Biomedical subjects

J C Marini

Publications and source records attributed to J C Marini.

At least 55 records · Page 3Linked to original sources

PubMed1994

A rationally designed CD4 analogue inhibits experimental allergic encephalomyelitis.

Experimental allergic encephalomyelitis (EAE) is an acute inflammatory autoimmune disease of the central nervous system that can be elicited in rodents and is the major animal model for the study of multiple sclerosis (MS). The pathogenesis of both EAE and MS directly involves the CD4+ helper T-cell subset. Anti-CD4 monoclonal antibodies inhibit the development of EAE in rodents, and are currently being used in human clinical trials for MS. We report here that similar therapeutic effects can be achieved in mice using a small (rationally designed) synthetic analogue of the CD4 protein surface. It greatly inhibits both clinical incidence and severity of EAE with a single injection, but does so without depletion of the CD4+ subset and without the inherent immunogenicity of antibody. Furthermore, this analogue is capable of exerting its effects on disease even after the onset of symptoms.

Amino Acid Sequence↗

PubMed1993

Two additional cases of osteogenesis imperfecta with substitutions for glycine in the alpha 2(I) collagen chain. A regional model relating mutation location with phenotype.

The relationship between the clinical severity of osteogenesis imperfecta (OI) and the location and type of amino acid substitution in type I collagen is not identical for mutations in the alpha 1(I) and alpha 2(I) chains. Furthermore, the alpha 2(I) chain, once thought to be associated with moderate forms of OI, has now been associated with approximately as many lethal as non-lethal cases. We describe two novel substitutions for glycine in the alpha 2(I) chain, one associated with a lethal phenotype in twins and the other with a moderate non-lethal phenotype. The type I collagen of all probands was characterized electrophoretically by two populations of alpha chains, one normal and one with delayed migration. Cyanogen bromide peptides of the overmodified alpha 1(I) chains revealed delayed migration of all peptides except CB6. The indicated target region of alpha 1(I) and alpha 2(I) cDNA of the probands was analyzed by RNA-DNA hybrid analysis with RNase A digestion. All probands had mismatches in the region of alpha 2(I) coding for amino acids 642-912. The lethal phenotype was associated with a G-->A mutation, resulting in Gly706-->serine; the non-lethal mutation was a G-->T change resulting in Gly676-->valine. Both mutations occurred de novo in the probands; parental leukocyte DNA was normal. In conjunction with the previously described exon deletions and point mutations in alpha 2(I), these mutations define five alternating non-lethal/lethal regions along the chain and support a regional, as opposed to a gradient, model of OI pathophysiology. These mutations in particular help to define a lethal/non-lethal junction at about alpha 2(I) amino acid 700.

Amino Acid Sequence↗

PubMed1993

Serine for glycine substitutions in type I collagen in two cases of type IV osteogenesis imperfecta (OI). Additional evidence for a regional model of OI pathophysiology.

Serine for glycine substitutions in type I collagen have been described in seven cases of lethal type II osteogenesis imperfecta (OI), and six cases of nonlethal OI. We describe here two cases of moderately severe type IV OI with serine substitutions at alpha 1(I) Gly352 and alpha 2(I) Gly922, respectively. In both cases, G-->A point mutations were detected by RNase A cleavage of RNA/RNA and RNA/DNA hybrids. These cases extend the location for serine substitutions producing the moderately severe OI phenotype to the alpha 2(I) chain and the amino-terminal end of the alpha 1(I) chain. Their location supports a regional model of OI pathophysiology for serine substitutions. The proband with alpha 2(I) Gly922-->Ser has both normal and overmodified forms of both type I collagen chains. The overmodified form has delayed migration of all CNBr peptides. Helix thermal stability is decreased 4 degrees C. The fibroblast collagen protein and RNA of her unaffected parents are normal. However, the father was demonstrated to be a mosaic carrier using leukocyte DNA. The fibroblasts of the proband whose serine substitution is at alpha 1(I) Gly352 synthesize type I procollagen chains with delayed electrophoretic migration; normally migrating forms are difficult to detect. Only alpha 1(I) CB 8 displayed delayed migration. Helix thermal stability is reduced 2 degrees C. Parental genomic DNA was normal.

Amino Acid Sequence↗

PubMed1993

Moderately severe osteogenesis imperfecta associated with substitutions of serine for glycine in the alpha 1(I) chain of type I collagen.

We have examined the type I collagen protein, RNA, and cDNA of 2 children with moderately severe (type IV) osteogenesis imperfecta (OI). They have in common a non-lethal form of OI with ambulatory potential, overmodification of type I collagen protein, and a substitution of serine for glycine in the collagen chain produced by one alpha 1(I) allele. The first child (Marini et al.: J Biol Chem 264:11893-11900, 1989) is now 7 years old, with the height of a 3-year-old. Her course includes significant remodeling of lower long bones and 4 femur fractures. She walks independently. A mishmatch was detected in her alpha 1(I) mRNA using RNA/RNA hybrids; it was demonstrated to be due to a G-->A point mutation in one allele of alpha 1(I), resulting in the substitution of serine for glycine 832. The second child is now 6 1/2 years old, with the height of 1 1/2-year-old. Her history includes significant bowing of femurs and tibias, 6 femur fractures, S-curve scoliosis, compression of all lumbar vertebrae, and limited short-distance walking with braces. Her alpha 1(I) mRNA has also been studied by RNA hybrid analysis; there is a single G-->A change in one alpha 1(I) allele causing the substitution of serine for gly 352. Both children have moderately severe OI. However, the serine substitution at gly 352 is associated with a more severe phenotype then is the serine substitution at gly 832. Compared to substitutions described in other cases of OI, the serine 352 is located in the middle of a cluster of cysteine substitutions associated with non-lethal OI.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗

PubMed1993

Evaluation of growth hormone axis and responsiveness to growth stimulation of short children with osteogenesis imperfecta.

Growth deficiency is a cardinal manifestation of severe Osteogenesis Imperfecta (OI) and occurs frequently in moderate to mild OI. We have investigated the status of the hormones related to growth in 28 children with OI. Our goals were to determine whether there were any abnormalities of these hormones, whether the abnormalities correlated with types of OI, and whether OI bone could be safely stimulated to grow. The study group included 14 females and 14 males. Using the criteria developed by Sillence et al. [1979], 13 children had OI type III, 12 had OI type IV, and 3 had OI type I. Evaluation included 3 standard hGH provocative tests (AITT, L-Dopa), GRF stimulation, 24 hr q20 minute sampling of unstimulated growth hormone, and a somatomedin generation test. All patients except one had normal responses to standard provocative stimuli. Responses to GRF fell into 2 groups: one with a mean response similar to that of normal children, and one with a mean response resembling that of GH deficient children. The group with low response to GRF had a significantly lower area under the curve in the 24-hr test of unstimulated GH than did the normal response group. The OI children as a group showed a blunted IGF-1 response during the Somatomedin Generation Test, with 18/28 children having less than a two-fold stimulation. No test results correlated with OI type. Ten OI children were enrolled in a pilot growth stimulation study. Two children received protropin and 8 received clonidine for at least 6 months. Both children treated with protropin and 4/8 treated with clonidine experienced at least a doubling of their pre-treatment growth rates. Lack of growth hormone response did not correlate with type of OI or parameters from the hormonal evaluation. We speculate that there is a group of OI children who have a hypoactive growth hormone axis. Some OI bone appears to respond to GH and a treatment trial with protropin is planned for a larger number of children.

Body Height↗

PubMed1993

A de novo G+1-->A mutation at the alpha 2(I) exon 16 splice donor site causes skipping of exon 16 in the cDNA of one allele of an OI type IV proband.

We have investigated the procollagen, collagen, alpha 2(I) mRNA, and DNA of a proband with type IV OI. The proband synthesized two alpha 2(I) chains, one with normal electrophoretic migration and one more rapidly migrating. The fast alpha 2(I) chain was relatively retained within the cell and was present in collagens synthesized in the presence of alpha,alpha'-dipyridyl. The alpha 2(I) cyanogen bromide peptide CB 4-2 contained both normal and rapidly migrating components. Thermal stability of helices containing the rapidly migrating alpha 2(I) chain was reduced 6 degrees C. Parental fibroblast collagens were normal. RNA/RNA hybrids between proband total RNA and antisense riboprobe complementary to alpha 2(I) nt 236-1390 were digested with RNase A and T1. Digestion products seen exclusively in the proband suggested a structural change in the region coding for exons 16-19. The region which hybridized to the riboprobe was amplified using RNA-PCR and subcloned. Multiple restriction enzyme digestions of the two subcloned alleles suggested a structural change localized to the region coding for exons 16-17. Sequencing revealed a deletion of the 54 bp comprising exon 16 in the cDNA of one allele. The region of the proband's genomic DNA spanning exons 15-17 was amplified by PCR. The subcloned genomic fragments of each allele were distinguished by RNA/DNA hybrid analysis using a riboprobe complementary to normal genomic DNA from this region. Sequencing revealed a G+1-->A mutation at the exon 16 donor site in one allele. The mutation eliminates a StyI site.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗

PubMed1993

The pituitary hormones arginine vasopressin-neurophysin II and oxytocin-neurophysin I show close linkage with interleukin-1 on mouse chromosome 2.

Arginine vasopressin (AVP) and oxytocin (OXT) are posterior pituitary hormones. AVP is involved in fluid homeostasis, while OXT is involved in lactation and parturition. AVP is derived from a larger precursor, pre-pro-arginine-vasopressin-neurophysin II (prepro-AVP-NP II; AVP), and is physically linked to prepro-oxytocin-neurophysin I (prepro-OXT-NP I; OXT). The genes for AVP and OXT are separated by only 12 kb of DNA in humans, whereas in the mouse 3.5 kb of intergenic sequence lies between Avp and Oxt. Interspecific backcross analysis has now been used to map the Avp/Oxt complex to chromosome 2 in the mouse. This map position confirms and extends the known region of linkage conservation between mouse chromosome 2 and human chromosome 20.

Animals↗

PubMed1993

Ophthalmologic examination in the diagnosis of Proteus syndrome.

PURPOSE: To describe the clinical features of Proteus syndrome, a rare recently recognized hamartoneoplastic malformation, with emphasis on the ocular findings. METHODS: Complete physical and ocular examination of two new patients with Proteus syndrome. RESULTS: The two reported cases illustrate the wide clinical polymorphism of Proteus syndrome and the overlap of its clinical manifestations with those of other overgrowth syndromes. Both patients had periorbital exostoses and epibulbar tumors. The ocular findings are compared with those in the literature. CONCLUSION: Considering the paucity of information in the ophthalmic literature, this article explores the role of the ophthalmologist in diagnosing this rare entity.

Abnormalities, Multiple↗

PubMed1993

The growth hormone and somatomedin axis in short children with osteogenesis imperfecta.

Growth deficiency is a cardinal feature of severe osteogenesis imperfecta (OI) and a frequent feature of mild to moderate forms of this disease. We have investigated the status of hormones related to growth in 22 short prepubertal children, 13 males and 9 females, with various types of OI. Ten children had Sillence type III OI, 10 had type IV, and 2 had type I. Evaluation included GRH stimulation, three standard GH provocative tests (arginine-insulin tolerance test, L-dopa), 24-h sampling for measurement of unstimulated GH secretion and a somatomedin-C generation test. None of these children had GH deficiency by standard criteria. We found that 9 OI children had decreased responsiveness to GRH, similar to the GRH response of GH-deficient children. Overall, however, mean 24-h GH values and mean peak GH response to provocative agents of OI children were within the normal range. In the somatomedin generation test, the OI children as a group showed a blunted response, with 13 of 22 having less than a 2-fold stimulation of somatomedin-C by GH. This suggested resistance of the liver and other somatomedin-C secreting tissues to GH. The group with blunted insulin-like growth factor-I response did not correlate significantly with the group with decreased GRH response. To investigate the responsiveness of OI bone to growth stimulation, six OI children with less than average integrated GH secretion were enrolled in a pilot study in which one child received exogenous GH and six received clonidine for at least 6 months. The child treated with exogenous GH and three of six treated with clonidine experienced at least a 4.7 cm/yr increase over their pretreatment growth rates. Growth response could not be predicted from baseline studies. We conclude that abnormalities of the GH-somatomedin axis exist in some children with OI. Administration of GH or clonidine may augment growth rates in OI children; however, the effect of these agents on final stature is unknown.

Adolescent↗

PubMed1993

Communicating hydrocephalus, basilar invagination, and other neurologic features in osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is anecdotally associated with macrocephaly, hydrocephalus, basilar invagination, and cerebral atrophy, but the frequency and the spectrum of neurologic features of this condition are poorly defined. We report our experience with 76 patients with OI seen at NIH. Neuroimaging studies demonstrated sulcal prominence and ventriculomegaly consistent with communicating hydrocephalus in 17 patients. Eight individuals with severe OI types displayed basilar invagination, causing brainstem compression in three patients. Head circumference growth showed abnormal kinetics with percentile crossing after fontanelle closure in 13 patients, and absolute macrocephaly was present in 11 patients. Additional neurologic complications included skull fracture (10 individuals); seizure disorders (five); transient, unexplained long tract signs (three); and spinal compression and pontine, cervical, and thoracic syringohydromyelia (one patient each). The clinically important neurologic complications appear to be brainstem compression from basilar invagination, skull fracture, and seizure disorders. Neurologic evaluation should be part of a team approach in the management of patients with severe OI types.

Adolescent↗

PubMed1992

New autosomal recessive syndrome of sparse hair, osteopenia, and mental retardation in Mennonite sisters.

We report on 2 Mennonite sisters with a syndrome of sparse hair, osteopenia, mental retardation, minor facial abnormalities, joint laxity, and hypotonia. Their asymptomatic consanguineous parents (inbreeding coefficient F = 1/64) have 6 other offspring, 3 of whom died in infancy of type II osteogenesis imperfecta (OI), and 3 of whom are normal. We analyzed collagens synthesized by cultured fibroblasts from these 2 sisters and their parents and detected no major abnormalities. Results of chromosomal and metabolic evaluations including amino acid analysis of plasma, urine, and hair were unremarkable. A literature search and survey of a computerized syndrome identification database did not disclose an identical phenotype. The sisters bear superficial resemblance to several known syndromes which we excluded on clinical and/or biochemical grounds. We conclude that they represent a new autosomal recessive syndrome, distinct from type II OI and perhaps unique to the Mennonite population or to this particular family.

Bone Diseases, Metabolic↗

PubMed1992

Autoimmune inflammation of astrocyte transplants.

Astrocytes have been shown to be capable of serving as antigen-presenting cells and as targets for encephalitogenic cytotoxic T lymphocytes. The role of astrocytes in central nervous system (CNS) autoimmune inflammation is unclear. To study this further, we transplanted astrocyte aggregates into the anterior eye chamber of the mouse. The astrocytic nature of these transplants was confirmed by immunohistochemical detection of glial fibrillary acidic protein and the inability to detect oligodendrocyte or microglial markers. When mice bearing transplants were induced to develop experimental allergic encephalomyelitis by either passive or active protocols, the astrocyte transplants developed a perivascular inflammatory response similar to that seen in the host CNS during the course of the encephalomyelitis. The data suggest that astrocytes could serve as targets for the autoimmune attack of experimental allergic encephalomyelitis and support the possibility that the pathogenesis of this disease may involve an autoimmune reaction against a site other than the myelin sheath.

Animals↗

PubMed1992

Distribution of the blood-brain barrier in heterotopic brain transplants and its relationship to the lesions of EAE.

The blood-brain barrier (BBB) is recognized as a barrier to the trafficking of molecules and cellular elements into the central nervous system (CNS). Horseradish peroxidase (HRP) exclusion is used as a measure of BBB integrity. The BBB is altered and becomes permeable during the course of experimental allergic encephalomyelitis (EAE). Heterotopic brain transplantation into the anterior eye chamber is a technique for studying genetic influences and the role of individual cell types on the development of EAE. Prior to EAE induction, HRP is excluded from the central portion of the transplant, demonstrating an intact BBB. In contrast, HRP localization is found at the periphery of the transplant, suggesting an incomplete barrier. However, EAE lesions typically occur within the more central regions of the transplant, where the BBB is intact, and not at peripherally located "leaky" areas. This suggests that endothelial cells at intact BBB sites may direct trafficking of lymphocytes (gating) into the CNS during the development of EAE, rather than the passive entry of lymphocytes into the CNS through a leaky BBB.

Animals↗

PubMed1991

Intractable vasculitis, resorptive osteolysis, and immunity to type I collagen in type VIII Ehlers-Danlos syndrome.

A unique patient with type VIII Ehlers-Danlos syndrome and cutaneous vasculitis, resorptive osteolysis, and cardiac valvular disease is described. Collagen analyses identified morphologic and physical abnormalities of type I collagen. The patient's T lymphocytes could be propagated in vitro with type I collagen and produced a 60-kd lymphokine that bound this protein. Cellular autoimmunity to type I collagen may be responsible for this patient's intractable clinical condition.

Autoimmunity↗

PubMed1990

Detection of point mutations in type I collagen by RNase digestion of RNA/RNA hybrids.

We have developed a strategy for the detection, localization and sequence determination of point mutations in the mRNA coding for the alpha 1(I) and alpha 2(I) chains of type I collagen. Point mutations are detected by RNase A cleavage of mismatches in RNA/RNA hybrids. The mRNAs coding for the fibrillar collagens present special problems for hybrid analysis because of their large size and their GC-rich and repetitive sequences. We have generated a series of overlapping antisense riboprobes covering the entire pro alpha 1(I) and pro alpha 2(I) mRNAs. Uniformly labelled normal antisense riboprobes are hybridized with the total fibroblast RNA of patients with possible mutations in type I collagen. Mismatches in the resulting RNA/RNA hybrids are cleaved with RNase A and the labelled riboprobe cleavage products are examined electrophoretically. The sensitivity and specificity of the system were demonstrated by the detection and localization of a known point mutation in the codon for alpha 1(I) glycine 988 (1). DNA for sequencing the mutations localized by hybrid analysis may be obtained by either (1) generation of a fibroblast cDNA library and isolation of both alleles by plaque screening, or (2) a more rapid method using first strand cDNA synthesis from poly (A+)-mRNA, followed by PCR amplification of the mutation-containing region of the DNA/RNA hybrid. This strategy for detection and isolation has wide application not only for mutations causing connective tissue disorders, but also for mutations in other large and repetitive genes. We have used this strategy for the detection and sequencing of a point mutation in alpha 2(I) mRNA associated with a case of lethal osteogenesis imperfecta. The G----A point mutation in the codon for alpha 2(I) glycine residue 805 results in the substitution of an aspartic acid at this position and is consistent with the proband's collagen protein data.

Alleles↗

PubMed1990

Analysis of cultured chorionic villi in a case of osteogenesis imperfecta type II: implications for prenatal diagnosis.

We examined collagens produced by cultured cells from skin, chorionic villi, and placental membranes of a 32 week fetus with osteogenesis imperfecta (OI) type II. We observed that skin fibroblasts synthesized two populations of pro alpha 1(I) chains of type I procollagen; one population was normal, while the other population had excessive post-translational modification. The thermal stability of helices containing the overmodified chains was reduced 1-2 degrees C. Most significantly, the cells cultured from chorionic villi produced type I collagen chains with the same electrophoretic abnormalities as the skin collagen. This suggests that chorionic villus sampling (CVS) is a means of prenatal diagnosis for families with a previous type II or type IV OI infant.

Cells, Cultured↗

PubMed1990

Failure of surgery and isotretinoin to relieve jaw immobilization in fibrodysplasia ossificans progressiva: report of two cases.

Two patients with fibrodysplasia ossificans progressiva who presented with jaw immobilization due to formation of bone between the maxilla and mandible were treated with surgical resection of their ectopic bone in conjunction with experimental, adjunctive medical therapy using isotretinoin. Both patients had recurrence of their ectopic ossification within 2 months of surgery. Surgery to remove joint-bridging ossifications in FOP is not recommended.

Adolescent↗

PubMed1989

Osteogenesis imperfecta type IV. Detection of a point mutation in one alpha 1(I) collagen allele (COL1A1) by RNA/RNA hybrid analysis.

We have identified a point mutation in one alpha 1(I) collagen allele (COL1A1) of a child with the type IV osteogenesis imperfecta phenotype. When compared to parental and control samples, skin fibroblasts of the proband synthesized two populations of type I collagen molecules. One population was normal; the other was delayed in secretion and electrophoretic migration due to post-translational overmodification. Two-dimensional gel electrophoresis of the CNBr peptides demonstrated a gradient of overmodification beginning near the carboxyl-terminal CB peptides. This predicts that the mutation delaying helix formation is near the carboxyl-terminal end of one of the component chains of type I collagen. The mRNA of the patient was probed with overlapping antisense riboprobes to type I collagen cDNA. Cleavage of a mismatch in RNA/RNA hybrids of RNase A allowed the location of the mutation to a 225-base pair region of alpha 1(I) cDNA. The mismatch was not present in RNA/RNA hybrids from either parent. This region of both alpha 1(I) alleles of the patient was isolated by screening a lambda ZAP cDNA library. Sequence determination of both alleles demonstrated a single nucleotide change, G----A, resulting in the substitution of a serine for a glycine at amino acid residue 832. This point mutation occurs in the coding region for alpha 1(I) CB6 and is concordant with the protein data. The finding of a glycine substitution in an alpha 1(I) chain of a patient with the milder type IV osteogenesis imperfecta phenotype requires modification of current molecular models for types II and IV osteogenesis imperfecta.

Alleles↗