Biomedical subjects

R B Harris

Publications and source records attributed to R B Harris.

At least 19 recordsLinked to original sources

PubMed1992

Design and synthesis of a helix heparin-binding peptide.

Elaboration of heparin-protein-binding interactions is necessary to understand how heparin modulates protein function. The heparin-binding domain of some proteins is postulated to be a helix structure which presents a surface of high positive charge density. Thus, a synthetic 19-residue peptide designed to be alpha-helical in character was synthesized, and its interaction with heparin was studied. The peptide was shown to be 75% helix by circular dichroism (CD) spectrometry in neutral pH buffer (at 2 degrees C); helicity increased to nearly 85% under high ionic strength conditions or to nearly 100% in 75% ethanol. Increasing the temperature of the solution caused a change in the spectral envelope consistent with a coil transition of the peptide. The midpoint of the transition (i.e., the temperature at which the helix content was determined to be 50%) was 25 degrees C, and the determined van't Hoff enthalpy change (delta HvH) was 3.2 kcal/mol of peptide. By CD, heparin increases the helix content of the peptide to 100% and increases the apparent thermal stability of the peptide by about 1 kcal/mol. The melting point for the helix/coil transition of the heparin-peptide complex was 50 degrees C. The thermal coefficient of the transition (approximately 300 deg.cm2.dmol-1.degree C-1) was essentially the same for the peptide alone or the peptide-heparin complex. Dissociation of the complex under high ionic strength conditions was also observed in the CD experiment. Biological assays showed less heparin-binding activity than expected (micromolar KD values), but this was attributed to the absence of critical lysyl residues in the peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1992

Localization and characterization of a heparin binding domain peptide of human von Willebrand factor.

Human von Willebrand factor, a plasma glycoprotein which plays a critical role in regulating hemostasis, binds heparin, but the physiological importance and mode of this interaction is poorly understood. Using the motif of an amino acid sequence of a consensus heparin binding synthetic peptide, a 23-residue sequence (Tyr565-Ala587) of human von Willebrand factor was identified that retains the consensus motif and binds heparin with affinity comparable with native von Willebrand factor and the consensus peptide. In a fluid phase binding assay, the Tyr565-Ala587 peptide competed effectively with von Willebrand factor for binding heparin. Synthesis and testing of peptides overlapping Tyr565-Ala587, as well as adjacent cationic regions, showed this core sequence to be the optimal linear binding domain. Far ultraviolet circular dichroism spectrometry of the Tyr565-Ala587 peptide suggested that the peptide undergoes conformational change upon binding heparin. The Tyr565-Ala587 peptide thus encompasses part (or all) of a functionally important heparin binding domain of von Willebrand factor. Further study of this and related peptides may be useful for exploring how heparin may influence von Willebrand factor-mediated platelet hemostasis.

Amino Acid Sequence↗

PubMed1992

Characterization of homogeneous atrial granule serine proteinase, a candidate processing enzyme of pro-atrial natriuretic factor.

We previously reported the discovery and partial characterization of bovine atrial granule serine proteinase, a candidate processing enzyme of pro-atrial natriuretic factor, which is associated with atrial granule membranes. We now report the physicochemical properties of electrophoretically homogeneous enzyme purified by a series of chromatography steps from a subcellular fraction enriched for atrial granules. The enzyme tends to associate during purification to higher molecular weight species, but SDS-PAGE analysis reveals a single polypeptide chain of molecular weight 70,000. The enzyme is activated 2-3 fold by Ca+2 and 1.5-fold by Mg+2 and is nearly 100% inhibited by Zn+2 or Co+2. Thus, the enzyme can be considered a calcium activated, neutral pH, serine proteinase. Based on the hydrolysis of numerous synthetic peptide substrates, the recognition sequence for the enzyme within the pro-hormone has been mapped to A96PRSLRR102; cleavage occurs at the Arg98-Ser99 bond yielding bioactive atrial natriuretic peptide directly from the pro-hormone. The doublet of basic amino acids is part of the recognition sequence but is not the primary cleavage site. It is our hypothesis that the processing site sequence acts as a recognition element for the endoproteinase and resides at the surface of the pro-hormone and thus contributes to the molecular basis for limited proteolysis.

Amino Acid Sequence↗

PubMed1992

Prevalence of self-reported poor sleep in a healthy population aged 50-65.

Many population-based surveys have reported that the prevalence of poor sleep increases with age. Despite the uniformity of findings, it remains unclear to what extent age-related declines in overall physical health are related to those results. One approach to this problem has been to adjust for such confounding variables multivariately. Some prior studies using this approach have not shown the expected age-related increases in the prevalence of poor sleep. Another approach has been the study of sleep in carefully screened, healthy populations. The current study reports the prevalence of disturbed sleep in a population, ages 50-65, carefully screened for physical health as part of an ongoing study of exercise and cardiovascular function. The prevalence of self-reported trouble falling asleep every night or almost every night (1.1% M, 2.6% F), trouble awakening and returning back to sleep (4.4% M, 3.3% F), and use of hypnotic medication at least twice a week (1.6% M, 2.6% F) were consistently lower than in nearly all previous population-based studies of individuals of comparable age. This implies that when overall physical health factors are taken into account a decline in sleep quality is not necessarily an inevitable component of aging per se. As has been shown in other studies, there were small but statistically significant relationships between self-reported depression and poor sleep. Despite the low prevalence of poor sleep, about a third of the population reported feeling not well-rested and/or not getting the sleep they required. The individuals in this study also reported obtaining significantly less sleep relative to normative data from 30 years ago.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1992

Adipocyte insulin responsiveness in female Sprague-Dawley rats fed a low fat diet containing a fat-mimetic carbohydrate.

Two experiments examined the effects of replacing high fat with low fat diets on adipocyte insulin sensitivity and response. Female Sprague-Dawley rats had free access to diets containing 21% (control), 61% (high fat) or 2% (low fat) of energy as fat. In the low fat diet a carbohydrate-based fat-mimetic carbohydrate replaced all but the essential fat present in the high fat diet. Insulin-stimulated glucose utilization by isolated adipocytes was measured after 10, 30 or 50 d. In a second study adipocyte insulin saturation curves were measured after 36 d. Rats fed the high fat diet for 30 d were insulin resistant and adipocyte basal and insulin-stimulated glucose utilization were depressed. The low fat diet initially stimulated glucose utilization of adipocytes but did not change insulin responsiveness. After 50 d there was no difference in glucose utilization between adipocytes from rats fed control and low fat diets. Insulin resistance in rats fed the high fat diet was associated with a nonsignificant reduction in insulin receptor number. These observations do not exclude the possibility of a post-receptor defect in glucose utilization.

Adipose Tissue↗

PubMed1992

Insulin insensitivity is rapidly reversed in rats by reducing dietary fat from 40 to 30% of energy.

The objective of this study was to determine the effect of reducing dietary fat content from 40 to 30% of total energy on body composition and insulin sensitivity in rats. Female Sprague-Dawley rats were fed either a control diet (30% energy as fat) or a high fat diet (40% energy as fat) for 10 wk. In vivo glucose tolerance tests indicated that both basal and glucose-stimulated insulin concentrations were elevated in rats fed the high fat diet. Two groups of rats offered the high fat diet were then fed the control diet (HF,C) and two that had received the high fat diet were then fed a diet (30% energy as fat) containing a fat-mimetic carbohydrate (HF,M). Two groups continued to receive the high fat diet and two groups continued to receive the control diet. Rats were killed 1 and 2 wk after the diet switch. In vivo glucose tolerance tests indicated that insulin sensitivity was corrected in HF,C and HF,M rats after 3 d. Body fat content was greater in rats fed the high fat diet and remained high after 7 d of consuming either diet with 30% of energy from fat. There was no effect of diet on liver fatty acid utilization or on diaphragm glucose oxidation. Adipocytes from all treatment groups were insulin resistant, possibly due to feeding status or age of the rats. The results of this study suggest that a moderate reduction in fat intake, from 40 to 30% of energy, can produce a rapid improvement of insulin sensitivity in insulin-insensitive rats, independent of changes in body fat content and irrespective of the means used to reduce dietary fat content.

Adipose Tissue↗

PubMed1991

Processing enzyme specificity is a consequence of pro-hormone precursor protein conformation.

Peptide-hormones are synthesized as higher molecular weight, precursor proteins which must initially undergo limited endoproteolysis to yield the bioactive peptide(s). The ability of two different endoproteinases, gonadotropin-associated peptide (GAP)-releasing enzyme and atrial granule serine proteinase (which are likely to be the physiologically relevant processing enzymes of bovine hypothalamic pro-gonadotropin-releasing hormone/gonadotropin-associated peptide and bovine pro-atrial natriuretic factor precursor proteins, respectively), to act at their own recognition sequences within their relevant pro-hormone proteins has now been contrasted with their ability to act at the recognition sequence for the alternate enzyme or to act at their own recognition sequence when it is placed within the protein framework of the alternate precursor protein. The results show that each enzyme acts with specificity at its own recognition sequence even when it is placed within the framework of the alternate pro-hormone. However, the enzymes fail to act (or act in a non-specific manner) at the alternate recognition sequence even if it is placed within the peptide framework of its own pro-hormone protein. Thus, despite the fact that both recognition sequences are similar in sequence and residue composition and that both contain a doublet of basic amino acids, it appears that sequence and the local conformation assumed by the processing site within the pro-hormone protein are essential for each endoproteinase to act with fidelity. As part of our continuing work, we now also report several newly determined physicochemical properties of hypothalamic GAP-releasing enzyme, the processing enzyme of pro-gonadotropin-releasing hormone/GAP protein.

Amino Acid Sequence↗

PubMed1991

Mapping the active site of meprin-A with peptide substrates and inhibitors.

The extended substrate-binding site of meprin-A, a tetrameric metalloendopeptidase from brush border membranes of mouse kidney proximal tubules, was mapped with a series of peptide substrates. Previous studies led to the development of the chromogenic substrate Phe5(4-nitro)bradykinin for meprin-A. With this substrate, several biologically active peptides were screened as alternate substrate inhibitors, and, of these, bradykinin (RPPGFSPFR) was found to be the best substrate with a single cleavage site (Phe5-Ser6). Three types of bradykinin analogues were used for a systematic investigation of substrate specificity: (1) nonchromogenic bradykinin analogues with substitutions in the P3 to P3' subsites were used as alternative substrate inhibitors of nitrobradykinin hydrolysis, (2) analogues of nitrobradykinin with variations in the P1' position were tested as substrates, and (3) intramolecularly quenched fluorogenic bradykinin analogues with substitutions in the P1 to P3 sites were tested as substrates. A wide variety of substitutions in P1' had little effect on KM (174-339 microM) but markedly affected kcat (51.5 s-1 = A greater than S greater than R greater than F greater than K greater than T greater than E = 0). Substitutions in P1 had a greater effect on KM (366 microM-2.46 mM) and also strongly affected kcat (98.5 s-1 = A greater than F much greater than L greater than E greater than K = 2.4 s-1). The variety of allowed cleavages indicates that meprin-A does not have strict requirements for residues adjacent to the cleavage site. Substitutions farther from the scissle bond also affected binding and hydrolysis, demonstrating that multiple subsite interactions are involved in meprin-A action.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1991

Calorimetric and spectroscopic examination of the solution phase structures of prekallikrein binding domain peptides of high molecular weight kininogen.

Unique sequence-binding sites are exposed on the surface of high molecular weight kininogen which complex prekallikrein or factor XI with high affinity and specificity. A sequence comprising 31 residues of the mature kininogen molecule (Asp565-Lys595) retains full binding activity for prekallikrein (KD = 20 nM) and assumes a complex folded structure in solution which is stabilized by long-range interactions between N- and C-terminal residues. The sequence Trp569-Lys595 (27 residues) shows only 28% of this binding affinity and lacks the key structural features required for protein recognition (Scarsdale, J. N., and Harris, R. B., J. Prot. Chem. 9, 647-659, 1990). We were thus able to predict that N- or C-terminal truncations of the binding-site sequence would disrupt the conformational integrity required for binding. Two new peptides of 20- and 22- residues have now been synthesized and their solution phase structures examined. These peptides are N- and C-terminal truncations, respectively, of the 27-residue sequence and correspond to the sequences Asp576-Lys595 and Trp569-Asp590 of high molecular weight kininogen. The results of fluorescence emission and circular dichroism (CD) spectroscopies in the range 25-90 degrees C and from differential scanning calorimetry (DSC) all substantiate the idea that the C-terminal truncation peptide binds prekallikrein 35-fold poorer than the 31-residue peptide because it is relatively unordered and possesses a less stable structure. Surprisingly, the N-terminal truncation peptide (20-mer) shows structural stability even at elevated temperatures and, like the 31-residue peptide, undergoes cold-induced denaturation observable in the DSC. 2D-NMR analysis of the 20-residue peptide revealed two distinct structures; one conformer possesses a more compact, folded structure than the other. However, the predicted structures assumed by either conformer are very different from those of either the 31- or 27-residue peptides. Hence, the binding affinity of the 20-residue peptide is 60-fold poorer than that for the 31-residue peptide because it assumes a nonproductive binding conformation(s).

Amino Acid Sequence↗

PubMed1991

Characterization of liver epithelial cells transfected with myc and/or ras oncogenes.

While many liver tumors contain activated myc and ras oncogenes, the mechanisms by which these genes contribute to cellular transformation is poorly understood. Activated versions of the cellular oncogenes, c-myc and/or c-H-ras were transfected into normal rat liver epithelial cells to identify cellular pathways that are altered in the cells containing the oncogenes. The results of these and other investigations indicate that the biological properties associated with the transfection of c-myc include immortalization, reduced contact inhibition of growth, activation of phospholipase A2-mediated pathways, increased sensitivity to transformation with a ras gene, and greatly increased sensitivity to growth factors. The biological properties associated with the transfection of the ras gene include morphological transformation, anchorage-independent growth, tumorigenicity, increased phosphatidylinositol metabolism, the induction of growth-factor processing and secretion, which leads to (exogenous) growth factor-independent tumor growth, and a marked resistance to normal inhibitors of growth such as TGF-beta. It is proposed that the complementary actions of the myc and ras genes in cellular transformation may be related to the ras-induced secretion of autocrine growth factors by cells sensitized to their effects by the myc gene. The increased stimulus for growth coupled to a ras-induced insensitivity to growth inhibitors may lead to clonal expansion of these cells and tumor development.

Animals↗

PubMed1991

Determination of enzyme specificity in a complex mixture of peptide substrates by N-terminal sequence analysis.

A method has been developed to determine preferred residue substitutions in the P' position of peptide substrates for proteolytic enzymes. The method has been validated with four different enzymes; the angiotensin I-converting enzyme, atrial dipeptidyl carboxyhydrolase, bacterial dipeptidyl carboxyhydrolase, and meprin A. A mixture of N-acylated potential peptide-substrates for each of the enzymes was prepared in a single synthesis procedure on the same solid-phase synthesis resin. The peptides were identical in all residue positions except the P' position to be studied, into which numerous amino acid residues were incorporated on a theoretical equimolar basis. After cleavage and extraction of the peptides from the resin, no attempt was made to purify them individually; the exact concentration of each peptide in the mixture was determined by quantitative amino acid analysis. Incubation of an enzyme with its peptide-substrate mixture at [S] much less than Km yielded peptide hydrolytic products with newly exposed N-termini. The identity and amount of each hydrolysis product was determined by automated N-terminal sequence analysis. One cycle of sequencing revealed preferred amino acid substitutions in the P'1 position, two cycles the P'2 position, and so forth. Comparison of the rates of production of the various products indicates the preferred substitution in that particular P' position. New information on the substrate specificities of each of the enzymes tested was obtained and it is clear that this approach can be applied to any protease with a defined (or suspected) point of cleavage in a peptide substrate.

Amino Acid Sequence↗

PubMed1991

Gender differences in the reliability of reporting symptoms of angina pectoris.

Numerous studies have shown that the symptoms of angina pectoris are more prevalent in women than men, than other manifestations of coronary heart disease, with the greatest discrepancies at younger ages. Variation in symptom reliability between genders could be a potential explanation for these differences. The Lipid Research Clinics Prevalence Study included two standardized Rose Questionnaire interviews, allowing evaluation of the relationship between reliability and prevalence of angina pectoris. Analyses of the results of two interviews in 2348 men and 2085 women who were at least 30 years old in 1972-1976 showed that women generally had lower reliability estimates, but that the differences were minimal for age groups where prevalence differences were greatest. Furthermore, for interviews less than 1 month apart differences in symptom reliability were quite small (kappa = 0.65 for men and 0.58 for women). In addition, if consistently positive interviews were used to define angina, gender differences in prevalence decreased but did not disappear. In the LRC population, reporting unreliability did not explain the higher prevalence of angina pectoris in young women.

Adult↗

PubMed1991

Growth measurements in Sprague-Dawley rats fed diets of very low fat concentration.

Young (70 g) male Sprague-Dawley rats were fed one of four diets for 28 d to determine the effects of replacing dietary fat with a noncaloric substitute. Fat contributed 17% of energy in a control diet and 36% in a high fat diet. A fat substitute was used to produce two low fat diets in which essential fatty acid was the only source of lipid. One low fat diet (low fat 1) was similar in texture to the control diet. The other low fat diet (low fat 2) was comparable to the high fat diet. Digestible energy was 92-95% of gross dietary energy in all diets. There was no effect of diet composition on energy intake of the rats. At the end of the study, animals given low fat diets weighed approximately 20 g more than those fed control or high fat diets, due to increased lean body mass. Diet had no significant effect on body fat content, gastrocnemius muscle weight or femur length. This study indicates that increasing the protein:energy ratio of the diet by replacing nonessential fat with a fat substitute may promote deposition of lean tissue rather than fat in growing animals.

Animals↗

PubMed1991

Physiological response of mature rats to replacement of dietary fat with a fat substitute.

The effects of replacing dietary fat with a fat substitute on food intake, body composition and lipid metabolism were examined in rats. Female Sprague-Dawley rats (250 g) were fed diets containing between 2 and 63% of energy as fat for 64 d. Inclusion of a substitute resulted in diets of different fat content but similar texture. When 10% corn oil (21% kJ-fat diet) was replaced with the substitute supplemented with linoleic acid (2% kJ-fat diet), rats increased food intake so that there was no effect on energy intake, body weight, body composition or serum lipid profile. Rats fed a diet containing 10% corn oil and 30% Crisco vegetable shortening (63% kJ-fat diet) became obese and hyperinsulinemic. When half (51% kJ-fat diet) or all (30% kJ-fat diet) of the Crisco was replaced with the fat substitute, the rats increased food intake and were fatter than controls but less obese than rats fed the 63% kJ-fat diet. Hepatic lipid oxidation and ketone synthesis were proportional to the percentage of dietary energy as fat. Adipocyte de novo lipid synthesis was inhibited by 51% kJ-fat and 63% kJ-fat diets. Partial or total replacement of Crisco prevented the hyperinsulinemia observed in 63% kJ-fat rats, suggesting a protective effect against the development of insulin resistance with diet-induced obesity.

Animals↗

PubMed1991

Pro-gonadotropin-releasing hormone protein is processed within hypothalamic neurosecretory granules.

Peptide-hormones are synthesized as higher-molecular-weight precursor proteins which must undergo numerous posttranslational modifications to yield the bioactive peptide(s) which may include limited endoproteolysis, limited exopeptidase digestion, and C-terminal amidation. Three different enzymes which are likely to be the physiologically relevant processing enzymes of bovine pro-gonadotropin-releasing hormone (pro-GnRH) precursor protein have been colocalized to, and purified from, hypothalamic neurosecretory granules. Gonadotropin-releasing-hormone-associated-peptide-releasing enzyme initiates processing by endoproteolysis of the pro-hormone exclusively at the Arg 13-Asp 14 bond in the sequence, -Gly6-Leu-Arg-Pro-Gly 10-Gly-Lys 12-Arg 13-Asp-, which overlaps the sequence for GnRH (1-10) and GAP(14-69) within the pro-protein. Hypothalamic carboxypeptidase E then sequentially removes the -Lys12-Arg13- doublet from the newly formed peptide before peptidyl glycine alpha-amidating monooxygenase catalyzes the formation of amidated GnRH. Carboxypeptidase E activity is stimulated in vitro by cobalt ion and removes the Lys and Arg residues with equal facility. The residue which acts as the amide nitrogen donor for the alpha-amidating enzyme must be present as the free C-terminal residue of a substrate; the enzyme does not recognize peptide substrates with C-terminal extensions. Based on the mandatory ordered events for processing pro-GnRH and the relative pH profiles displayed by these enzymes, our results are consistent with the idea that endoproteolysis of the pro-hormone occurs upon formation of the secretory granule at the Golgi apparatus and that the processed peptides are the storage form within the secretory vesicles.

Amino Acid Sequence↗

PubMed1990

Solution phase conformation studies of the prekallikrein binding domain of high molecular weight kininogen.

High molecular weight kininogen is a cofactor of the surface-dependent phase of the blood-clotting cascade. Unique sequence-binding sites are exposed on the surface of this glycoprotein which complex prekallikrein or factor XI with high affinity and specificity (Tait and Fujikawa, 1987). A sequence comprising 31-residues (residues 565-595 of the mature kininogen molecule) retains full binding activity for prekallikrein but the sequence 569-595 (27 residues) shows only 25% of this binding affinity (Vogel et al., 1990). Thus, the key structural features required for protein recognition reside in the 31-residue sequence but these features are likely compromised (or absent) in the 27-residue sequence. To determine the conformation of the prekallikrein-binding domain, peptides comprising the 31- and 27-residue sequences were prepared by solid-phase methods and their structures determined by circular dichroism, fluorescence polarization, and 2D-NMR techniques. Fluorescence emission spectra, polarization, and anisotropy measurements of the single Trp residue present in both peptides show that the 31-residue peptide contains an ordered microenvironment at its amino terminus, which is not present in the 27-residue peptide. This structural ordering is characterized by movement of the Trp residue into a more polar environment. Further, the 31-residue peptide possesses a higher limit anisotropy, longer rotational relaxation time, and shows a higher polarization value even at elevated temperatures. Circular dichroic spectra of both peptides in the far UV region are essentially identical and indicate that both peptides contain predominantly beta-turn elements, but also contain some alpha-helix, beta-sheet, and random coil character. The structural elements of both peptides are unchanged in urea solution, but the negative ellipticity absorption band in the near UV region assignable to Trp is eliminated in acid solution upon protonation of the neighboring-Asp-Asp-Asp- triplet. In the two peptides, the spin system of each amino acid has been assigned through 2D-1H scalar coupling correlated experiments; pure absorption NOESY experiments were used to determine through-space connectivities. The results are entirely consistent with the previous experiments in that both peptides contain predominantly beta-turn elements and the amino terminus of the 31-residue peptide is highly ordered in comparison with the 27-mer; in fact, this region is likely to be helical in nature.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗

PubMed1979

Freedom from transmission of hepatitis-B of gamma-globulin and heat-inactivated plasma protein fraction prepared from contaminated human plasma by fractionation with solid-phase polyelectrolytes.

Plasma contaminated with hepatitis B surface antigen (HBsAg) and shown by others to be infectious when injected in a dilution of 1:1,000,000 in chimpanzees, was fractionated by a solid-phase polyelectrolyte (PE) procedure for its content of plasma protein fraction (PPF) and gamma-globulin (immune serum globulin; ISG). Quantitative Ausria II radioimmunoassays showed that nearly half the HBsAg was bound by the PE and could be eluted at low pH, while the rest was found in the heat-inactivated PPF. When the ISG was concentrated to 16%, the 13 mg/kg (comparable to a human dose) was injected intramuscularly in 6 chimpanzees, or when the PPF was heated at 60 degrees C for h and injected intravenously in 2 chimpanzees, there was no clinical or laboratory evidence of hepatitis B infection after 12 months, although 1 chimp of 2 who received the same material showed a borderline positive anti-HBsAg antibody result on one of 52 weekly serum samples. Since the new PE fractionation method is essentially nondenaturing, and simpler than the classical ethanol procedures, it was important to establish the noninfectivity of the final products.

Adsorption↗

PubMed1979

Lichenoid delayed hypersensitivity reactions in tattoos.

Two patients with an inflammatory reaction in a red tattoo had histopathologic changes of lichen planus. The lesions demonstrated a lymphocytic bandlike infiltrate, liquefaction degeneration, acanthosis, hypergranulosis, and orthokeratosis and many hyaline bodies. Metal particles were observed in the region of the dermal-epidermal reaction. This probably is another example of the lichenoid reaction produced by delayed cellular hypersensitivity.

Adult↗