The prediction of serum IgG levels by scanning densitometry

A novel approach has been described. In this method the serum IgG level can be predicted with a fair degree of accuracy by scanning densitometry and total serum protein values. This approach might be useful as a screening procedure for hypogammaglobulinemia.

Calcium regulation of growth and differentiation of normal human keratinocytes: modulation of differentiation competence by stages of growth and extracellular calcium

In this study we examined the different aspects of the pathway leading to the differentiation of keratinocytes as a function of time in culture and calcium concentration of the culture medium. Human neonatal foreskin keratinocytes were grown in a serum-free, defined medium containing 0.07, 1.2, or 2.4 mM calcium and assayed for the rate of growth and protein synthesis, involucrin content, transglutaminase activity, and cornified envelope formation at preconfluent, confluent, and postconfluent stages of growth. We observed that keratinocytes grown to postconfluence in all calcium concentrations showed an increased protein/DNA ratio and an increased rate of membrane-associated protein synthesis. Extracellular calcium concentrations did not have a clear influence on these parameters. However, preconfluent and confluent keratinocytes grown in 0.07 mM calcium showed markedly retarded differentiation at all steps, i.e., involucrin synthesis, transglutaminase activity, and cornified envelope formation. Within 1 week after achieving confluence, these keratinocytes began synthesizing involucrin and transglutaminase and developed the ability to form cornified envelopes. Cells grown in 1.2 and 2.4 mM calcium synthesized involucrin and transglutaminase prior to confluence and were fully competent to form cornified envelopes by confluence. Thus external calcium-regulated keratinocyte differentiation is not an all or none phenomenon, but rather it is the rate at which keratinocytes differentiate that is controlled by calcium. We conclude that either or both higher extracellular calcium concentration and the achievement of cell-cell contacts lead to a coordinate increase of at least two precursors--involucrin content and transglutaminase activity--required for cornified envelope formation. We speculate that a critical level of cytosolic calcium, achieved by increased extracellular calcium or by achievement of intercellular communication established by cell-cell contact, may trigger mechanisms required for initiation of keratinocyte differentiation.

The Mac-2 antigen is a galactose-specific lectin that binds IgE

A cDNA encoding the Mac-2 antigen, a surface marker highly expressed by thioglycollate-elicited macrophages, has been cloned by immunoscreening of a lambda gt11-P388D1 expression library. The nucleotide sequence of the cDNA is identical to that of carbohydrate-binding protein 35, a galactose-specific lectin found in fibroblasts and highly homologous to a rat IgE-binding protein from basophilic leukemia cells. The in vitro synthesized Mac-2 protein displayed the expected carbohydrate- and IgE-binding properties. By pulse-chase analysis and subcellular fractionation studies, the Mac-2 protein was found in the cytosol but was also seen to accumulate in the extracellular medium. The latter finding was surprising in view of the fact that the cDNA did not encode a signal peptide or transmembrane domain. An alternatively spliced cDNA with the potential to encode a NH2 terminally extended Mac-2 protein with a stretch of hydrophobic amino acids at its NH2 terminus was also found, but it is not clear whether it is the source of the extracellular Mac-2. Possible functions for the Mac-2 protein based on its lectin- and IgE-binding properties are discussed.

Herpes zoster ophthalmicus, contralateral hemiplegia, and recurrent ocular toxoplasmosis in a patient with acquired immune deficiency syndrome-related complex

A 42-year-old man presented with herpes zoster ophthalmicus on the right side. He was found to have acquired immune deficiency syndrome-related complex. Two weeks later he developed toxoplasmic retinochoroiditis in the left eye. He also presented later with left hemiplegia, which was probably caused by herpes zoster arteritis. Nine months after the retinal lesion resolved he developed another area of toxoplasmic retinochoroiditis adjacent to the first lesion. Herpes zoster may be the first presentation of acquired immune deficiency syndrome-related complex in a young healthy individual. Ophthalmologists are encountering patients with acquired immune deficiency syndrome who may have multiple organisms as the cause for their ocular infections and this might pose a treatment dilemma. The combination of herpes zoster ophthalmicus and ocular toxoplasmosis in this patient makes this case unusual.

Nondysenteric intestinal amebiasis. Colonic morphology and search for Entamoeba histolytica adherence and invasion

There is controversy regarding the presence of colonic mucosal abnormalities or mucosal invasion by Entamoeba histolytica in patients with "nondysenteric intestinal amebiasis." To determine the role of E. histolytica in causing symptoms and mucosal changes and to detect if mucosal invasion by E. histolytica is present in nondynsenteric intestinal amebiasis, we evaluated 24 E. histolytica-infected patients (stool microscopy positive for E. histolytica) and 12 noninfected controls who presented with chronic gastrointestinal symptoms, but without dysentery, to a clinic in Calcutta. The colonic mucosa was evaluated at colonoscopy, and mucosal biopsies obtained from the cecum, sigmoid colon, and rectum were evaluated by light microscopy, indirect immunofluorescence microscopy, and scanning electron microscopy. At colonoscopy mucosal ulcerations were absent in all the controls and all except one of the E. histolytica-infected patients. E. histolytica trophozoites or cysts were not seen in the lamina propria or on the luminal surface in any infected patient by light and immunofluorescence microscopy. On scanning electron microscopy, structures that resembled rounded E. histolytica trophozoites were seen on the luminal surface in two of 19 cecal specimens from the infected patients. Moderate or severe mucosal inflammation was frequent on light microscopy in both the E. histolytica-infected patients and the noninfected controls with the cecum involved in two thirds of both groups. Antibodies to E. histolytica were detected in serum of 25% of study patients and 58% of controls. Mucosal inflammation did not correlate with stool positivity for E. histolytica or seropositivity for ameba antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding and biological effects of tumor necrosis factor alpha on cultured human neonatal foreskin keratinocytes

Tumor necrosis factor alpha (TNF alpha) localizes to the epidermis when injected in vivo, but its role in the skin has heretofore not been evaluated. As a first approach to assessing the role of TNF alpha in the skin, we evaluated the binding and biological effects of TNF alpha on human neonatal foreskin keratinocytes maintained in culture. We found that TNF alpha at 0.3-1.0 nM inhibited proliferation of keratinocytes in a reversible fashion as demonstrated by a reduction in total DNA content and clonal growth. The antiproliferative effects were most marked when TNF alpha was added in the preconfluent stages of cell growth. Accompanying this antiproliferative effect was a stimulation by TNF alpha of differentiation of keratinocytes as indicated by the stimulation of cornified envelope formation. Keratinocytes specifically bound TNF alpha, reaching maximal binding in 2 h at 34 degrees C or 8 h at 4 degrees C. Much of the apparent binding at 34 degrees C was due to internalization of the TNF alpha. At 4 degrees C the rate of internalization was much less. Confluent keratinocytes showed a single class of high-affinity receptors with 1,250 receptors/cell and a Kd of 0.28 nM. These data suggest a role for TNF alpha in the growth and differentiation of the epidermis.

Regulation of 1,25-dihydroxyvitamin D production in human keratinocytes by interferon-gamma

Interferon-gamma (IFN gamma) and 1,25-dihydroxyvitamin D [1,25-(OH)2D] each have potent antiproliferative and prodifferentiating effects on keratinocytes. Since keratinocytes produce 1,25-(OH)2D, we explored the possibility that IFN gamma acted on keratinocytes in part by regulating 1,25-(OH)2D production. We cultured human neonatal foreskin keratinocytes for various periods of time in the presence of various concentrations of IFN gamma before assessing their ability to produce 1,25-(OH)2D. The production of 1,25-(OH)2D by preconfluent keratinocytes grown in the presence of serum (which retards differentiation) was stimulated by 1.8 nM IFN gamma. Postconfluent keratinocytes did not respond to 1.8 nM IFN gamma. The production of 1,25-(OH)2D by keratinocytes grown in serum-free medium was maximally stimulated by 0.006 nM IFN gamma and inhibited at concentrations greater than 0.06 nM. Keratinocytes grown in 0.1 mM calcium serum-free medium (which prevents differentiation) were more sensitive to both the stimulatory and inhibitory effects of IFN gamma than keratinocytes grown in 1.2 mM calcium serum-free medium (which permits differentiation). The stimulatory effect of IFN gamma on 1,25-(OH)2D production was maximal after 2 days of incubation. Incubations longer than 2 days showed increasingly less stimulation at the low IFN gamma concentrations and increasingly greater inhibition at the higher IFN gamma concentrations. The inhibitory effects of IFN gamma on 1,25-(OH)2D production paralleled the inhibitory effects of IFN gamma on cell growth. Thus, IFN gamma does regulate 1,25-(OH)2D production by keratinocytes. However, this regulation is modulated by the state of keratinocyte proliferation and differentiation and is influenced by calcium and undefined factors in serum. The data are consistent with the possibility that IFN gamma alters keratinocyte differentiation in part by regulating 1,25-(OH)2D production.

Synthetic peptide representing a T-cell epitope of CRM197 substitutes as carrier molecule in a Haemophilus influenzae type B (Hib) conjugate vaccine

The cross-reactive material (CRM197) of diphtheria toxin is considered to be advantageous as a carrier molecule in the formulation of a Haemophilus influenzae type b conjugate vaccine. In order to more precisely understand the function of the CRM197 in the vaccine, we have begun mapping the T-cell epitopes of the protein. A peptide which represents a segment of the primary sequence of CRM197 has been identified and found to stimulate diphtheria toxoid or CRM197-primed murine T-lymphocytes. In addition, the peptide is capable of priming T-cells in vivo for a subsequent in vitro T-cell response to itself or to the intact CRM197 molecule. The ability of the peptide to replace CRM197 as a carrier molecule was examined by immunizing mice with PRP, PRP-CRM197 conjugate, or PRP covalently coupled to the peptide. Antibodies to PRP were only detected in the PRP-CRM197 or PRP-peptide immunized groups. Both conjugates elicited primary and secondary antibody responses. Thus, a synthetic peptide representing a defined T-cell epitope of CRM197 has been functionally demonstrated based on its ability to act as a carrier molecule in a PRP conjugate vaccine.

Transient lenticular opacification following trabeculectomy

Permanent lens changes may occur following filtering procedures for glaucoma, most often within a few years after the surgery. We present a case in which transient lenticular opacification occurred two days after trabeculectomy without intraoperative injury to the lens. The patient regained her preoperative vision 2 weeks postoperatively. We postulate that such reversible lenticular opacities may be due to changes in lens metabolism associated with hypotony.

Relationship of steroid dose to degree of posterior subcapsular cataracts in nephrotic syndrome

Forty-five patients with nephrotic syndrome were included in our study. Of these, 30 received adrenocorticosteroid therapy and 15 did not. The ages of the patients ranged from 11 months to 27 years and the duration of steroid therapy from 2 1/2 years to 20 years. Seventeen patients (38%) showed posterior subcapsular cataract (PSC) formation and, of these, seven patients (41%) showed reversal of PSC. There was no statistical correlation between the total dose of steroids and the degree of PSC. An individual susceptibility may be an important factor in the production of PSC. None of the patients had visual acuity less than 20/30.

1,25-Dihydroxyvitamin D production and receptor binding in human keratinocytes varies with differentiation

Human foreskin keratinocytes in culture produce 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) and 24,25-dihydroxycholecalciferol (24,25-(OH)2D3) from 25-hydroxycholecalciferol (25-(OH)D3). The production of 1,25-(OH)2D3 by these cells correlated with the early events of differentiation such as expression of transglutaminase activity and the levels of a precursor protein for the cornified envelopes, involucrin. In contrast, the increased production of 24,25-(OH)2D3, as 1,25-(OH)2D3 production declined, correlated with the terminal differentiation marker, cornified envelope formation. Exogenous 1,25-(OH)2D3 (10(-11)-10(-9) M) inhibited the 1-alpha-hydroxylase at all stages of growth of these cells. Keratinocytes in culture expressed receptors for 1,25-(OH)2D3 which had similar sedimentation behavior in sucrose density gradients as chick intestinal cytosol receptors. Cells in early stages of growth (preconfluent and confluent) contained higher numbers of receptors (26-27 fmol/mg protein) than post-confluent cells. The dissociation constant (237-278 pM) of these receptors for 1,25-(OH)2D3 was not consistently altered by differentiation. Since 1,25-(OH)2D3 is a potent stimulator of cell differentiation in a variety of systems including the epidermis, our results suggest the possibility that endogenous 1,25-(OH)2D3 production may participate in the differentiation of keratinocytes in culture and, perhaps, in vivo.

Biochemical and morphological characterization of growth and differentiation of normal human neonatal keratinocytes in a serum-free medium

Growth and differentiation of keratinocytes in a serum-free medium (keratinocyte growth medium or KGM) was studied and compared to that under conditions in which serum and feeder cell layers were used. Cells were grown in KGM containing 0.1 mM calcium (KGM/low calcium), KGM containing 1.2 mM calcium (KGM/normal calcium), or Dulbecco's modified Eagles medium containing 5% fetal calf serum and 1.8 mM calcium in presence of mitomycin treated 3T3 M cells (DMEM/5% FCS). Plating efficiency and rate of growth were similar in the three media till confluence. In postconfluent cultures, protein and DNA content of cells attached to the plate in KGM/low-calcium dishes decreased as an increased number of cells were shed into the medium. Cell shedding was much less evident in the presence of normal calcium. Cells grown in KGM/low calcium had a higher rate of cell proliferation (3H-thymidine incorporation into cellular DNA) than cells grown in normal calcium. Transglutaminase activity, involucrin content, and cornified envelope formation were greatest in cells grown in KGM/normal calcium, intermediate in cells grown in DMEM/5% FCS, and least in cells grown in KGM/low calcium. Keratin profiles from cells grown in KGM/low calcium showed a lower percentage of high molecular weight bands compared to the keratin profiles from cells grown in the presence of normal calcium. Keratinocytes in KGM/low calcium grew as a monolayer of cuboidal cells with few features of differentiation, whereas cells grown in KGM/normal calcium stratified into multilayered islands (3-5 layers) surmounted by 2-4 layers of enucleated cells with thickened cornified envelopes. Cells grown in KGM/normal calcium also contained tonofilaments and lamellar bodies unlike cells grown in KGM/low calcium. Cells grown in DMEM/5% FCS also formed stratified layers comparable to cells grown in KGM/normal calcium but lacked cornified cells, keratohyalin granules, tonofilament bundles, and lamellar bodies. These studies indicate the usefulness of serum-free conditions for the culture of human keratinocytes and confirm the importance of extracellular calcium in keratinocyte differentiation.

Vitamin D and epidermal differentiation: evidence for a role of endogenously produced vitamin D metabolites in keratinocyte differentiation

Vitamin D3 is produced in the skin. It is metabolized primarily in the liver to the major circulating form 25-hydroxy vitamin D3, [25(OH)D3] which is metabolized in the kidney to produce the biologically active form of the hormone, 1,25-dihydroxy vitamin D3, [1,25(OH)2D3]. The skin not only participates in the production of vitamin D3 but also contains receptors for 1,25(OH)2D3 suggesting a role of this hormone in the growth and differentiation of this tissue. 1,25(OH)2D3 appears to play a role in epidermopoiesis and melanin pigmentation. Recently, using cultures of neonatal human foreskin keratinocytes, we have demonstrated that these cells produce abundant quantities of 1,25(OH)2D3 from 25(OH)D3. The production of 1,25(OH)2D3 varies with the degree of differentiation of keratinocytes and is regulated by exogenous 1,25(OH)2D3. 1,25(OH)2D3 induces differentiation possibly because of its ability to increase intracellular free calcium levels. A tentative model is provided to demonstrate potential mechanisms by which 1,25(OH)2D3-induced changes in intracellular calcium could regulate epidermal differentiation.

Myristoylation and the post-translational acquisition of hydrophobicity by the membrane immunoglobulin heavy-chain polypeptide in B lymphocytes

Membrane immunoglobulin heavy chain in pre-B and in B cells is initially synthesized as a relatively hydrophilic protein that is nonetheless stably anchored in the endoplasmic reticulum membrane. In B cells, but not in pre-B cells, the membrane immunoglobulin heavy chain is post-translationally converted to a relatively hydrophobic form that partitions into the oil phase when solubilized with the phase-separating detergent Triton X-114. Covalent myristoylation of the membrane and secretory forms of immunoglobulin heavy chains as well as of light chains was observed in B cells. Myristoylation of the membrane immunoglobulin heavy chain correlates with its transport to the cell surface and its post-translational conversion to a relatively hydrophobic form. This post-translational modification is hydroxylamine resistant and may be responsible for the assembly and transport of membrane immunoglobulin to the cell surface in B cells.

The effect of vitamin D status on cutaneous sterologenesis in vivo and in vitro

Recent studies have shown that cutaneous sterologenesis is autonomous from the influence of circulating sterols, and that the epidermis is an important site of sterologenesis which is regulated by permeability barrier requirements. In addition to barrier function, an additional, important function of the epidermis is to synthesize sterol precursors of vitamin D3. The present study was designed, first, to determine whether vitamin D status and/or circulating levels of 1,25-dihydroxyvitamin D3 might play a role in regulating cutaneous sterol synthesis in vivo and, second, whether 1,25-dihydroxyvitamin D3 modulates sterologenesis in cultured human keratinocytes. Hairless mice were maintained on a vitamin D-deficient diet in the dark and supplemented with various doses of vitamin D3/day. Despite demonstrating serum 25-hydroxyvitamin D3 levels ranging from less than 10 to 343 ng/ml, the incorporation of tritiated water into cholesterol and total nonsaponifiable lipids in both the epidermis and dermis was similar in the four groups of animals. Likewise, administration of various doses of 1,25-dihydroxyvitamin D3 to vitamin D-deficient mice resulted in serum levels of 1,25-dihydroxyvitamin D3 ranging from less than 10 to 85 pg/ml; yet, cholesterol and total nonsaponifiable lipid synthesis was similar in both the dermis and epidermis in all groups of animals. Moreover, administration of 0.6 micrograms/kg per day of 1,25-dihydroxyvitamin D3 to 'normal' vitamin D-replete mice also had no effect on cutaneous sterol synthesis. Furthermore, conversion of 7-dehydrocholesterol to cholesterol in vitamin D-deficient vs. supplemented animals did not differ. Finally, addition of 1,25-dihydroxyvitamin D3 to cultured keratinocytes over a concentration range of 10(-12)-10(-7) M did not affect sterologenesis, except at supraphysiologic doses (10(-7) M). Together, these results suggest that vitamin D status does not influence sterol synthesis in the skin.

Formation of disulphide-linked mu 2 omega 2 tetramers in pre-B cells by the 18K omega-immunoglobulin light chain

Pre-B cells are precursors of B lymphocytes that contain intracellular heavy-chain protein (mu) and are either yet to rearrange their light-chain genes or are in the process of doing so. These cells have traditionally been considered to contain intracellular mu-chain with no associated light chain. We demonstrate here that pre-B lymphoid lines synthesize a protein of relative molecular mass (Mr) 18,000 (18K), which we term omega, which forms disulphide-linked mu 2 omega 2 tetramers. This protein could be immunoprecipitated with mu-chain from pre-B lines, but not from T-cell and fibroblast lines that express transfected mu-genes, nor from a pre-B line that synthesizes a D mu-protein (which lacks a V domain). We view the omega-chain as being a pre-B specific surrogate light chain that may be essential for the important regulatory function that the mu-protein is believed to have at this stage of differentiation.

Complete evulsion of the globe and optic nerve

A 17-year-old boy had an evulsion of globe and optic nerve from an automobile accident. Computed tomography showed a severed optic nerve on the injured side. A visual field defect was demonstrated in the other eye.

Production of biologically active fragments of parathyroid hormone by isolated Kupffer cells

Cleavage of parathyroid hormone (PTH) by isolated Kupffer cells from rat liver was examined. Iodinated PTH labeled at position 43 was converted into two radioactive fragments which were shown by Edman degradation to have residues 35 and 38 as their NH2 termini. Cleavage at these positions is characteristic of cathepsin D. Amino-terminal fragments were detected by bioassay of fractions obtained by high performance liquid chromatography. These fragments eluted in positions characteristic of the 1-34 and 1-37 peptides also previously shown to be produced by purified cathepsin D. The putative 1-37 fragment was rapidly converted to 1-34 upon digestion with cathepsin D, whereas the putative 1-34 fragment was not further digested by this enzyme, behavior previously shown to be characteristic of 1-37 and 1-34 bovine PTH. Fragmentation of PTH as measured by generation of fragments soluble in trichloroacetic acid was inhibited by methylamine, monensin, and ammonium chloride. In addition, monensin significantly inhibited production of both carboxyl- and amino-terminal fragments. Finally, active PTH fragments were also produced by elicited peritoneal macrophages. It is concluded that Kupffer cells, and other macrophages, can produce active fragments of PTH which appear in the medium. These fragments may be generated by cathepsin D within the cells.

The effects of vanadate and molybdate on cathepsin D; relationship to ATP activation of lysosomal proteolysis

The effects of the phosphate analogues, vanadate and molybdate, on the ATP-activated enzyme, cathepsin D, were investigated. Both were found to inhibit proteolysis but this appeared to be the result of non-specific interactions with the protein substrates which result in precipitation, rather than interactions with the enzyme. Inhibition of proteolysis was induced by the same concentration of inhibitors as that which induced precipitation (measured by turbidity), and was dependent on the concentration of substrate. Precipitation did not occur at neutral pH but was maximal below pH 5. High concentrations of salt (greater than 1M KC1) prevented precipitation of proteins by vanadate and molybdate and under these conditions little inhibition of proteolysis was observed even at high inhibitor concentrations. Nonetheless, ATP was found to activate proteolysis catalyzed directly by lysosomal enzymes at acid pH, while vanadate and molybdate inhibited proteolysis in this system and induced precipitation of substrate. These results indicate that inhibition of proteolysis at acid pH by vanadate (or molybdate) has no relationship to inhibition of proteases and/or ATP dependence of such enzymes. However, direct activation of cathepsin D in lysosomes by ATP remains a viable hypothesis.