P < or = 0.05) in the lymphoproliferative response to T-dependent B cell mitogens, such as pokeweed mitogen (PWM) and staphage lysate (SPL), without significant effects on responses to the T cell mitogens, phytohemagglutinin (PHA), and concanavalin A (Con A). The mixed lymphocyte culture (MLC) response and both the proliferative and effector arms of the cell-mediated cytotoxicity reactions (CMC) were inhibited in a dose-dependent manner. The mAb also inhibited the auto- and allolymphoproliferative reactivity of mixed lymphocyte kidney or islet cell cultures (MLKC and MLIC), and the adhesion of T lymphoblasts and PMA-treated PMNs to endothelial cells. In vivo administration of the 15F1.5 (20 mg/day for 5 days) caused an immediate and prolonged reduction in MLC responses, associated with cell binding of the mAb to PBMC and epitope modulation during the course of treatment, as indicated by flow cytometry. These results suggest that 15F1.5 is an immunomodulating antibody reacting with canine LFA-1. Thus, this mAb would be useful in studying the role of LFA-1/ICAM-1 in graft rejection as well as other inflammatory responses. It would also allow the use of an animal model to investigate the immunoregulatory effects of in vivo administration of anti-CD11/CD18 antibodies in organ/tissue transplants.

Animals↗
PubMed1994

Bovine papillomavirus E1 protein affects the host cell cycle phase fractions.

C127 murine fibroblast cells were electroporated with a bovine papillomavirus E1 protein expression vector and examined by flow cytometry. E1 expressing cells (E1+) within the total cell population were distinguished from nonexpressing cells (E1-) by immunofluorescent staining with anti-E1 serum and a fluorescein-conjugated second antibody. Under conditions of saturation with the first and second antibodies, the specific green fluorescence reflected the level of intracellular E1 protein. Simultaneous staining with a DNA-specific dye, propidium iodide (PI), enabled the cell cycle distributions for the E1+ and E1- cell populations to be determined. It was found that the E1+ subpopulation had a reduced percentage of cells in G1 phase and an increased percentage of G2+M phase cells, compared to the E1- subpopulation. There was no significant difference in overall doubling time or percentage of noncycling cells in the E1+ vs. E1- populations, indicating that the change in cell cycle distribution was not due to a general activation or inhibition of cell growth by E1. Direct measurement of cell cycle phase fractions confirmed that the G1 phase was decreased and the G2+M phase was increased in E1 expressing cells. As these observations were made in the absence of other viral proteins or viral DNA replication, it suggests that the E1 protein exerts an effect on the host cell independent of its direct role in viral DNA replication. Thus, E1 may interact directly with the host cell cycle regulatory machinery.

Amino Acid Sequence↗
PubMed1994

Substrate specificity of Fpg protein. Recognition and cleavage of oxidatively damaged DNA.

The 8-oxoguanine-DNA glycosylase of Escherichia coli, also known as formamidopyrimidine-DNA glycosylase (Fpg protein), has N-glycosylase and AP-lyase activities. This enzyme repairs oxidative DNA damage by efficiently removing formamidopyrimidine lesions and 8-oxoguanine residues from DNA. Defined oligodeoxynucleotides containing various 8-oxopurines were used to examine the substrate specificity of Fpg protein and to establish the role of functional groups in DNA on damage recognition and catalysis. Binding affinities of Fpg protein were established for duplex oligodeoxynucleotides containing 8-oxo-2'-deoxyguanine, 8-oxo-2'-deoxyadenine, 8-oxo-2'-deoxynebularine, 8-oxo-2'-deoxyinosine, abasic sites, and a ring-open adduct of C8-aminofluorene guanine. The C8 keto group of 8-oxodG:dC presents in the major groove and is correlated with tight binding (Kd = 8.9 nM). Binding is much weaker when the C8 keto functional group is in the minor groove, as in 8-oxodG:dA (Kd = 340 nM). Km and Vmax were determined for the cleavage reaction. Specificity constants (Kcat/Km) are consistently higher for oligodeoxynucleotide duplexes containing 8-oxopurines with C6 and C8 keto groups, as in 8-oxodG:dC and 8-oxodI:dC, where Kcat/Km are 9.3 and 18 min-1 nM x 10(-3), respectively. 8-oxodN:dC lacks the C6 keto group; the specificity constant is 0.024 min-1 nM x 10(-3). Taken together, our data suggest that the C8 keto group of 8-oxodeoxyguanine and the carbonyl moiety of formamidopyrimidine enable Fpg protein to recognize and bind duplex DNA containing these modified bases. An enzyme-catalyzed reaction involving the C6 keto group of the substrate leads to removal of these lesions. A mechanism involving protonation at O-6 of 8-oxoguanine is proposed to account for the N-glycosylase activity of this enzyme.

Catalysis↗
PubMed1994

Depletion of hepatitis C virus from procured kidneys using pulsatile perfusion preservation.

The safety of the use of kidneys procured from a hepatitis C virus (HCV)-positive cadaver donors in transplantation has recently been the subject of controversy. One factor that is important in determining the transmission of the virus and/or viral liver disease is the total viral inoculum to which the renal allograft recipient is exposed as a result of the transplant. We have studied the effect of a standard pulsatile renal preservation procedure and variations of it on the number of viral copies in organs from HCV-positive donors. An HCV-RNA quantitative reverse transcription-polymerase chain reaction (RT-PCR) method was utilized with a recombinant competitive inhibitor substrate added after cDNA synthesis with the PCR primers within the relatively non-polymorphic 5' untranslated region of the HCV genome. Additionally, strain specificity was found to be detectable using a modification of the technique of restriction fragment-length polymorphism (RFLP-PCR), so that virus from the organ donor could be specifically identified and quantified in the recipient. It was observed that standard preservation procedures using pulsatile perfusion were able to eliminate 75% of the virus from the organ in 20 hr. By modifying this procedure to include additional wash steps and a second pulsatile perfusion, greater than 99% of the virus could be eliminated from the kidney. In a related study, we used quantitative PCR to study requirements for filtration of the virus using HCV-positive serum. It was found that a high-flow-rate ultrafilter with a molecular weight cut-off (MWCO) of 300,000 daltons placed in series to the preservation apparatus was very efficient in eliminating the virus from perfusion solution in less than 2 hr. It can therefore be proposed that with the use of these molecular techniques, pulsatile perfusion coupled with additional viral depletion steps (dilution, and/or filtration) may allow the practical reduction of HCV transmission risk in recipient follow-up studies. The means are thereby presented for similar manipulation of other known or, as yet, unknown transmissible agents.

Base Sequence↗
PubMed1994

Quantitative switch in integrin expression accompanies differentiation of F9 cells treated with retinoic acid.

F9 embryonal carcinoma cells resemble epithelial cells when in monolayer culture. After treatment with retinoic acid these cells differentiate into fibroblastic-like cells in a sequence that has been modeled as the mammalian equivalent of the differentiation from stem cells of the inner cell mass to parietal endoderm. This study examined the changes in integrin subtypes that accompany retinoic acid-induced differentiation of F9 cells. Although several integrins were found to be present on the surface of F9 cells and retinoic acid-induced (RA) cells, the two dominant integrins were alpha 3 beta 1 and alpha 5 beta 1. Differentiation of F9 cells resulted in about 10- to 25-fold increase in the amount of alpha 3 beta 1 integrin protein as measured by immunoprecipitation of cell surface labeled material. There was a corresponding several-fold reduction of alpha 5 beta 1 protein. The concentration of alpha 3 mRNA was about the same in F9 and RA cells while the concentration of alpha 5 mRNA dropped several-fold after retinoic acid treatment. Thus alpha 3 regulation appeared to be largely posttranscriptional while the drop in alpha 5 protein may have been a result of transcriptional down-regulation. Quantitative measurement of adhesion suggested that most of the F9 and RA cell-substrate adhesion to fibronectin or laminin is mediated by these integrins. They are the dominant integrins present, and antibodies to either these integrins or to the substrate blocked the adhesion. Despite the large switch in integrin subtype protein expression there was little difference between the two cell types in initial cell interactions when adhesive affinities were measured quantitatively. Also there was no difference between the two phenotypes in rate of initial adhesive strengthening. The phenotypic difference was first observed with later events in the attachment and spreading of the RA-treated cells to the substrate. These results show that retinoic acid treatment alters the amounts of alpha 5 and alpha 3 integrin subunits during the F9 to RA phenotypic switch. The data show that these integrins are important in the cell-substrate adhesion to fibronectin and laminin. They show, however, that the phenotypic changes observed with differentiation are not associated with the initial preferential adhesions to the substrate, but rather with consequences that alter the cytoskeletal architecture of the cell.

Animals↗
PubMed1994

Nuclear shape and prognosis following orchiectomy in stage D2 prostate cancer.

In this study, we have examined whether tumor grade and morphometric nuclear features can predict the outcome of treatment by orchiectomy in patients with stage D2 prostate cancer. Two outcome groups based on duration of survival postorchiectomy were examined, a bad outcome group of 63 patients who died from prostate cancer within 12 months and a good outcome group of 34 patients who survived beyond 5 years. Tumors were histologically classified as well (17%), moderate (17%), or poorly differentiated (66%). Tumor grade and patient outcome were significantly associated (Mann-Whitney test; P < 0.005), with 76% of poorly differentiated tumors in the bad outcome group, and 65% of well-differentiated tumors in the good outcome group. Using discriminant function analysis, tumor grade correctly predicted outcome in 70% of cases. A statistically significant difference was also detected in nuclear shape values between the two outcome groups (P < 0.05) and histological grades (P < 0.05). Using discriminant function analysis, 51% of cases were correctly classified into outcome groups using nuclear shape factors, a figure which rose to 65% when all nuclear morphometric features were used. This demonstrates that nuclear morphometric features are of no clinical value in predicting the outcome of treatment in stage D2 disease. Furthermore, these evaluations cannot select patients who might be spared orchiectomy on the basis of a predicted poor response. However, nuclear shape and variance measurements of benign glandular epithelial cells within cancerous prostates were significantly different from those of malignant cells (P < 0.005). We conclude that, while video image analysis of prostatic nuclear shape can reliably discriminate between benign and malignant cells, nuclear morphometric features are of minimal prognostic value in men with stage D2 prostate cancer treated by androgen ablation.

Aged↗
PubMed1994

The bovine papillomavirus E1 protein alters the host cell cycle and growth properties.

A stable E1-expressing cell line, CE1, was developed to investigate the effect of bovine papillomavirus E1 protein on host cell growth. Expression of E1 in CE1 cells is under control of the dexamethasone-inducible mouse mammary tumor virus LTR promoter. Flow cytometry was used to determine the intracellular levels of E1 in CE1 cells in parallel with cell cycle distributions and cell growth parameters. CE1 cells expressed a basal level of E1 that was increased following exposure to increasing concentrations of dexamethasone. As E1 expression increased, the following effects on cell growth were observed: (1) the overall cell generation time increased and (2) the duration of G1 + G0 phases increased slightly while the duration of G2 + M phases increased twofold. The appearance of a cell subpopulation with a greater than G2 phase DNA content was also observed in E1-expressing cells. Removal of dexamethasone resulted in a return of E1 levels to the basal state with a concomitant restoration of both cell growth properties and cell cycle phase distributions. All of the observed effects were seen in the absence of both other papillomaviral proteins and papillomaviral DNA replication. We conclude that E1 is sufficient to negatively affect host cell growth, with a prominent effect observed in the G2 + M phases.

Animals↗
PubMed1994

Substitution of the amino acid at position 102 with polar and aromatic residues influences substrate specificity of lactate dehydrogenase.

The Gln residue at amino acid position 102 of Bacillus stearothermophilus lactate dehydrogenase was replaced with Ser, Thr, Tyr, or Phe to investigate the effect on substrate recognition. The Q102S and Q102T mutant enzymes were found to have a broader range of substrate specificity (measured by kcat/Km) than the wild-type enzyme. However, it is evident that either Ser or Thr at position 102 are of a size able to accommodate a wide variety of substrates in the active site and substrate specificity appears to rely largely on size discrimination in these mutants. The Q102F and Q102Y mutant enzymes have low catalytic efficiency and do not show this relaxed substrate specificity. However, their activities are restored by the presence of an aromatic substrate. All of the enzymes have a very low catalytic efficiency with branched chain aliphatic substrates.

Amino Acid Sequence↗
PubMed1994

Pneumonia in a nursing home.

The authors studied nursing home residents serologically to determine whether atypical organisms were causes of radiologic pneumonia. The study was conducted at the Wisconsin Veterans Home, a facility with on-site microbiology and x-ray. Over one year, serologic examinations for Legionella, Mycoplasma, and Chlamydia were conducted for the residents who had pneumonia. Cultures and mortality were reviewed. Fifty-six episodes were studied (mean resident age 78 years). There was no fourfold titer change. Seventeen quality sputum specimens revealed Streptococcus pneumoniae (5), normal flora (4), Hemophilus influenzae (4), Moraxella catarrhalis (3), Staphylococcus aureus (1), and beta-hemolytic Streptococcus, not group A (1). The two-month mortality was 21%. This study did not result in serologic confirmation of atypical organisms' causing pneumonia. Antibiotic choice should be based on coverage of prevalent organisms, including Hemophilus influenzae, Moraxella, and Staphylococcus, as well as clinical features.

Aged↗
PubMed1994

Endosomal localization of MHC class II-invariant chain complexes.

CD4-positive T cells recognize foreign antigens displayed on the surface of antigen-presenting cells as small peptides bound to MHC class II molecules. Thus, the ability of antigen-presenting cells to generate these class II-peptide complexes is central to the initiation and regulation of immune responses. Class II predominantly associates with peptides derived from soluble protein antigens that are internalized and degraded within endosomal compartments. It is within these endosomal compartments that class II encounters and binds antigenic peptides. A number of signals have been implicated in directing the intracellular transport of class II to endosomes. These include sequences within class II itself and within the class II-associated invariant chain (Ii)

Antigen Presentation↗
PubMed1994

Successful and unsuccessful sites of radiofrequency catheter ablation of accessory atrioventricular connections.

Local electrograms from 47 consecutive patients who underwent successful radiofrequency catheter ablation of 49 accessory atrioventricular (AV) connections were analyzed. One hundred twenty-two local electrograms were recorded at 27 successful and 95 unsuccessful sites immediately before radiofrequency catheter ablation of 27 manifest accessory AV connections during preexcited sinus rhythm or atrial pacing. Continuous electric activity was found in 96% of successful sites versus 71% of unsuccessful sites (p < 0.01). Possible accessory pathway (AP) potentials were present only in 15% of successful and 2% of unsuccessful sites, respectively (p < 0.05). All measured time intervals were significantly shorter for successful sites as compared to unsuccessful sites of ablation of manifest accessory AV connections. Unipolar electrograms from the tip of the ablation catheter of each successful and unsuccessful ablation site were available for the last 16 patients with manifest accessory AV connections. A PQS pattern of the unipolar electrogram was associated with a higher success rate, whereas a PrS pattern never resulted in successful ablation of an accessory AV connection. Multivariate logistic regression analysis of the local electrogram characteristics of rapidly conducting, concealed accessory AV connections revealed the interval between the onset of the local ventricular and atrial electrogram (VoAo interval) as the only independent variable associated with successful sites for radiofrequency catheter ablation. The only study patient with a slowly conducting, concealed accessory AV connection underwent successful ablation with the first lesion of radiofrequency energy at the site with the shortest VoAo interval. We conclude that (1) the shortest local AV intervals and local ventricular electrograms preceding the earliest onset of the delta wave in any surface lead are predictive of successful ablation of manifest accessory AV connections; (2) the shortest local VA intervals during orthodromic AV reentry tachycardia or right ventricular pacing are predictive of successful ablation of concealed accessory AV connections; and (3) unipolar recordings from the tip of the ablation catheter should be recorded routinely during mapping of manifest accessory AV connections to identify appropriate target sites for radiofrequency energy applications.

Action Potentials↗
PubMed1994

Visualizing collagen fibril growth.

Collagen fibrils are among the most abundant protein polymers in living organisms. While the longitudinal packing of molecules in the fibrils has been agreed on for many years, there is continuous disagreement over the lateral packing. In this work, we describe a set of computer graphics programs that can be used to visualize fibril packing and simulate fibril growth. An example of a model and simulation are presented.

Collagen↗