Origin of innervation in the feline ophthalmic artery

In this study, we investigate the innervation to the feline ophthalmic artery by the horseradish peroxidase (HRP) tracing method. Five adult cats with body weights ranging between 2.0 and 3.0 kg were used. Under microscopic dissection, the ophthalmic artery was identified and isolated. A gelfoam (Upjohn Co.), 1 x 3 mm in size, containing 0.1 ml of HRP was applied to the prepared artery segment for 2 h. The cat was sacrificed 3 days later. The trigeminal, stellate, superior cervical, middle cervical and nodal ganglia, and oculomotor, trochlear and abducens nuclei were removed, sectioned and stained for HRP-positive cells. HRP-labeled neurons were found in the ipsilateral trigeminal (TRG) and superior cervical ganglia (SCG). The middle cervical, stellate, Edinger-Westphal, trochlear and abducens nuclei were all deemed negative for HRP-labeled cells. In the TRG, HRP-labeled neurons ranged from 21 to 250 (mean +/- SE = 93.8 +/- 42.5/ganglion). The labeled neurons were distributed primarily in the ophthalmic branch. In the SCG, the HRP-labeled neurons were distributed evenly in the ganglion, ranging from 6 to 180 (mean +/- SE = 91.6 +/- 31.5/ganglion). Two additional cats having received a sham operation revealed a negative finding. The feline ophthalmic artery is innervated by the ipsilateral TRG and SCG. Such innervation may play a role in regulating blood flow to the optic nerve.

Liberal use of a bag made from a surgical glove during laparoscopic surgery for specimens retrieval

Laparoscopic surgery has been gaining wide acceptance in recent years. Tissue removal from the abdominal cavity becomes a paramount issue, especially when the specimen is infected, contains several fragments, or potentially contains a malignancy. Several sophisticated instruments and devices have been designed for this purpose. However, most of these are expensive, difficult to handle, and come in a fixed size. Condoms, glove fingers, and zipper-type plastic bags have been tried also, but with limited success. The authors report use of a simple bag made from a surgical glove to collect specimens; a long purse-string suture surrounds the opening or the base of the glove finger to secure material during retrieval. This method has been found to be simple and convenient, and necessary construction material is readily available. The bag not only protects the specimen from contact with the wound but also cuts short the operating time. The technique and advantages are described.

The effects of chemical remediation treatments on the extractability and speciation of cadmium and lead in contaminated soils

Two rural soils contaminated by cadmium (Cd) and lead (Pb) were used to evaluate the effect of different chemical treatments on changes in speciation and extractability of Cd and Pb, and in phytoavailability to wheat. Triplicates of seven chemical treatments were tested to compare and evaluate the remediation techniques for contaminated soils using pot experiments. Treatments applied were calcium carbonate, a high quantity of phosphate salt, hog composts, iron oxide, manganese oxide, zeolite, and unamended control. Wheat (Triticum aestivum) was planted in the different amended soils for a further one month to evaluate the effectiveness of treatments on uptake of Cd and Pb by the wheat shoots. Results indicated that addition of calcium carbonate, manganese oxide, or zeolite reduces the extractability of Cd or Pb in both soils, and significantly reduce the uptake of Cd and Pb by wheat shoots. Changes in the extractability and metal sequential fractionations indicate that the exchangeable (or available) form of Cd and Pb in two soils can be transformed into unavailable forms after these amendments.

Recurrent fungal keratitis and endophthalmitis

PURPOSE

To report a case of recurrent fungal sclerokeratitis and endophthalmitis with a very successful outcome due to aggressive combined surgical and medical therapy. To discuss the management of this potentially devastating infection.

METHODS

A 65-year-old man presented with 6 months of left eye redness and irritation after injury from organic matter propelled from an airboat. Initially, he had been treated with foreign body removal, antibiotics, and steroids. He was diagnosed with reactive sclerokeratitis at presentation and was treated with steroids. However, when he did not improve, cultures were obtained and Acremonium species filamentous fungi was identified. Despite treatment with appropriate topical and systemic antifungals, his fungal sclerokeratitis progressed to endophthalmitis. Two therapeutic penetrating keratoplasties (PKs) with iridectomy and intraocular amphotericin B were necessary to eradicate the fungal infection.

RESULTS

Visual acuity was restored to 20/25-3 with correction 9 months after initial presentation. There was no recurrence of fungal infection after the second therapeutic PK.

CONCLUSION

The possible reasons for recurrence of fungal infection are discussed. The role of timely and aggressive medical and surgical intervention for fungal sclerokeratitis and endophthalmitis in restoring excellent vision is emphasized.

[Experience of application of skin flap in repairing 112 patients with severe thermo pressure injury of hand]

OBJECTIVE

To investigate the clinical effect of skin flaps repairing severe thermopressure injury of hand.

METHODS

From January 1989 to December 1998, 112 patients with severe thermopressure injury of hand were repaired by various skin flaps transfer, the size of skin flaps was 6 cm x 8 cm to 12 cm x 18 cm. Postoperative patients were treated by combined rehabilitation in early stage.

RESULTS

All the flaps were survived with satisfactory effect. Sixty-six patients were followed up 6 to 12 months, skin flaps all showed better colour and texture, and function of the hand was satisfactory.

CONCLUSION

Different skin flaps are adopted to repair severe thermopressure injury of the hand according to different skin defects of the hand, combined early rehabilitation treatment, to achieve good recovery of function and appearance of the hand to the greatest extent.

cDNA structure, genomic organization, and promoter analysis of the mouse intestinal peptide transporter PEPT1

We describe in this report the cDNA structure, functional characteristics, genomic organization, and promoter analysis of the mouse H(+)-coupled low-affinity peptide transporter PEPT1. The mouse PEPT1 cDNA cloned from a kidney cDNA library is approximately 3.1 kb long and encodes a protein of 709 amino acids. When expressed heterologously in mammalian cells and in Xenopus laevis oocytes, mouse PEPT1 mediates H(+)-coupled electrogenic transport of the dipeptide glycylsarcosine. The mouse pept1 gene, cloned from a genomic DNA library in bacterial artificial chromosome, is approximately 38 kb long and consists of 23 exons and 22 introns. 5'-Rapid amplification of cDNA ends with poly(A)(+) RNA from mouse intestine has identified the transcription start site that lies 31 bp upstream of the translation start site. The promoter region upstream of the transcription start site does not contain the TATA box but possesses three GC boxes which are the binding sites for the transcription activator SP1. Functional analysis of the promoter region using the luciferase reporter assay in Caco-2 cells (a human intestinal cell line that express PEPT1 constitutively) and five different 5'-deletion fragments of the promoter has shown that essential promoter/enhancer elements are present within 1140 bp upstream of the transcription start site.

Variations of the cystic artery in Chinese adults

The origin and course of the cystic artery related to the Calot triangle were studied in 72 autopsies. The cystic artery arises from many possible origins; the right hepatic artery is the most common origin (76.6%). The Calot triangle (hepatocystic triangle), which is an important imaginary referent area for biliary surgery, is bounded by the common hepatic duct (CHD), the cystic duct, and the cystic artery. Of all the cystic arteries, 86.1% coursed through the Calot triangle, and 100% of the cystic arteries originating from the right hepatic artery coursed through the Calot triangle. However, only 54% of the cystic arteries that originated from the left, bifurcation, proper, and common hepatic arteries ran through the triangle. None of the cystic arteries that originated from the gastroduodenal, celiac, superior mesentery, or superior pancreaticoduodenal arteries passed through the triangle. Furthermore, 72.7% of the cystic arteries that originated from the right hepatic artery ran beneath the CHD as they entered the Calot triangle; the others ran anterior to the CHD. Of the cystic arteries that arose from locations other than the right hepatic artery, 29.4% ran posterior to the CHD, and 11.8% ran anterior to the CHD. The current study provides detailed information about anatomic variance in Chinese adults that may help avoid injury during open or laparoscopic cholecystectomies.

Changes in superoxide dismutase activity and mRNA in vivo after short-term supplementation with trilinolein in rats

BACKGROUND

Oxidative damage plays a central role in atherogenesis and antioxidation defense mechanisms may prevent atherosclerosis. This study evaluated the effect of short-term supplementation of the natural lipophilic antioxidant trilinolein on superoxide dismutase (SOD) activity and SOD-mRNA gene expression in vivo in rat vital organs.

METHODS

Male Wistar rats (n = 8) were injected intraperitoneally with trilinolein (1 mM/ml/kg/day in 0.5% ethanol) daily for three consecutive days. Two control groups (n = 8) were administered saline or 0.5% ethanol in saline, respectively, for three days.

RESULTS

Assay of SOD activity and SOD-mRNA by Northern blotting in rat liver, spleen and brain showed significant increases in SOD activity and increased SOD-mRNA gene expression.

CONCLUSIONS

The natural lipophilic antioxidant trilinolein potentiates the SOD antioxidation defense mechanism and increases gene expression of SOD-mRNA after short-term supplementation in rats.

Localization of sympathetic postganglionic neurons innervating mesenteric artery and vein in rats

Physiological and histochemical studies have demonstrated the control and innervation of sympathetic nerves to the artery and vein vessels of splanchnic circulation. In our laboratory, we first used the technique of retrograde transport of horseradish peroxidase to identify the origin of sympathetic neurons innervating the mesenteric vein. In this study, double fluorescence staining technique was used for a simultaneous localization of the sympathetic postganglionic neurons supplying the mesenteric artery and vein in rats. First-order branches of mesenteric artery (A) and vein (V) in the vicinity of ileo-cecal junction were isolated for application of fluorescent dyes (Fast Blue, FB and Diamidino Yellow, DY). The application of FB and DY on A and V was alternated in the next animal to minimize the difference in dye uptake. The animal was allowed to recover for 6-7 days assuring a complete uptake of FB and DY into the cytoplasm and nucleus, respectively. The number of FB, DY and double staining neurons in the prevertebral and paravertebral ganglia were counted under a fluorescent microscope after animal fixation and serial frozen section (30 microm) of the sympathetic ganglia. Our study revealed the following findings: (1) Distribution of the fluorescence-staining neurons in the sympathetic ganglia was as follows: right celiac ganglion (39%), superior mesenteric ganglion (30%), left celiac ganglion (26%), inferior mesenteric ganglion (1%) and paravertebral ganglia (4%). (2) Double staining neurons that dually innervate A and V amounted to 54% of total staining neurons. There were 41% neurons singly innervating A and 5% innervating V. (3) The ratio of neurons supplying the A and V ranged from 1.41 to 1.75 (average 1.61). (4) There was no distinct topographical distribution with respect to the neuron location innervating A and V. The distribution of neurons appeared in a scattering pattern.

A novel H(+)-coupled oligopeptide transporter (OPT3) from Caenorhabditis elegans with a predominant function as a H(+) channel and an exclusive expression in neurons

We have cloned and functionally characterized a novel, neuron-specific, H(+)-coupled oligopeptide transporter (OPT3) from Caenorhabditis elegans that functions predominantly as a H(+) channel. The opt3 gene is approximately 4.4 kilobases long and consists of 13 exons. The cDNA codes for a protein of 701 amino acids with 11 putative transmembrane domains. When expressed in mammalian cells and in Xenopus laevis oocytes, OPT3 cDNA induces H(+)-coupled transport of the dipeptide glycylsarcosine. Electrophysiological studies of the transport function of OPT3 in Xenopus oocytes show that this transporter, although capable of mediating H(+)-coupled peptide transport, functions predominantly as a H(+) channel. The H(+) channel activity of OPT3 is approximately 3-4-fold greater than the H(+)/peptide cotransport activity as determined by measurements of H(+) gradient-induced inward currents in the absence and presence of the dipeptide using the two-microelectrode voltage clamp technique. A downhill influx of H(+) was accompanied by a large intracellular acidification as evidenced from the changes in intracellular pH using an ion-selective microelectrode. The H(+) channel activity exhibits a K(0.5)(H) of 1.0 microM at a membrane potential of -50 mV. At the level of primary structure, OPT3 has moderate homology with OPT1 and OPT2, two other H(+)-coupled oligopeptide transporters previously cloned from C. elegans. Expression studies using the opt3::gfp fusion constructs in transgenic C. elegans demonstrate that opt3 gene is exclusively expressed in neurons. OPT3 may play an important physiological role as a pH balancer in the maintenance of H(+) homeostasis in C. elegans.

A wavelet-frame based image force model for active contouring algorithms

This paper proposes a directional image force (DIF) for active contouring. DIF is the inner product of the zero crossing strength (ZCS) of wavelet frame coefficients, and the normal of a snake, by representing strength and orientation of edges at multiple resolution levels. DIF markedly improves the immunity of snakes to noise and convexity.

Estimation of 2-D noisy fractional Brownian motion and its applications using wavelets

The two-dimensional (2-D) fractional Brownian motion (fBm) model is useful in describing natural scenes and textures. Most fractal estimation algorithms for 2-D isotropic fBm images are simple extensions of the one-dimensional (1-D) fBm estimation method. This method does not perform well when the image size is small (say, 32x32). We propose a new algorithm that estimates the fractal parameter from the decay of the variance of the wavelet coefficients across scales. Our method places no restriction on the wavelets. Also, it provides a robust parameter estimation for small noisy fractal images. For image denoising, a Wiener filter is constructed by our algorithm using the estimated parameters and is then applied to the noisy wavelet coefficients at each scale. We show that the averaged power spectrum of the denoised image is isotropic and is a nearly 1/f process. The performance of our algorithm is shown by numerical simulation for both the fractal parameter and the image estimation. Applications to coastline detection and texture segmentation in a noisy environment are also demonstrated.

Growth of Qinghai Tibetans living at three different high altitudes

This study compares the stature, weight, skinfolds, upper arm muscle area, and chest dimensions of Tibetan children, adolescents, and young adults who were born and raised, or who had lived from infancy, at 3,200 m, 3,800 m, and 4,300 m in Qinghai Province, People's Republic of China. While the individuals measured in Qinghai are among the tallest and heaviest Tibetans reported in the literature, they are nevertheless smaller and lighter than well-off children living at low altitude. The pattern of size variation among Tibetan males and females measured at the three high altitudes, along with evidence of a secular trend at 4,300 m, suggests that nutrition may significantly effect growth at high altitude. Only minor differences in thorax dimensions exist between Tibetan males and females measured at 3,200 m and 3,800 m. However, Tibetan males at 4,300 m possess slightly narrower and deeper chests (during and after adolescence) than males at 3,200 m and 3,800 m. Since individuals from 3,800 m and 4,300 m belong to the same local populations, this characteristic is unlikely to be genetically determined. However, it may be related to differences in the degree of hypoxia or to the influences of other environmental conditions.

Target-dependent axonal sprouting following vagal-hypoglossal nerve anastomosis in cats

PURPOSE

To investigate the relationships between the axonal sprouting and target neurotization by central neurons after nerve heteroconnection.

METHODS

Unilateral (right) vagal-hypoglossal nerve anastomosis (VHA) was performed in adult cats. Following 3-315 days postoperation (dpo), quantitative analyses and ultrastructural changes in the proximal portion of the vagal-hypoglossal heteroconnected nerve as well as the time course of neuronal regeneration were studied. Along with this, horseradish peroxidase (HRP) retrograde tracing technique was used to label the neurons of dorsal motor vagal nucleus (DMV) and nucleus ambiguus (NA) to ascertain if target neurotization was established.

RESULTS

The contralateral (left) intact vagus nerve proximal to the level of ansa cervicalis showed an average of 33 ± 1 myelinated and 74 ± 4 unmyelinated axons in 727 μm2 sectional area of the nerve. In the heteroconnected nerve at the corresponding level just proximal to the anastomosis site, there was a marked increase in the number of small axons sprouting from the unmyelinated nerve fibers between 18 and 25 dpo. The number of these axonal sprouts appeared to decline at 32 dpo but its increase of 131 % was sustained until the late regeneration stage at 315 dpo when compared with the contralateral nerve serving as a control. The mean number of myelinated axons per area unit (727 μm2) was reduced to 18 at 3 dpo but was immediately restored to the normal range at 7 dpo. The retrograde labelling of neurons in both the DMV and NA was first detected at 22 dpo and was progressively increased peaking by about 67 dpo.

CONCLUSIONS

We conclude that compared with the unmyelinated axons, the myelinated axons may acquire a superior interaction with the new target. Furthermore, the postoperative neurotization of tongue muscles may initiate and facilitate the retraction of the redundant axonal sprouts.

The antihypertensive effect of the berberine derivative 6-protoberberine in spontaneously hypertensive rats

Berberine is a natural isoquinoline alkaloid found in plants of the Ranunculaceae and Berberidaceae families. Extracts from berberine-containing plants have been used as traditional Chinese folk remedies for centuries. The antihypertensive effects of the berberine derivative 6-protoberberine (PTB-6) were studied in spontaneously hypertensive rats (SHRs). In conscious SHRs, PTB-6 lowered the systolic blood pressure in a dose-dependent manner (6-PTB: 5 mg/kg, -31.1 +/- 1.6 mm Hg; 10 mg/kg, -42.4 +/- 3.1 mm Hg). Cardiac output using the thermodilution method was reduced in PTB-6-treated anesthetized SHRs with a tendency to decrease in heart rate. Injection of PTB-6 into the intracerebral ventricles of SHRs lowered the systolic arterial blood pressure and heart rate. The berberine derivative PTB-6 is an effective antihypertensive agent. The mechanism of the antihypertensive effect of PTB-6 is probably through a central sympatholytic effect.

[Changes and its measurement of intracellular Ca2+ during exposure to hyperbaric oxygen]

Objective. To investigate the rule of change of intracellular Ca2+ and its measurement method during exposure to hyperbaric oxygen (HBO). Method. Microfluorescence method was used to measure the changes of intracellular Ca2+ concentration in co-cultured endothelial cells (EC) and smooth muscle cells (SMC) in a specially designed miniature oxygen chamber. Result. (1) [Ca2+]i changes during HBO exposure can be clearly observed directly in the chamber. (2) Within 5 min during 0.2 MPa and 0.3 MPa HBO exposure, EC[Ca2+]i and SMC[Ca2+]i showed a tendency, to increase at first and then decrease with time throughout the exposures, especially the SMC[Ca2+]i. The EC ruptured under exposure to 0.4 MPa HBO. Conclusion. During HBO exposure, EC[Ca2+]i and SMC[Ca2+]i showed biphasic changes, which increased at first and then decreased. The technique and method used were reliable and suitable for investigating of intracellular [Ca2+]i changes under HBO.

Molecular characterization of genes in the GP41 region of baculoviruses and phylogenetic analysis based upon GP41 and polyhedrin genes

A newly sequenced Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) gp41 gene was used to reconstruct the phylogeny for gp41 by comparison with Autographa californica MNPV, Bombyx mori MNPV, Helicoverpa zea single nucleopolyhedrovirus (SNPV), Lymantria dispar MNPV, Orgyia pseudotsugata MNPV and Spodoptera frugiperda MNPV. The 3.5 kb fragment of the AgMNPV gp41 region not only contained the gp41 gene but also three other open reading frames that had significant homology with the very late factor (vlf-1) of baculoviruses, AcMNPV ORF78, AcMNPV ORF79, and one partial open reading frame homologous to AcMNPV ORF81. The reconstructed phylogenetic tree of baculovirus gp41 genes compared with the polyhedrin gene tree produced similar topologies. Two other phylogenetic trees were reconstructed based on either combined gp41 and polyhedrin nucleotide sequences (total evidence) or combined evolutionary histories of both genes (strict consensus tree). The former had an identical tree topology as the gp41 gene tree alone, and the latter lost resolution in the branch of AcMNPV and BmMNPV. Mutation rate analysis showed the gp41 gene had a higher nucleotide substitution rate than the polyhedrin gene, implying that the polyhedrin gene may have a different selection constraint than the gp41 gene. Both genes have nonsynonymous/synonymous substitution values close to 0.1, similar to other DNA viruses.

Radiation safety system of the B-Factory at the Stanford Linear Accelerator Center

The radiation safety system of the B-Factory accelerator facility at the Stanford Linear Accelerator Center is described. The radiation safety system, which is designed to protect people from prompt radiation exposure due to beam operation, consists of the access control system and the radiation containment system. The access control system prevents people from being exposed to the very high radiation levels inside a beamline shielding enclosure. The access control system consists of barriers, a standard entry module at every entrance, and beam stoppers. The radiation containment system prevents people from being exposed to the radiation outside a shielding enclosure due to either normal or abnormal operation. The radiation containment system consists of power limiting devices, shielding, dump and collimator, and an active radiation monitoring system. The inter-related elements for the access control system and radiation containment system, as well as the associated interlock network, are described. The policies and practices used in establishing the radiation safety system are also compared with the regulatory requirements.

Distribution of the superficial temporal artery in the Chinese adult

The superficial temporal artery is important in head and neck surgery. Ethnologic variation may affect surgical procedure. In this study, we evaluated the variations of the artery in Chinese adults. We measured its bifurcating location, the diameter of its vessels, and its relationship to nearby structures. A total of 26 cadavers with 52 superficial temporal arteries were examined in 3 consecutive years. The superficial temporal artery ran 1.14 cm anteriorly to the bony external auditory canal. The average diameters of the superficial temporal artery, frontal branch, and parietal branch were 2.14, 1.61, and 1.68 mm, respectively. In 45 of 52 cases (86.5 percent), bifurcation of the artery occurred well above the zygomatic arch. The present study thus demonstrated that the superficial temporal artery in the Chinese adult differs from that in the Caucasian and has provided a detailed anatomic distribution analysis of the superficial temporal artery in Chinese adults, which should benefit the clinician in dealing with operation procedures related to this artery.

Effect of capsaicin on the micturition reflex in normal and chronic spinal cord-injured cats

The effect of capsaicin (10-80 mg/kg sc) on reflex activity of the urinary bladder was examined in anesthetized normal as well as anesthetized and awake chronic spinal cord-injured (SCI) cats. In normal cats, capsaicin elicited a transient increase in the frequency of isovolumetric bladder contractions and reduced the volume threshold for inducing micturition, but did not depress the amplitude of bladder contractions or the reflex firing on bladder nerves. In anesthetized SCI cats, capsaicin depressed reflex bladder activity and firing on bladder nerves. In awake SCI cats, capsaicin initially decreased the volume threshold for inducing micturition; however, after a delay of 3-6 h the volume threshold increased and intravesical voiding pressure decreased. This effect persisted for 4-12 days. It is concluded that capsaicin-sensitive C fiber bladder afferents are not involved in initiating reflex micturition in normal cats, but play an essential role in triggering automatic micturition in chronic SCI cats. The results are consistent with the clinical data indicating that C fiber bladder afferents contribute to bladder hyperactivity and incontinence in patients with neurogenic bladder dysfunction.

Intrastriatal transplantation of Sertoli cells may improve amphetamine-induced rotation and tyrosine hydroxylase immunoreactivity of the striatum in hemiparkinsonian rats

This study investigated survival and neurotrophic effects of Sertoli cells transplanted in the striatum of 6-hydroxydopamine (6-OHDA)-induced hemiparkinsonian rats. Primary cultures of Sertoli cells were established from 3-week old rats and characterized by associated marker, placental cadherin (P-cadherin). Two months after transplantation, amphetamine-induced rotations of rats transplanted with Sertoli cells were significantly lower than those of control rats. However, restoration of tyrosine hydroxylase (TH) immunoreactivity and Sertoli cells that expressed P-cadherin were only found in the striatum of the rat that showed full recovery from amphetamine-induced rotation 3 months after transplantation without immunosuppression. These results suggest that Sertoli cells transplanted in striatum of hemiparkinsonian rats may survive for at least 3 months, and improve amphetamine-induced rotation and restore TH immunoreactivity.

Synthetase recognition determinants of E. coli valine transfer RNA

We have studied the interactions between Escherichia coli tRNAVal and valyl-tRNA synthetase (ValRS) by enzymatic footprinting with nuclease S1 and ribonuclease V1, and by analysis of the aminoacylation kinetics of mutant tRNAVal transcripts. Valyl-tRNA synthetase specifically protects the anticodon loop, the 3' side of the stacked T-stem/acceptor-stem helix, and the 5' side of the anticodon stem of tRNAVal against cleavage by double- and single-strand-specific nucleases. Increased nuclease susceptibility at the ends of the anticodon- and T-stems in the tRNAVal.ValRS complex is indicative of enzyme-induced conformational changes in the tRNA. The most important synthetase recognition determinants are the middle and 3' anticodon nucleotides (A35 and C36, respectively); G20, in the variable pocket, and G45, in the tRNA central core, are minor recognition elements. The discriminator base, position 73, and the anticodon stem also are recognized by ValRS. Replacing wild-type A73 with G73 reduces the aminoacylation efficiency more than 40-fold. However, the C73 and U73 mutants remain good substrates for ValRS, suggesting that guanosine at position 73 acts as a negative determinant. The amino acid acceptor arm of tRNAVal contains no other synthetase recognition nucleotides, but regular A-type RNA helix geometry in the acceptor stem is essential [Liu, M., et al. (1997) Nucleic Acids Res. 25, 4883-4890]. In the anticodon stem, converting the U29:A41 base pair to C29:G41 reduces the aminoacylation efficiency 50-fold. This is apparently due to the rigidity of the anticodon stem caused by the presence of five consecutive C:G base pairs, since the A29:U41 mutant is readily aminoacylated. Identity switch experiments provide additional evidence for a role of the anticodon stem in synthetase recognition. The valine recognition determinants, A35, C36, A73, G20, G45, and a regular A-RNA acceptor helix are insufficient to transform E. coli tRNAPhe into an effective valine acceptor. Replacing the anticodon stem of tRNAPhe with that of tRNAVal, however, converts the tRNA into a good substrate for ValRS. These experiments confirm G45 as a minor ValRS recognition element.

Preferential recognition of zwitterionic dipeptides as transportable substrates by the high-affinity peptide transporter PEPT2

We investigated the interaction of rat PEPT2, a high-affinity peptide transporter, with neutral, anionic, and cationic dipeptides using electrophysiological approaches as well as tracer uptake methods. D-Phe-L-Gln (neutral), D-Phe-L-Glu (anionic), and D-Phe-L-Lys (cationic) were used as representative, non-hydrolyzable, dipeptides. All three dipeptides induced H+-dependent inward currents in Xenopus laevis oocytes heterologously expressing rat PEPT2. The H+:peptide stoichiometry was 1:1 in each case. A simultaneous measurement of radiolabeled dipeptide influx and charge transfer in the same oocyte indicated a transfer of one net positive charge into the oocyte per transfer of one peptide molecule irrespective of the charged nature of the peptide. We conclude that the zwitterionic peptides are preferentially recognized by PEPT2 as transportable substrates and that the proton/peptide stoichiometry is 1 for the transport process.

Clinical observations of erythema multiforme in children

Erythema multiforme (EM), a cutaneous or mucocutaneous disorder, occurs primarily in young adults. To evaluate the precipitating factors, clinical courses, and treatment of this disease in children, 30 cases aged from 1 month old to 15 years of age were studied retrospectively from Jan 1988 to Aug 1998. Twenty-three cases were diagnosed as minor type; the other 7 were of major type (Stevens-Johnson syndrome). Mycoplasma infection was identified in 4 patients, and adenovirus in one patient with EM minor. Cytomegalovirus was found in one EM major patient. Anticonvulsant administration before the skin lesions were recorded in 5 EM major patients and 2 EM minor patients. All cases received supportive treatment during admission. Besides, 6 of 7 patients with EM major, and 11 of 23 EM minor (Group A) received systemic corticosteroid at a dose equal to prednisolone 1-2 mg/kg/day for 3-14 days. One EM major patient and 11 patients with EM minor (Group B) received supportive care only. One EM minor patient with acute idiopathic thrombocytopenia purpura was treated with intravenous immunoglobulin. The mean duration of course of EM minor was 11.8 +/- 2.9 days, and it was 25.1 +/- 9.8 days for EM major. No mortality and no sequelae were noted. The average disease course and hospitalization time were not significantly different between Group A and B: (11.4 +/- 3.1 days vs 12.4 +/- 2.9 days, p = 0.45); (5.4 +/- 2.0 days vs 6.3 +/- 3.1 days, p = 0.47). This study demonstrated that infections, especially mycoplasma, and anticonvulsants play important roles in childhood EM. The skin lesions of EM minor subsided within 2 weeks, and EM major recovered completely within 6 weeks. Systemic corticosteroid may be beneficial to EM major, but probably is unnecessary for patients with EM minor.