The effect of antigen and mode of immunization on the allotypic distribution of enhanceable plaque-forming antibody

The relation between the genotypic control and phenotypic expression of antibody formation and between gene dose and product concentration depends on and is modified by antigen-mediated selection and by antigen-induced cell division. This dependence was studied in terms of allotypic specificities of rabbit light chain as markers and with different antigens and. regimens of immunization. The number of enhanceable plaque-forming cells of the same allotype was measured in the spleens of rabbits, homozygous and heterozygous at the A_b locus. A significant departure from a simple gene-dose relationship was observed. The regular preponderance of one allotype over another (“pecking order”: A4>A6>A5>A9) was confirmed. The preponderance in A⁴/A⁵ animals was found to persist whether the allotype ratio of enhanceable plaques was tested after one, two or ten injections with SRBC, after immunization with chemically modified SRBC or with DNP-HGG. There was no significant difference in the cross-reactivity of A4 and AS plaque-forming SRBC antibody. The distribution of allotype ratios of responding A⁴/A⁵ animals changed with prolonged immunization from trimodal to bimodal and finally approached unimodality. After two injections with SRBC, the incidence of individual heterozygotes, making a monoallotypic enhanceable plaque response, was greatest among animals with allotypes from the extremes of the pecking order (i.e. A⁴/A⁹). We can account for our observations and for the distribution of allotype ratios in the response to strong and to weak antigen on the basis of the following assumptions:

• I a small number of receptor-carrying precursors of antibody-forming cells is involved in the response to one cr two injections with antigen;
• II the specificity spectrum for antigens which evoke a heterogeneous response is the same for plaque-forming antibodies of different allotypic specificity (A4 or A5);
• III in heterozygotes, the ratio of receptors with different allotypic specificities is different from 1 and is related to the distance in the pecking order; the greater the distance, the greater the difference from 1;
• IV there is continuous recruitment from precursor cells during prolonged immunization.

     

Human papillomavirus typing with a polymerase chain reaction-based genotyping array compared with type-specific PCR

BACKGROUND: Type-specific persistence of human papillomavirus (HPV) infection can cause invasive cervical cancer. OBJECTIVES: To evaluate the efficacy of HPV detection and typing with a general polymerase chain reaction (PCR)-based genotyping array and to compare it with a type-specific PCR assay. STUDY DESIGN: Four hundred and thirty-three cervical samples were tested with a modified MY11/GP6+ PCR-based reverse-blot assay (EasyChip HPV Blot; King Car, Taiwan [hereafter HPV Blot]) and with 20 genotypes of L1-type-specific PCR (HPV-6, -11, -16, -18, -31, -33, -35, -39, -45, -51, -52, -53, -56, -58, -59, -62, -66, -68, -70, and -71 [CP8061]). RESULTS: The concordance of the two tests in determining HPV positivity was 96.8% (419/433), with a Cohen's kappa=0.93 (95% CI: 0.90-0.97) and McNemar's test of P=1.0, which indicates excellent agreement. The overall concordance of the two tests in the identification of type-specific HPV was 91.0% (394/433). Sensitivity (90-100%), specificity (99.2-100%), and accuracy (98.6-100%) rates of HPV Blot against the gold standard were satisfactory for HPV-16, -18, -58, -33, -52, -39, -45, -31, -51, -70 while HPV-71 (63.6%) had suboptimal sensitivity. Though the kappa values between the two tests for many individual genotypes could not be reliably calculated because of low positivity, the kappa values for HPV-16, -52, and -58 were excellent (0.93, 0.96, and 0.95, respectively). CONCLUSION: The modified MY11/GP6+ PCR-based HPV Blot assay is accurate and sensitive for detection and genotyping of HPV in cervical swab samples.     

Determination of biogenic amines in fish implicated in food poisoning by micellar electrokinetic capillary chromatography

A micellar electrokinetic capillary chromatography (MECC) method for the simultaneous determination of seven biogenic amines in fish was developed. The peaks of all components were successfully separated within 11.5 min. MECC was performed with 0.06 M sodium deoxycholate in 0.02 M borate buffer (pH 9.2)-methanol (95:5, v/v) solvent. The average recoveries for all components ranged from 84.4 to 100.3%. The application of this method to detect amines in fried marlin fillet implicated in a food poisoning incident indicated that a high level (56.24 mg/100 g) of histamine was present in the sample. Another 10 fish samples collected from markets were also analyzed and did not contain detectable levels of histamine (<2.5 mg/100 g).     

Inconsistent effects of all-trans retinoic acid on different clones of chemically transformed rat liver epithelial cells

The effects of all-trans retinoic acid (RA) on the growth andbiochemical properties of five clonal strains of neoplasticallytransformed rat liver epithelial cells were studied. These cellstrains were derived clonally from a single line of normal diploidrat liver epithelial cells that had been transformed by treatmentwith N-methyl-N'-nitro-N-nitrosoguanidine. The results showthat RA induces inconsistent alterations in selected phenotypicproperties of these five different cell strains. Retinoic acideither depressed, enhanced or produced no effect on the colony-formingability in soft agar, on the activity of -glutamyl transpeptidase,on the amount of cell-associated fibronectin, and on the bindingcapacity of ¹²⁵I-epidermal growth factor (EGF). The only consistentcorrelation observed among cell strains was between the cellularability to grow in soft agar and the amount of cell-associatedfibronectin. Enhancement of anchorage-independent growth byretinoic acid was not mediated through changes in the numberof EGF receptors. Our data demonstrate that the responses toretinoic acid of clonal subpopulations of chemically transformedrat liver epithelial cells are inconsistent, even when the clonalsubpopulations are derived from a common precursor.     

Induction of spheroid cytoplasmic bodies in a rat muscle by local tetanus

The term "cytoplasmic body" or "spheroid body" myopathy refers to a heterogeneous group of familial or sporadic diseases characterized primarily by the presence of abundant spheroid or cytoplasmic bodies in the muscles. The morphogenesis of these inclusions remains unclear. This article describes the induction and evolution of spheroid cytoplasmic bodies (SCBs) in the rat plantaris muscle (PL) with local tetanus, which was induced in rats by the injection of a minute amount of tetanus toxin. In contrast to the tetanized soleus muscle (SOL), which developed core fibers (central cores, minicore, target fiber, targetoid fiber, and rods), the tetanized PL produced numerous SCBs with a predictable time course. They were induced in both type 1 and 2 fibers of PL, which is composed predominantly (95%) of type 2 fibers, in contrast to SOL (85% type 1 fibers). Factors inducing SCBs may include immobilization, shortening, intact innervation, and disuse atrophy.     

Effects of low-level microwave irradiation on amphetamine hyperthermia are blockable by naloxone and classically conditionable

In a series of experiments, we investigated the effects of pulsed low-level microwave irradiation on amphetamine-induced hyperthermia in the rat. Rats were irradiated in a 2,450-MHz cylindrical waveguide exposure system at 1 mW/cm², 2 s pulses, 500 pps, average SAR of 0.6 W/kg. Acute (45 min) exposure to microwaves attenuated amphetamine-induced hyperthermia. This effect was blocked by pretreatment of the animals with the narcotic antagonist naloxone. In another experiment, rats were subjected to ten daily sessions of microwave exposure (45 min/session). On day 11, amphetamine-induced hyperthermia was studied in the animals immediately after a session of either microwave or sham exposure. Similar to the acute effect, amphetamine-induced hyperthermia was attenuated in rats irradiated with microwaves (unconditioned effect). In the sham-irradiated animals we observed a potentiation of the amphetamine-induced hyperthermia, which was a conditioned effect of microwaves. Thus, the conditioned effect (potentiation) was opposite in direction to the unconditioned effect (attenuation). No tolerance developed to the unconditioned effect after subchronic exposure. Furthermore, both conditioned and unconditioned effects of microwaves on amphetamine-induced hyperthermia could be blocked by treatment with naloxone. These data suggest that (1) microwave irradiation may activate endogenous opioids, which in turn alter the actions of psychoactive drugs, and (2) the effect of microwaves on drug action can be classically conditioned. Offprint requests to: H. Lai     

Hypertrophic mononeuritis clinically presenting with painful legs and moving toes

A 40-year-old woman presented with progressive lower leg pain and spontaneous toe movement. The EMG showed a posterior tibial nerve mononeuropathy and continuous myokymic discharges in posterior tibial-innervated muscles. The MRI revealed a markedly enlarged posterior tibial nerve. Toe movements and myokymia were unaffected by the proximal transection of the lesion but ceased abruptly when the distal end of the fusiform "tumor" was resected, suggesting that spontaneous electrical foci may have been located along the nerve lesion. The markedly enlarged nerve segment contained edematous, swollen fascicles with marked Schwann cell onion-bulb lesions and angiocentric, lymphocytic, and lymphofollicular infiltration. This nerve lesion is an example of a newly recognized entity called hypertrophic mononeuritis.     

Synthesis and anti-HIV-1 activity of 2'-"up"-fluoro analogues of active anti-AIDS nucleosides 3'-azido-3'-deoxythymidine (AZT) and 2',3'-dideoxycytidine (DDC).

1-(3-Azido-2,3-dideoxy-2-fluoro-beta-D-arabinofuranosyl)thymine (6, F-AZT) and 1-(2,3-dideoxy-2-fluoro-beta-D-threopentofuranosyl)cytosine (12, F-DDC) were synthesized from the potent antiherpes virus nucleosides 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)thymine (1, FMAU) and 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodocytosine (FIAC) in the hope that introduction of a 2-"up"-fluoro substituent might potentiate the anti-HIV activity of AZT and DDC. FMAU (1) was converted in three steps into 2,3'-anhydro-1-(2-fluoro-2-deoxy-5-O-trityl-beta-D-lyxofuranosyl)thymine (4), which when treated with NaN3 followed by detritylation afforded 6. F-DDC was prepared by two methods. Tritylation of FIAC followed by treatment of the product with thiocarbonyldimidazole afforded the 5'-O-trityl-3'-O-(imidazolyl)thiocarbonyl nucleoside 9. Upon radical reduction of 9 with Bu3SnH and AIBN, 5'-O-trityl-DDC 10 was obtained. Compound 10 was detritylated to give 12, which (when obtained by this procedure) resisted crystallization, but the diacetate 12' was obtained in crystalline form. Alternatively, FAC (14) was converted into N4,O5'-dibenzoyl derivative 15, which was treated with thiocarbonyldiimidazole. Reduction of 16 with Bu3SnH/AIBN followed by debenzoylation afforded 12, which was obtained in crystalline form. F-AZT did not exhibit any significant activity against the human immunodeficiency virus (HIV) in vitro. F-DDC, however, showed activity against HIV-1, but the therapeutic index is much inferior to that of AZT.