Focal acidosis in the pre-Botzinger complex area of awake goats induces a mild tachypnea

There are widespread chemosensitive areas in the brain with varying effects on breathing. In the awake goat, microdialyzing (MD) 50% CO(2) at multiple sites within the medullary raphe increases pulmonary ventilation (Vi), blood pressure, heart rate, and metabolic rate (Vo(2)) (11), while MD in the rostral and caudal cerebellar fastigial nucleus has a stimulating and depressant effect, respectively, on these variables (17). In the anesthetized cat, the pre-Bötzinger complex (preBötzC), a hypothesized respiratory rhythm generator, increases phrenic nerve activity after an acetazolamide-induced acidosis (31, 32). To gain insight into the effects of focal acidosis (FA) within the preBötzC during physiological conditions, we tested the hypothesis that FA in the preBötzC during wakefulness would stimulate breathing, by increasing respiratory frequency (f). Microtubules were bilaterally implanted into the preBötzC of 10 goats. Unilateral MD of mock cerebral spinal fluid equilibrated with 6.4% CO(2) did not affect Vi, tidal volume (Vt), or f. Unilateral MD of 25 and 50% CO(2) significantly increased Vi and f by 10% (P < 0.05, n = 10, 17 trials), but Vt was unaffected. Bilateral MD of 6.4, 25, or 50% CO(2) did not significantly affect Vi, Vt, or f (P > 0.05, n = 6, 6 trials). MD of 80% CO(2) caused a 180% increase in f and severe disruptions in airflow (n = 2). MD of any level of CO(2) did not result in any significant changes in mean arterial blood pressure, heart rate, or Vo(2). Thus the data suggest that the preBötzC area is chemosensitive, but the responses to FA at this site are unique compared with other chemosensitive sites.

The cerebellar fastigial nucleus contributes to CO2-H+ ventilatory sensitivity in awake goats

The purpose of this study was to test the hypothesis that an intact cerebellar fastigial nucleus (CFN) is an important determinant of CO(2)-H(+) sensitivity during wakefulness. Bilateral, stainless steel microtubules were implanted into the CFN (N=9) for injection (0.5-10 microl) of the neurotoxin ibotenic acid. Two or more weeks after implantation of the microtubules, eupneic breathing and CO(2)-H(+) sensitivity did not differ significantly (P>0.10) from pre-implantation conditions. Injection of ibotenic acid (50 mM) did not significantly alter eupneic Pa(CO2) (P>0.10). The coefficient of variation of eupneic Pa(CO2) was 4.0+/-0.6 and 3.7+/-0.4% over the 2 weeks before and after the lesion, respectively. CO(2)-H(+) sensitivity expressed as inspired ventilation/Pa(CO2) decreased from 2.15+/-0.17 pre-lesion to 1.58+/-0.26 l/(min mmHg) 3-6 days post-lesion (P<0.02, -27%). There was no significant (P>0.10) recovery of sensitivity between 7 and 10 days post-lesion. The lesion also increased (P<0.05) the day-to-day variability of this index by nearly 100%. When CO(2) sensitivity was expressed as elevated inspired CO(2)/room air V (I), values at 7%, but not 3 and 5% inspired CO(2), were reduced and more variable (P<0.05) after the ibotenic acid injections. We conclude that during wakefulness, the CFN contributes relatively more to overall ventilatory drive at high relative to low levels of hypercapnia.

Lesions in the cerebellar fastigial nucleus have a small effect on the hyperpnea needed to meet the gas exchange requirements of submaximal exercise

The purpose of this study was to test the hypothesis that an intact cerebellar fastigial nucleus (CFN) is necessary for the hyperpnea to meet the gas exchange needs of submaximal exercise. Bilateral stainless steel microtubules were implanted in the cerebellum inside (n = 12) or outside (n = 2) the CFN for injection (0.5 to 10 microl) of the neurotoxin ibotenic acid. All goats had difficulty maintaining normal posture and walking for up to 1 mo after the implantation of the microtubules and again for hours or days after the neurotoxin was injected. Postmortem histology indicated there were 55% fewer living neurons (P < 0.001, n = 9, 3,720 +/- 553 vs. 1,670 +/- 192) in the CFN of the experimental goats compared with a control group of goats. As is typical for goats before implantation of the microtubules, the decrease in arterial Pco(2) from rest during mild and moderate treadmill exercise was 2.0 +/- 0.39 and 3.5 +/- 0.45 Torr, respectively. Implantation of the microtubules did not significantly change this exercise hyperventilation. However, neurotoxic lesioning with 10 mul ibotenic acid significantly (P < 0.05) attenuated the decrease in arterial Pco(2) by 1.3 and 2.8 Torr at the first and second workload, respectively. The modest attenuation of the exercise hypocapnia at both workloads in CFN-lesioned goats suggests that the CFN is part of the control system that enables the ventilatory response to meet the gas exchange requirements of submaximal exercise.

CO2/H+ chemoreceptors in the cerebellar fastigial nucleus do not uniformly affect breathing of awake goats

Our objective in this study was to test the hypothesis that focal acidosis (FA) in the cerebellar fastigial nucleus (CFN) of awake goats arising from global brain acidosis induced by increasing inspired CO2 will increase breathing. FA was created by reverse microdialysis of mock cerebral spinal fluid, equilibrated with 6.4, 25, 50, or 80% CO2 through chronically implanted microtubules (cannula). Dialysis with 6.4% CO2 had no significant effects on any physiological parameters. However, microdialysis at higher levels of CO2 increased pulmonary ventilation (V(I)) in one group of studies and decreased V(I) in a second group and the difference between the groups was significant (t = 9.16, P < 0.001). In one group of studies (n = 8), FA with 50 and 80% CO2 significantly increased (P < 0.05) Vi by 16 and 12%, respectively, and significantly increased (P < 0.05) heart rate by 13 and 9%, respectively. In contrast, in another group of studies (n = 6), FA with 25 and 50% CO2 significantly decreased (P < 0.05) Vi by 7 and 10%, respectively. In this group oxygen consumption was decreased during dialysis with 80% CO2. On the basis of histology, we estimate that the increased and decreased responses were associated with FA primarily in the rCFN and cCFN, respectively. We conclude that there are CO2/H+-sensitive neurons in the CFN that do not uniformly affect breathing. In addition, the significant changes in heart rate and oxygen consumption during FA indicate that the CFN can also influence non-respiratory-related control systems.

Carotid body denervation alters ventilatory responses to ibotenic acid injections or focal acidosis in the medullary raphe

Our aim was to determine the effects of carotid body denervation (CBD) on the ventilatory responses to focal acidosis and ibotenic acid (IA) injections into the medullary raphe area of awake, adult goats. Multiple microtubules were chronically implanted into the midline raphe area nuclei either before or after CBD. For up to 15 days after bilateral CBD, arterial PCO2 (PaCO2) (13.3 +/- 1.9 Torr) was increased (P < 0.001), and CO2 sensitivity (-53.0 +/- 6.4%) was decreased (P <0.001). Thereafter, resting PaCO2 and CO2 sensitivity returned (P <0.01) toward control, but PaCO2 remained elevated (4.8 +/- 1.9 Torr) and CO2 sensitivity reduced (-24.7 +/- 6.0%) > or =40 days after CBD. Focal acidosis (FA) at multiple medullary raphe area sites 23-44 days post-CBD with 50 or 80% CO(2) increased inspiratory flow (Vi), tidal volume (Vt), metabolic rate (VO2), and heart rate (HR) (P <0.05). The effects of FA with 50% CO2 after CBD did not differ from intact goats. However, CBD attenuated (P <0.05) the increase in Vi, Vt, and HR with 80% CO2, but it had no effect on the increase in VO2. Rostral but not caudal raphe area IA injections increased Vi, BP, and HR (P < 0.05), and these responses were accentuated (P <0.001) after CBD. CO2 sensitivity was attenuated (-20%; P <0.05) <7 days after IA injection, but thereafter it returned to prelesion values in CBD goats. We conclude the following: 1) the attenuated response to FA after CBD provides further evidence that the carotid bodies provide a tonic facilitory input into respiratory control centers, 2) the plasticity after CBD is not due to increased raphe chemoreceptor sensitivity, and 3) the "error-sensing" function of the carotid body blunts the effect of strong stimulation of the raphe.

Transient attenuation of CO2 sensitivity after neurotoxic lesions in the medullary raphe area of awake goats

The major objective of this study was to gain insight into whether under physiological conditions medullary raphe area neurons influence breathing through CO(2)/H(+) chemoreceptors and/or through a postulated, nonchemoreceptor modulatory influence. Microtubules were chronically implanted into the raphe of adult goats (n = 13), and breathing at rest (awake and asleep), breathing during exercise, as well as CO(2) sensitivity were assessed repeatedly before and after sequential injections of the neurotoxins saporin conjugated to substance P [SP-SAP; neurokinin-1 receptor (NK1R) specific] and ibotenic acid (IA; nonspecific glutamate receptor excitotoxin). In all goats, microtubule implantation alone resulted in altered breathing periods, manifested as central or obstructive apneas, and fractionated breathing. The frequency and characteristics of the altered breathing periods were not subsequently affected by injections of the neurotoxins (P > 0.05). Three to seven days after SP-SAP or subsequent IA injection, CO(2) sensitivity was reduced (P < 0.05) by 23.8 and 26.8%, respectively, but CO(2) sensitivity returned to preinjection control values >7 days postinjection. However, there was no hypoventilation at rest (awake, non-rapid eye movement sleep, or rapid eye movement sleep) or during exercise after these injections (P > 0.05). The neurotoxin injections resulted in neuronal death greater than three times that with microtubule implantation alone and reduced (P < 0.05) both tryptophan hydroxylase-expressing (36%) and NK1R-expressing (35%) neurons at the site of injection. We conclude that both NK1R- and glutamate receptor-expressing neurons in the medullary raphe nuclei influence CO(2) sensitivity apparently through CO(2)/H-expressing chemoreception, but the altered breathing periods appear unrelated to CO(2) chemoreception and thus are likely due to non-chemoreceptor-related neuromodulation of ventilatory control mechanisms.

Distribution of Indel lengths

Protein sequence alignment has become a widely used method in the study of newly sequenced proteins. Most sequence alignment methods use an affine gap penalty to assign scores to insertions and deletions. Although affine gap penalties represent the relative ease of extending a gap compared with initializing a gap, it is still an obvious oversimplification of the real processes that occur during sequence evolution. To improve the efficiency of sequence alignment methods and to obtain a better understanding of the process of sequence evolution, we wanted to find a more accurate model of insertions and deletions in homologous proteins. In this work, we extract the probability of a gap occurrence and the resulting gap length distribution in distantly related proteins (sequence identity < 25%) using alignments based on their common structures. We observe a distribution of gaps that can be fitted with a multiexponential with four distinct components. The results suggest new approaches to modeling insertions and deletions in sequence alignments.

Rat glutathione S-transferase M4-4: an isoenzyme with unique structural features including a redox-reactive cysteine-115 residue that forms mixed disulphides with glutathione

Although the existence of the rat glutathione S-transferase (GST) M4 (rGSTM4) gene has been known for some time, the corresponding protein has not as yet been purified from tissue. A recombinant rGSTM4-4 was thus expressed in Escherichia coli from a chemically synthesized rGSTM4 gene. The catalytic efficiency (k(cat)/K(m)) of rGSTM4-4 for the 1-chloro-2,4-dinitrobenzene (CDNB) conjugation reaction was 50-180-fold less than that of the well-characterized homologous rGSTM1-1, and the pH optimum for the same reaction was 8.5 for rGSTM4-4 as opposed to 6.5 for rGSTM1-1. Molecular-modelling studies predict that key substitutions in the helix alpha4 region of rGSTM4-4 account for this pK(a) difference. A notable structural feature of rGSTM4-4 is the Cys-115 residue in place of the Tyr-115 of other Mu-class GSTs. The thiol group of Cys-115 is redox-reactive and readily forms a mixed disulphide even with GSH; the S-glutathiolated form of the enzyme is catalytically active. A mutated rGSTM4-4 (C115Y) had 6-10-fold greater catalytic efficiency than the wild-type rGSTM4-4. Trp-45, a conserved residue among Mu-class GSTs, is essential in rGSTM4-4 for both enzyme activity and binding to glutathione affinity matrices. Antibodies directed against either the unique C-terminal undecapeptide or tridecapeptide of rGSTM4 reacted with rat and mouse liver GSTs to reveal an orthologous mouse GSTM4-4 present at low basal levels but which is inducible in mouse liver. This subclass of rodent Mu GSTs with redox-active Cys-115 residues could have specialized physiological functions in response to oxidative stress.

[Primary cutaneous CD30-positive anaplastic large cell lymphoma]

OBJECTIVE

To analyse the clinical manifestations, pathological and immunohistochemical features of 9 cases of primary cutaneous CD30-positive anaplastic large cell lymphoma (ALCL) in order to improve the criteria for its early and differential diagnosis.

METHODS

Histopathological method was used to study the morphological characteristics. Immunohistochemical stainings (SP or ABC method) for leukocyte common antigen (LCA), CD20, CD30, CD45RO, CD68, epithelium membrane antigen (EMA), cytokeratin (CK) and HMB45 were applied to the routine paraffin sections of all the 9 cases.

RESULTS

The 9 cases of primary cutaneous CD30-positive ALCL consisting of 6 males and 3 females, aged 31 to 84 years (mean 58.2 years). All patients presented with subcutaneous masses or papular eruptions on lower trunk and extremities. Histopathologically, the lesions were composed of numerous large round, oval or pleomorphic cells with abundant cytoplasm, amphophilic or basophilic, and large nucleus with distinct nucleolus. Mitosis was often observed. Multinucleated giant cells and Reed-Sternberg cells may be seen. The neoplastic cells displayed positive antigen markers for CD30 in 9 cases, 6 positive for CD45RO and 3 cases negative for both CD45RO and CD20. Two patients died of metastasis, 2 patients experienced recurrence and 5 patients still well during follow-up.

CONCLUSIONS

Primary cutaneous CD30-positive ALCL is a morphologically distinctive neoplasm with a comparatively favorable prognosis. This tumor can be differentiated from other malignant tumors on the basis of histopathologic features and positive CD30 which is of significance.

Noninvasive diagnosis of renal-allograft rejection by measurement of messenger RNA for perforin and granzyme B in urine

BACKGROUND

Acute rejection is a serious and frequent complication of renal transplantation, and its diagnosis is contingent on the invasive procedure of allograft biopsy. A noninvasive diagnostic test for rejection could improve the outcome of transplantation.

METHODS

We obtained 24 urine specimens from 22 renal-allograft recipients with a biopsy-confirmed episode of acute rejection and 127 samples from 63 recipients without evidence of acute rejection. RNA was isolated from the urinary cells. Messenger RNA (mRNA) encoding the cytotoxic proteins perforin and granzyme B and a constitutively expressed cyclophilin B gene were measured with the use of a competitive, quantitative polymerase chain reaction, and the level of expression was correlated with allograft status.

RESULTS

The log-transformed mean (+/-SE) levels of perforin mRNA and granzyme B mRNA, which encode cytotoxic proteins, but not the levels of constitutively expressed cyclophiiin B mRNA, were higher in the urinary cells from the 22 patients with a biopsy-confirmed episode of acute rejection than in the 63 recipients without an episode of acute rejection (perforin, 1.4+/-0.3 vs. -0.6+/-0.2 fg per microgram of total RNA; P<0.001; and granzyme B, 1.2+/-0.3 vs. -0.9+/-0.2 fg per microgram of total RNA; P<0.001). Analysis involving the receiver-operating-characteristic curve demonstrated that acute rejection can be predicted with a sensitivity of 83 percent and a specificity of 83 percent with the use of a cutoff value of 0.9 fg of perforin mRNA per microgram of total RNA, and with a sensitivity of 79 percent and a specificity of 77 percent with the use of a cutoff value of 0.4 fg of granzyme B mRNA per microgram of total RNA. Sequential urine samples were obtained from 37 patients during the first nine days after transplantation; and measurements of the levels of mRNA that encoded cytotoxic proteins identified those in whom acute rejection developed.

CONCLUSIONS

Measurement of mRNA encoding cytotoxic proteins in urinary cells offers a noninvasive means of diagnosing acute rejection of renal allografts.

[Changes of genomic density polymorphism and quantitative expression of complement receptor type 1 in patients with liver diseases]

OBJECTIVE

To study the changes of genomic density polymorphism and quantitative expression of complement receptor type 1 (CR1) on erythrocytes in patients with liver diseases.

METHODS

Polymerase chain reaction (PCR) and Hind III restriction enzyme digestion and the quantitative assay of erythrocytic CR1 were used.

RESULTS

The spot mutation rate (25.0% approximately 30.3%) of erythrocyte CR1 density gene in patients with liver diseases was not significantly different with that of healthy individuals (28.0%). The amount of erythrocytic CR1 in patients with liver diseases, except for those with normal liver function, was significantly lower than that of healthy individuals (t=10.44, P<0.0001). The quantitative expression of erythrocytic CR1 in decompensated cirrhosis was obviously lower than that of compensated cirrhosis (t=2.21, P<0.05).

CONCLUSION

Defective expression of CR1 in liver diseases is acquired through central and/or peripheral mechanisms. It is very important to study the quantitative expression in the evaluation of the development of liver diseases.

Optimization of a new score function for the detection of remote homologs

The growth in protein sequence data has placed a premium on ways to infer structure and function of the newly sequenced proteins. One of the most effective ways is to identify a homologous relationship with a protein about which more is known. While close evolutionary relationships can be confidently determined with standard methods, the difficulty increases as the relationships become more distant. All of these methods rely on some score function to measure sequence similarity. The choice of score function is especially critical for these distant relationships. We describe a new method of determining a score function, optimizing the ability to discriminate between homologs and non-homologs. We find that this new score function performs better than standard score functions for the identification of distant homologies.

Primary malignant melanoma arising from the base of the tongue

A rare case of malignant melanoma of the base of the tongue in a 65-year-old Japanese woman is described. The primary and metastatic tumors were treated by surgery, chemohormone and immunotherapy. There was no recurrence for 5 years after the initial diagnosis. Electron microscopy suggested that the melanosomes of the melanoma cells in the cervical lymph nodes were less mature than those in the primary melanoma cells; melanosome immaturity was consistent with a more aggressive quality.

Multiple origins of Tibetan Y chromosomes

The genetic origin of Tibetans was investigated using Y chromosome markers. A total of three populations were studied, two from central Tibet speaking central Tibetan and one from Yunnan speaking Kham. Two dominant paternal lineages (>80%) were identified in all three populations with one possibly from central Asia (YAP+) and the other from east Asia (M122C). We conclude that Tibetan Y chromosomes may have been derived from two different gene pools, given the virtual absence of M122C in central Asia and YAP+ in east Asia, with drift an unlikely mechanism accounting for these observations.

[Study on the synergistic coloration of tin (II) with pyrocatechol violet and rhodamine B and its application]

In the presence of PVA, a sensitive color reaction of tin (I ) on pyrocatechol violet and rhodamine B has been studied. In a NaAc-HAc (pH = 5.0) medium, tin(II) ions form an ions-associate complex with pyrocatechol violet and rhodamine B. The composition of the complex is Sn (II): PV : RhB = 1 : 2: 4. The maximum absorption of the ions-associate complex is at 560 nm with an apparent molar absorptivity of 1.18 x 10(5) L x mol(-1) x cm(-1). Beer's law is obeyed in the range of 0-15 microg/25 mL of tin. The method is highly selective and has been applied to the determination of trace tin in some objects with satisfactory results.

A prourokinase-RGDS chimera : Construction, expression and characterization

A tetrapeptide, RGDS, was inserted into proUK kringle domain G118-L119 by the construction of a mutant proUK-RGDS gene. The gene was expressed in the baculovirus expression system. Immunoaffinity chromatography was used to purify the chimera and protein with purity over 90% was achieved. The chimera was tested for its platelet membrane binding function and showed a calcium-dependent platelet binding activity. Amidolytic activity of the chimera was tested. The result indicated that specific amidolytic activity of plasmin activated chimera was 62 000 IU/mg, comparable to the previously reported 65 355 IU/mg of plasmin activated natural proUK([1]). Activation of plasminogen by the chimera after plasmin treatment followed Michieal-Menten kinetics, and the Km was 0.97 mumol/L, which was also comparable to 1.64 mumol/L of native urokinase. The chimera also showed intensive ability to inhibit platelet aggregationin vitro. These results indicate that this chimera might be useful as a bifunctional thrombolytic agent.

Paracortical hyperplasia of superficial lymph nodes in a new mutant strain of hairless rats (ISh): a lesion similar to human dermatopathic lymphadenopathy

The dermal histology and the regional draining superficial lymph node of a new mutant strain of hairless rats (ISh) were investigated. The homozygote ISh rat was characterized as having naked and wrinkled skin. The comedo-like cysts in the skin resembled human acne and vulgaris. Histopathologically, many Langerhans' cells positive for anti-protein kinase C type II antibody (PKC-II) were recognized in the epidermis. The superficial lymph nodes were significantly larger than those of the heterozygote. The paracortex of these lymph nodes was expanded and the number of Langerhans' cells mainly increased in these areas. These lymph node lesions were similar to those of human dermatopathic lymphadenopathy. The ISh rats should be a very useful animal model for studying dermatopathic lymphadenopathy in humans. Furthermore, they may be a valuable animal model for investigating the mechanisms of not only maturation, movement and migration of Langerhans' cells, but also of their function for antigen presentation.