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Biomedical subjects

M Lopez

Publications and source records attributed to M Lopez.

At least 55 records · Page 3Linked to original sources

Novel, soluble isoform of the herpes simplex virus (HSV) receptor nectin1 (or PRR1-HIgR-HveC) modulates positively and negatively susceptibility to HSV infection.

A novel member of the nectin family, nectin1gamma, was molecularly cloned. The cDNA has the same ectodomain as nectin1alpha and nectin1beta, the two known transmembrane isoforms that serve as receptors for herpes simplex virus (HSV) entry into human cell lines (nectin1alpha and nectin1beta, also called PRR1-HveC and HIgR, respectively). The 1.4-kb transcript, which originated by alternative splicing, is expressed in human cell lines, and appears to have a narrow distribution in human tissues. The sequence does not have a hydrophobic anchoring region, and the protein is secreted in the culture medium of cells transfected with the cDNA. Nectin1gamma, purified from culture medium, can compete with membrane-bound nectin1beta and reduce HSV infectivity. The expression of nectin1gamma cDNA in cells resistant to HSV infection and lacking HSV receptors enables HSV to enter the cell, which implies that it is present at the cell surface. Thus, nectin1gamma has the potential both to mediate and to reduce HSV entry into cells.

Amino Acid Sequence↗

Chimeric nectin1-poliovirus receptor molecules identify a nectin1 region functional in herpes simplex virus entry.

Human nectin1 (hNectin1), an adhesion molecule belonging to the nectin family of the immunoglobulin superfamily, mediates entry of herpes simplex virus (HSV) into cells. The hNectin1 domain that mediates virus entry into cells and also binds glycoprotein D (gD) has been localized to the first N-terminal V-type domain. The poliovirus receptor (PVR) is a structural homolog to nectins, but it cannot function as an HSV entry receptor. hNectin1-PVR chimeras were constructed to functionally locate the site on hNectin1 involved in HSV entry (HSV entry site). The epitope recognized by monoclonal antibody (MAb) R1.302, which is able to block HSV entry, was also located. The chimeric receptors were designed to preserve the overall structure of the V domain. The HSV entry activity mapped entirely to the hNectin1 portion located between residues 64 and 94 (64-94), likely to encode the C, C', and C" beta-strands and intervening loops. In turn, this site consisted of two portions: one with low-level basal activity for HSV entry (77-94), and one immediately upstream (residues 64 to 76) which greatly enhanced the HSV entry activity of the downstream region. The gD-binding site mapped substantially to the same site, whereas the MAb R1.302 epitope also required a further downstream portion (95-102). The involvement of the 64-76 portion is at difference with previous indirect mapping results that were based on competitive binding studies (C. Krummenacher et al., J. Virol. 74:10863-10872, 2000). The A, A', B, D, E, F, and G beta-strands and intervening loops did not appear to play any role in HSV entry. According to the predicted three-dimensional structure of PVR, the C C' C" site is located peripherally in the V domain and very likely represents an accessible portion at the cell surface.

Amino Acid Sequence↗

Attenuation of age-related declines in glucagon-mediated signal transduction in rat liver by exercise training.

This study investigated alterations in glucagon receptor-mediated signal transduction in rat livers from 7- to 25-mo-old animals and examined the effects of exercise training on ameliorating these changes. Sixty-six young (4 mo), middle-aged (12 mo), and old (22 mo) male Fischer 344 rats were divided into sedentary and trained (treadmill running) groups. Isolated hepatic membranes were combined with [(125)I-Tyr(10)]monoiodoglucagon and nine concentrations of glucagon to determine maximal binding capacity (B(max)) and dissociation constant (K(d)). No alterations were found in B(max) among groups; however, middle-aged trained animals had significantly higher glucagon affinity (lower K(d); 21.1 +/- 1.8 nM) than did their untrained counterparts (50.2 +/- 7.1 nM). Second messenger studies were performed by measuring adenylyl cyclase (AC) specific activity under basal conditions and with four pharmacological stimulations to assess changes in receptor-dependent, G protein-dependent, and AC catalyst-dependent cAMP production. Age-related declines were observed in the old animals under all five conditions. Training resulted in increased cAMP production in the old animals when AC was directly stimulated by forskolin. Stimulatory G protein (G(s)) content was reduced with age in the sedentary group; however, training offset this decline. We conclude that age-related declines in glucagon signaling capacity and responsiveness may be attributed, in part, to declines in intrinsic AC activity and changes in G protein [inhibitory G protein (G(i))/G(s)] ratios. These age-related changes occur in the absence of alterations in glucagon receptor content and appear to involve both G protein- and AC-related changes. Endurance training was able to significantly offset these declines through restoration of the G(i)/G(s) ratio and AC activity.

Adenylyl Cyclases↗

Docetaxel in patients with anthracycline-resistant advanced breast cancer.

OBJECTIVE: To better determine docetaxel activity in patients with well-defined anthracycline-resistant breast cancer. METHODS: From October 1996, we carried out a phase II trial in 69 heavily pretreated patients with advanced breast cancer with docetaxel 100 mg/m(2) by a 1-hour infusion on day 1, with cycles repeated every 3 weeks. Patients were classified as having primary anthracycline resistance (n = 32), secondary anthracycline resistance (n = 7), anthracycline pretreatment (n = 22) or no anthracycline pretreatment (n = 8). RESULTS: Among 68 evaluable patients, we observed 6 (9%) complete responses and 27 (40%) partial responses, for an overall response rate of 49% (95% confidence interval 37-61%); the disease remained stable in 17 patients (25%). Responses according to the above subgroups were as follows: primary anthracycline resistance 41%, secondary anthracycline resistance 43%, anthracycline pretreatment 64% and no anthracycline pretreatment 43%. The median time to response, median time to progression and median overall survival were 2, 7 and 10 months, respectively. Myelosuppression was the dose-limiting toxicity, with grade 4 neutropenia occurring in 47% of the patients and neutropenic fever in 12%. G-CSF was added in the case of grade 4 febrile neutropenia; a 25% reduction in the dose of docetaxel was required in 4 patients. Other side effects were mild. CONCLUSIONS: The results of the present trial confirm the high activity of docetaxel in heavily pretreated patients with advanced breast cancer, including those with strictly defined anthracycline resistance.

Adult↗

Allergen immunotherapy.

Allergen immunotherapy has been used since the early 1900's for the treatment of allergic syndromes. The efficacy of immunotherapy for the treatment of anaphylaxis caused by the sting of the Hymenoptera class of insects, allergic rhinoconjunctivitis, and the allergic component of bronchial asthma has been clearly demonstrated in numerous well-designed, placebo-controlled trials. Many recent advances in our understanding of the cellular and molecular basis of the allergic response have permitted the development of innovative experimental approaches that very likely will improve the control of the allergic response in the future.

Adult↗

Hypersensitivity pneumonitis: a comprehensive review.

Hypersensitivity pneumonitis is a dynamic and heterogeneous group of diseases resulting from inhalational exposure to a variety of organic and inorganic dusts. In the United States, it has predominantly been considered an occupational disease, such as in farmer's lung, bagassosis, and in the plastics and paint industry with isocyanate exposure. In Japan, however, the most common exposure to antigen has been associated with the home environment. All susceptible patient populations are at potential risk to develop this disease under appropriate antigen exposure. The clinical course can be acute, subacute, or chronic depending on the nature of the antigen and the circumstances under which exposure occurs. If unrecognized, any stage of disease has the potential to progress to endstage pulmonary fibrosis. Proper antigen identification and avoidance requires that the physician be keenly aware of its existence and the importance of the detailed occupational and home environmental history. Without a high degree of suspicion, this disease can be easily overlooked and misdiagnosed as another type of inflammatory lung disease. Although the immunologic mechanisms mediating this illness are complex and poorly understood, strict avoidance of the provocative antigen is required for optimal long-term outcome.

Alveolitis, Extrinsic Allergic↗

[Intramedullary tumors].

Intramedullary tumours represent 2-4% of all central nervous system tumours. Clinical presentation can adopt any aspect of slow medullar compression. Often benign, these tumours are mostly of glial origin: ependymomas or astrocytomas. Diagnosis has been revolutionised by magnetic resonance imaging, which allows a precise analysis of the tumour with differentiation between the consistent portion and its satellite cysts. Surgery remains the treatment of choice. Total removal can often be achieved and no further complementary treatment is justified, except in proven malignancy. If resection has been partial, radiotherapy remains controversial as non-deprived of untoward effects, when delivered at efficient dose. Long term follow-up is mandatory, as there are late recurrences or secondary aggravations, evolving on their own. As post-therapeutic clinical state is highly correlated with the pretherapeutic state, intramedullary tumours are to be considered as medical emergencies.

Astrocytoma↗

An association study of bipolar mood disorder (type I) with the 5-HTTLPR serotonin transporter polymorphism in a human population isolate from Colombia.

The short variant of a functional length polymorphism in the promoter region of the serotonin transporter has been associated with several behavioural and psychiatric traits, including bipolar mood disorder. The same short allele has also been implicated as a modifier of the bipolar phenotype. Here we evaluate the etiologic/modifier role of this polymorphism in a case (N=103) / control (N=112) sample for bipolar mood disorder (type I) collected from an isolated South American population. We did not detect an association between bipolar disorder and the 5-HTT promoter polymorphism in this sample. However, an excess of the short allele was seen in younger cases and in cases with psychotic symptoms. When combined with data from the literature, the increased frequency of the short allele in patients with psychotic symptoms was statistically significant.

Age of Onset↗

Human nectin3/PRR3: a novel member of the PVR/PRR/nectin family that interacts with afadin.

We have isolated nectin3/PRR3, the fourth human member of the nectin/PRR family, also described as the alpha herpes virus receptor family. Nectin/PRR members are adhesion molecules expressed at intercellular junctions. Nectin3/PRR3 is a transmembrane protein, whose extracellular region contains three Ig-like domains (V, C and C) and shares approximately 30% identity with the other members. It is mainly expressed in testis and placental tissues. SDS-PAGE analyses demonstrate that nectin3/PRR3 has a molecular weight of 83kDa. Nectin1/PRR1L and nectin2/PRR2S and L were found to be specifically expressed at the intercellular junctions. This localization is in part due to the interaction of the C-terminal part of these receptors (ended by the consensus sequence A/EXYV) and the PDZ domain of afadin. In this report we demonstrate that the nectin3/PRR3 receptor carries the A/EXYV consensus sequence and interacts in vivo with both long and short isoforms of afadin. These results suggest that the human nectin3/PRR3 is a new afadin-associated molecule.

Amino Acid Sequence↗

Cdc42 is required for PIP(2)-induced actin polymerization and early development but not for cell viability.

BACKGROUND: Cdc42 and other Rho GTPases are conserved from yeast to humans and are thought to regulate multiple cellular functions by inducing coordinated changes in actin reorganization and by activating signaling pathways leading to specific gene expression. Direct evidence implicating upstream signals and components that regulate Cdc42 activity or for required roles of Cdc42 in activation of downstream protein kinase signaling cascades is minimal, however. Also, whereas genetic analyses have shown that Cdc42 is essential for cell viability in yeast, its potential roles in the growth and development of mammalian cells have not been directly assessed. RESULTS: To elucidate potential functions of Cdc42 mammalian cells, we used gene-targeted mutation to inactivate Cdc42 in mouse embryonic stem (ES) cells and in the mouse germline. Surprisingly, Cdc42-deficient ES cells exhibited normal proliferation and phosphorylation of mitogen- and stress-activated protein kinases. Yet Cdc42 deficiency caused very early embryonic lethality in mice and led to aberrant actin cytoskeletal organization in ES cells. Moreover, extracts from Cdc42-deficient cells failed to support phosphatidylinositol 4,5-bisphosphate (PIP(2))-induced actin polymerization. CONCLUSIONS: Our studies clearly demonstrate that Cdc42 mediates PIP(2)-induced actin assembly, and document a critical and unique role for Cdc42 in this process. Moreover, we conclude that, unexpectedly, Cdc42 is not necessary for viability or proliferation of mammalian early embryonic cells. Cdc42 is, however, absolutely required for early mammalian development.

Actins↗

Experience-dependent decrease in synaptically localized Fra-1.

The Fos family of transcription factors has been repeatedly shown to participate in the long-term neural responses associated with a variety of physiological stimuli, including activity-dependent plastic processes. Quite recently, several transcription factors have been found in synaptic regions, localized in dendrites and presynaptic terminals. Here we show that the transcription factor Fos-related antigen-1 (Fra-1) was detected in synaptosomes (Syn) and synaptic plasma membrane (SPM) fractions from the rat cerebral cortex and hippocampus as a single band migrating with M(r) 42-43 kDa. The 55-kDa c-Fos protein was also detected in syn and SPM fractions. Conversely, the inducible 62-65-kDa c-Fos is present in nuclear fractions from metrazole-treated animals (positive control), but not in Syn or SPM fractions. Furthermore, no Fra-2, Fos B or c-Jun immunoreactivities were detected in these same synaptic regions. DNA-mobility shift assays showed the presence of specific AP-1 binding activity in synaptic protein extracts. Immunoelectronmicroscopic analysis of cortical and hippocampal tissues revealed that Fra-1 and Fos-like immunoreactivities are localized in association with presynaptic plasma membranes. One trial inhibitory avoidance training, a hippocampal-dependent task, is associated with a time-dependent decrease (-31%) in Fra-1, but not in 55-kDa c-Fos, levels in hippocampal SPM fractions. In hippocampal homogenates, we do not detect significant changes in Fra-1 immunoreactivity, suggesting that this behavioural experience is probably accompanied by a subcellular redistribution of Fra-1 protein. These results suggest that Fra-1 may participate in the communication between synapse and the nucleus and in experience-dependent hippocampal plasticity.

Animals↗

The murine homolog of human Nectin1delta serves as a species nonspecific mediator for entry of human and animal alpha herpesviruses in a pathway independent of a detectable binding to gD.

The full-length cDNA of the murine homolog of human nectin1delta (mNectin1delta), also known as human poliovirus receptor related 1 (PRR1) or herpesvirus entry mediator C, was cloned and showed a >90% identity with its human counterpart. mNectin1delta is expressed in some murine cell lines, exemplified by NIH 3T3 and L cells, and in murine tissues. It mediates entry of an extended range of herpes simplex virus (HSV) strains, porcine pseudorabies virus (PrV), and bovine herpesvirus 1. A soluble form of the mediator blocked infectivity in mNectin1delta and human nectin1delta (hNectin1delta)-expressing cells, suggesting a physical interaction of the mediator with virions. The higher concentrations of soluble mNectin1 required to block infectivity relative to soluble hNectin1 suggest that the target of the two molecules is not identical. Entry of HSV, but not PrV, was blocked by soluble mNectin1delta in NIH 3T3 and L cells. Two features were unexpected. First, soluble mNectin1delta failed to physically interact with HSV glycoprotein D (gD) at a detectable level, although it interacted physically with virions. Second, coexpression of mNectin1delta and HSV gD did not restrict HSV or PrV infection, whereas coexpression of hNectin and gD did restrict infection, suggesting that mNectin1delta fails to be sequestered by HSV gD. We conclude that mNectin1delta serves as a species-nonspecific mediator for entry of the human and animal alphaherpesviruses. This activity, at least for HSV, is independent of a detectable binding to gD.

3T3 Cells↗

Infectiousness of Mycobacterium tuberculosis in HIV-1-infected patients with tuberculosis: a prospective study.

BACKGROUND: Previous studies concerning the relative infectiousness of HIV-1-positive individuals with pulmonary tuberculosis have produced conflicting results. Thus, we assessed the effect of HIV-1 on the infectiousness of Mycobacterium tuberculosis in a prospective study. METHODS: We organised in Santo Domingo, Dominican Republic, a cohort study of household contacts of HIV-1-positive and HIV-1-negative individuals with newly diagnosed pulmonary tuberculosis. Household contacts were assessed at their houses at baseline and followed up for 14 months for evidence of M tuberculosis infection and tuberculosis with a multi-step tuberculin skin test, anergy skin test, physical examinations, chest radiographs, and sputum smears. FINDINGS: Tuberculin induration of 5 mm or greater was seen in 153 (61%) of 252 household contacts of HIV-1-positive index cases and in 418 (76%) of 551 household contacts of HIV-1-negative index cases (odds ratio 0.49 [95% CI 0.35-0.67], p=0.00001). In multivariate logistic-regression analysis after allowance for between-household variation in tuberculin response, HIV-1 infection of the index case remained inversely associated with the tuberculin response of the household contacts (0.52 [0.29-0.93], p=0.02). When the analysis was restricted to household contacts aged between 2 years and 15 years the adjusted association remained significant (0.37 [0.14-0.98], p=0.04). Among household contacts who had a negative tuberculin skin test at baseline, conversion to tuberculin skin test positivity was less frequent among household contacts of HIV-1-positive index cases (cut-off > or =5 mm: 32/131 [24%] vs 71/204 [35%], p=0.05; cut-off > or =10 mm: 23/153 [15%] vs 55/245 [22%], p=0.07). INTERPRETATION: These data suggest that HIV-1-positive individuals with tuberculosis are less likely than HIV-1-negative individuals with tuberculosis to transmit M tuberculosis to their close contacts. No changes in the current policy regarding tuberculosis contact tracing are needed in the presence of HIV-1.

AIDS-Related Opportunistic Infections↗

Mothers' developmental expectations for young children in the Philippines.

The purpose of the study was to investigate the developmental timetables of rural and urban mothers in the Central Visayas, Philippines. Examined were mothers' expectations for children's development (physical/perceptual-motor, cognitive, and psychosocial) and mothers' child rearing practices, as influenced by four selected variables (child's gender and ordinal position, mother's education, and rural or urban residence). The total sample size was 303 mothers [153 of rural residence and 150 urban] in two provinces. Mothers responded to a structured questionnaire which was read to them aloud by trained interviewers who then recorded the responses. All the mothers had children between 4-6 years old; equal numbers of male and female children were included, and the entire economic and educational ranges were represented. MANOVA results showed significant main effects of all four variables on maternal expectations of child development and on maternal child rearing practices. Also, significant interaction effects of residential location and maternal education on mothers' expectations of children's physical/perceptual motor development were found (F[2, 256]=3.05, P=0.05). Significant interaction effects also were found of maternal education and the child's ordinal position (F[4,256]=2. 95, P=0.02) on maternal expectations of children's psychosocial development.

Adult↗

Lithium-induced context aversion in rats as a model of anticipatory nausea in humans.

In three experiments, rats received injections of lithium chloride (LiCl) before being exposed to a distinctive context. In a subsequent test, rats given access to sucrose solution in this context consumed less than control subjects given sucrose in another context that had been paired with a saline injection (Experiment 1), or was quite novel (Experiment 2). Experiment 3 demonstrated that a context that had been associated with LiCl would serve to block the acquisition of a conditioned flavor aversion when it was presented immediately after the injection on a flavor-LiCl trial. These results show that a procedure in which rats experience the adverse effects of a lithium injection in the presence of contextual cues is effective in endowing those cues with aversive properties. It is argued that the context evokes a state of conditioned nausea, and the parallel with the clinical phenomenon of anticipatory nausea and vomiting (ANV) in human patients is outlined.

Animals↗

5-Fluorouracil and folinic acid with or without CPT-11 in advanced colorectal cancer patients: a multicenter randomised phase II study of the Southern Italy Oncology Group.

PURPOSE: The combination regimen CPT-11 plus bolus and infusion 5-fluorouracil (5-FU) with high-dose leucovorin (hybrid regimen LV5FU2) has been tested for activity and toxicity against advanced colorectal carcinoma in a randomised, multicenter phase II trial. PATIENTS AND METHODS: A total of 102 chemotherapy-naïve patients were randomised in a 1:2 fashion to receive: leucovorin 100 mg/m2 administered as a two-hour infusion before 5-FU 400 mg/m2 as an intravenous bolus, and FU 600 mg/m2 as a 22-hour infusion immediately after 5-FU bolus injection repeated on days 1 and 2 (LV5FU2 regimen, arm A, 34 patients) or CPT-11 at 180 mg/m2 (150 mg/m2 for patients of age > or = 70 and < 75 years) only on day 1 immediately before LV5FU2 therapy (LV5FU2 + CPT-11 regimen, arm B 68 patients). Both treatments were repeated every two weeks. The presence of a calibration arm assured consistency and more realistic evaluation of results achieved with the LV5FU2 + CTP-II regimen. RESULTS: Thirty-three and sixty-four patients were evaluable in arm A and B, respectively. The overall response rate was 18% in arm A (95% CI: 7%-34%) and 40% in arm B (95% CI: 28%-52%). Median time to progression, median duration of response and survival were similar in both groups. Responders (CR + PR) survived statistically longer than non-responders only in arm B (20 vs. 10 months, P = 0.0016). All patients were evaluable for toxicity which was mild in both groups; gastrointestinal disturbances were the most common. There were no treatment-related deaths. Grade 3-4 toxicity was uncommon in both arms. CONCLUSIONS: The addition of CPT-11 to the hybrid LV5FU2 regimen provided a significant overall response rate (40%) with relatively mild toxicity. The overall response rate was 18% in patients treated with LV5FU2 alone in the calibration arm. Thus, considering other encouraging data from the literature, the CPT-11 + FU-LV combination therapy can be regarded as a new, very effective treatment option for first-line treatment of advanced colorectal cancer patients.

Adult↗

Identification of bovine IgG as a major cross-reactive vertebrate meat allergen.

BACKGROUND: Although beef is a main source of protein in Western diets, very little has been published on allergic reactions to beef or the main allergens implicated in these reactions. The aim was to evaluate the IgE antibody response to beef in suspected meat-allergic subjects and assess cross-reactivity of beef with other vertebrate meats. METHODS: Fifty-seven sera from suspected meat-allergic subjects were tested by grid blot for specific IgE antibodies to vertebrate meats (beef, lamb, pork, venison, and chicken), and the patterns of recognition of meat proteins were assessed by immunoblot studies. RESULTS: A 160-kDa band, identified as bovine IgG, was detected in raw beef in 83% (10/12) of beef-allergic subjects but in only 24% of the beef-tolerant subjects. IgE reactivity to a band of similar mol. mass was detected also in lamb and venison, but rarely in pork or chicken. Complete inhibition of the IgE reactivity to the bovine IgG was obtained with lamb, venison, and milk. IgE reactivity to this band also completely disappeared when beef or lamb extracts were separated under reducing conditions, indicating conformational epitopes. CONCLUSIONS: Bovine IgG appears to be a major cross-reacting meat allergen that could predict beef allergy. Further studies with oral IgG challenges should be performed to document the conclusion that in vitro reactivity correlates with clinical hypersensitivity. The role of bovine IgG in other bovine products such as milk, dander, or hair must also be studied, and the hypothesis that it is a cross-reacting allergen with other mammalian products validated.

Adolescent↗

Ex vivo expansion of CD34-positive peripheral blood progenitor cells from patients with non-Hodgkin's lymphoma: no evidence of concomitant expansion of contaminating bcl2/JH-positive lymphoma cells.

The aim of the present study was to evaluate the capacity to expand of hematopoietic stem cell (HSC) samples from eight patients with NHL, and to follow in parallel the fate of tumor cells in four of eight samples still containing bcl2/JH+ tumor cells after CD34+ or CD19-/20-/34+ cell selection. The presence of bcl2/JH+ cells was also investigated after expansion in four of eight samples, two of which were bcl2/JH at harvesting and two which were initially bcl2/JH+ but became bcl2/JH (below the level of PCR detection) after cell selection, to assess a possible reappearance of occult tumor cells after expansion culture. We used culture conditions that we previously had established to allow high level expansion of normal precursors, progenitors and LTC-ICs. In this study, particular attention was given to the role of Flt3-ligand, known to favor the growth of B cells. The expansion conditions were: 1.5 x 10(3) cells/ml in serum-free medium containing stem cell factor (SCF), interleukin-3 (IL-3), IL-6, granulocyte-stimulating factor (G-CSF), erythropoietin (Epo) +/- Flt3-ligand (Flt3-L) for 10 days. After culture, total cells, CFU-GMs, BFU-Es and LTC-ICs were expanded to a mean of 833-, 6.6-, 4.6-, and 1.8-fold, respectively with the cocktail of cytokines not including Flt3-L. When Flt3-L was added, the mean expansion values were 1095-, 31-, 15- and three-fold, respectively. Residual bcl2/JH+ cells present in four of eight samples before expansion were not detected after expansion. Similarly, no tumor cells reappeared after expansion of the two samples which had become negative after selection, as well as in the two samples which were bcl2/JH- at harvesting. These results suggest first that ex vivo expansion of hematopoietic stem cells in patients with non-Hodgkin's lymphoma is feasible without incurring the parallel risk of amplifying tumor cells; second, that Flt3-L did not stimulate the growth of tumor cells while it clearly favored the growth of normal progenitors.

Adult↗