Focal infections due to non-typhi Salmonella in patients with AIDS: report of 10 cases and review

Bacteremia due to non-typhi Salmonella is frequent in human immunodeficiency virus (HIV)-infected patients; however, focal complications rarely have been reported. Ten of 38 HIV-infected patients (26.3%) with salmonellosis documented over a period of 9 years had focal suppurative complications; only 19 (3.9%) of 490 adults without HIV infection who were seen during the same period had focal complications (P = .001). Infections of the urinary tract, lungs, and soft tissue, followed by arthritis, endocarditis, and meningitis were most frequently seen. Although salmonellosis occasionally heralded HIV infection, most patients were severely immunocompromised and had CD4 cell counts of <100/mm3. The mortality rate was 50%, equivalent to that observed among patients with other immunosuppressive disorders (52.6%). Major emphasis must be put on intensive therapy for salmonella bacteremia and prevention of its complications.

Bone marrow biopsy in the diagnosis of fever of unknown origin in patients with acquired immunodeficiency syndrome

BACKGROUND

Fever is commonly observed in patients with human immunodeficiency virus (HIV) disease and frequently eludes diagnosis. The role of bone marrow biopsy in the diagnosis of fever of unknown origin in patients infected with HIV remains controversial.

PATIENTS AND METHODS

One hundred twenty-three consecutive patients with 137 episodes of fever lasting 10 or more days without diagnosis after 1 week of hospitalization were evaluated by bone marrow biopsy.

RESULTS

Overall, a specific diagnosis was achieved in 52 episodes by means of culture and histopathological examination (diagnostic yield, 37.9%). Three types of disease were found: mycobacterial infections (n = 36, 69% of documented episodes), including 18 patients with disseminated tuberculosis and 14 with Mycobacterium avium-intracellulare complex infections; non-Hodgkin lymphomas (n = 12, 23%); and visceral leishmaniasis (n = 4, 8%). Although bone marrow cultures were more sensitive than microscopic examination with special stains for the diagnosis of mycobacterial infections, the pathological examination of bone marrow led to a more rapid diagnosis of disease. In addition, the histopathological examination of bone marrow alone led to the diagnosis of a specific condition in 43 episodes (31.3% of all episodes).

CONCLUSIONS

Bone marrow biopsy is a useful procedure for the diagnosis of fever in patients with advanced HIV disease, particularly in areas where tuberculosis and leishmaniasis are prevalent. Involvement of the marrow may be the first indication of the existence of extranodal non-Hodgkin lymphoma. For Mycobacterium avium-intracellulare complex infection, blood cultures were more sensitive than bone marrow biopsy.

Regulation of mevalonate 5-pyrophosphate decarboxylase in HeLa cells. Inhibition of enzymatic protein synthesis by serum lipoproteins

Mevalonate 5-pyrophosphate decarboxylase (EC 4.1.1.33) has been considered as a secondary site of regulation of cholesterogenesis. Because of this, we have studied the regulation of decarboxylase in HeLa cells by serum lipoproteins in the cell culture medium. A first group of experiments was performed with cells grown in Eagle's medium with 10% foetal calf serum. The specific activity of decarboxylase was increased when whole foetal calf serum was replaced with lipoprotein-poor serum. This increase was clearly reduced in the presence of cycloheximide. Addition of serum lipoproteins to a medium containing lipoprotein-poor serum led to a clear decrease in the decarboxylase activity. An identical decrease was observed after the addition of lipoproteins alone or in combination with cycloheximide. These results suggest for the first time that the effect of serum lipoproteins on decarboxylase activity should be a decrease in the rate of enzymatic protein synthesis, and corroborate the important role of reactions other than those catalysed by 3-hydroxy-3-methylglutaryl-CoA reductase in the regulation of cholesterogenesis.

[Bacteremia caused by group A and B beta-hemolytic Streptococcus in adults]

In order to know the epidemiological, clinical and evolutive characteristics of bacteriemia caused by beta-hemolytic streptococci groups A and B, a retrospective investigation was undertaken of 48 bacteremic episodes observed in adult patients for 10 years (1985-1994). Twenty-two episodes were caused by Group A beta-hemolytic streptococci (GAS) and 26 by Group B beta-hemolytic streptococci (GBS). Patients with GAS bacteremia (GASB) had a lower mean age than patients with GBS bacteremia (GBSB) (p = 0.03). Infection with immunodeficiency virus was more common in patients with GASB than in patients with GBSBA (27 and 4%, respectively; p = 0.04); in contrast, diabetes mellitus was more common in patients with GBSB than in patients with GASB (27 and 5%, respectively) (p = 0.04). Nine (41%) patients with GBSB were i.v. drug abusers; nevertheless, none of the subjects with GBSB were i.v. drug abusers (p < 0.001). The proportion of bacteremia without demonstrable source due to GBS (41%) was significantly higher than that due to GAS (9%) (p = 0.02). Five (23%) patients with GASB and other five (20%) patients with GBSB had fatal outcomes, but only in two (9%) and three (12%) cases, respectively, was death directly attributed to bacteremia. In conclusion, bacteremias caused by GAS and GBS have different epidemiological characteristics but similar prognosis.

Wolff-Parkinson-White syndrome presenting as the permanent form of junctional reciprocating tachycardia

The substrate of the permanent form of junctional reciprocating tachycardia is an accessory pathway with no spontaneous anterograde conduction, usually located in the posteroseptal area. We report a case of this type of tachycardia with overt anterograde ventricular preexcitation. Electrophysiologic study confirmed that tachycardia was due to an accessory pathway with long retrograde conduction time; electrophysiologic findings suggested longitudinal dissociation of the accessory pathway. Radiofrequency application at the coronary sinus os resulted in disappearance of preexcitation and cure of the tachycardia.

Mechanisms of entrainment of human common flutter studied with multiple endocardial recordings

BACKGROUND

The mechanisms of common atrial flutter entrainment have not been directly studied in humans.

METHODS AND RESULTS

Endocardial mapping in six cases of common flutter showed large right atrial (RA) reentry circuits. Activation was craniocaudal in the anterolateral right atrium and caudocranial in the septum. The inferior vena cava-tricuspid isthmus (IVC-TV) closed the circuit. The high right atrium was paced at progressively shorter cycle lengths (CLs) in all, and the IVC-TV was paced in three cases. We recorded six to eight simultaneous RA electrograms from septum and anterior wall. Transient entrainment was recognized from all sites by capture of all electrograms at two or more paced CLs, with total or partial preservation of baseline flutter sequence and return to baseline after pacing. Antidromic circuit penetration was documented in five cases during high RA pacing and in one with IVC-TV pacing. Short CLs induced orthodromic conduction delays that resulted in a postpacing pause longer than basal flutter CL. ECG fusion with high RA pacing correlated poorly with antidromic septal penetration. This was related to overlap of orthodromic septal activation with anterior wall activation of the following cycle. Pacing disorganized flutter into a brief irregular rapid rhythm in two cases and atrial fibrillation in one case. In two cases, complete antidromic septal penetration led to sudden flutter interruption, and in another case it led to circuit inversion.

CONCLUSIONS

Direct recordings confirm orthodromic and antidromic penetration of flutter circuits by high and low RA pacing. Short CLs modify the circuit. Disorganization is the most common mode of flutter interruption.

Spontaneous activity and responses to sensory stimulation in ventrobasal thalamic neurons in the rat: an in vivo intracellular recording and staining study

Spontaneous activity and responses to sensory stimulation in ventrobasal (VB) thalamic neurons were studied in barbiturate-anesthetized rats through intracellular recordings. The recordings were carried out with micropipettes filled with K acetate KCl plus horseradish peroxidase (HRP), our KCl plus biocytin. Two types of spontaneous depolarizing events were observed: fast potentials (FPs), characterized by a low amplitude (5.3 +/- 1.8 mV [mean and standard deviation]), a fast rising slope (1.15 +/- 0.19 msec), and a short duration (8.47 +/- 0.89 msec); and slow potentials (SPs), characterized by a larger and more variable amplitude (9.1 +/- 5.6 mV) and a longer duration (62.5 +/- 27.2 msec), with a slower rising slope (26.2 +/- 6.4 msec). The potential changes elicited by sensory stimuli delivered manually were similar to those elicited by electronically gated short air jets to the receptive fields. FPs were evoked by sensory stimulation in 62.7% of the recorded neurons, and SPs in the remaining 37.3%. Both types of events could occur spontaneously in the same neuron, but only one of them was triggered by stimulation of the receptive field. Five neurons that were successfully stained with either HRP or biocytin were studied in detail. All were medium-sized stellate cells, with spine-like appendages sparsely distributed along slender radiating dendrites. The axons took a rostrolateral course across the VB, and all but one left one or two thin collaterals in the reticular thalamic nucleus. No overt morphological differences were observed between VB neurons that responded with FPS or SPs to sensory stimulation.

Purification of a soluble casein kinase II from Dictyostelium discoideum lacking the beta subunit: regulation during proliferation and differentiation

A type II casein kinase has been purified from the soluble fraction of Dictyostelium discoideum vegetative cells. The enzyme has been purified 370 fold and behaves catalytically as casein kinase type II, in the sense that it utilizes GTP as well as ATP as phosphoryl donors, it is inhibited by low heparin concentrations and phosphorylates a specific peptide for CK II. It is a tetramer of 38 kDa-subunits with catalytic activity and ability to autophosphorylate in vitro. The comparison of this activity with the nuclear enzyme previously purified from the same organism indicates that both have the same molecular structure. Both enzymes have antigenic determinants in common with casein kinase II from bovine thymus, suggesting a high degree of conservation during evolution. Studies on the activity of this enzyme during early differentiation, and in the transition from quiescence to proliferation shows an increase in specific activity suggesting a crucial role for the enzyme in this organism.

Morphological and quantitative study of multinucleated bodies appearing in rat seminiferous tubules after bilateral caput epididymectomy

Adult Wistar rats were bilaterally caput epididymectomized and the effects on testicular germinal epithelium and formation of multinucleated bodies were studied and quantified at 2, 4, 7, 14, 21, and 28 days after surgery. Sham-operated and bilaterally efferentectomized animals served as controls. No alterations were found in sham-operated animals. Efferentectomized animals showed a progressive alteration of the seminiferous tubule epithelium and a (very occasional) presence of multinucleated bodies. Epididymectomized animals presented a progressive degeneration of the germinal epithelium, which was almost complete at 28 days. This epithelial degeneration was accompanied by the formation of multinucleated bodies from germinal cells, whose number and characteristics varied with the experimental interval. The multinucleated bodies described here resemble the multinucleated cells mentioned by other authors. They do not seem to be cellular; instead, they appear to be debris, since electron microscopic observations do not reveal a plasma membrane.

Frequency potentiation in granule cells in vivo at theta frequency perforant path stimulation

The effect of frequency potentiation on the postsynaptic potential in granule cells was studied stimulating the perforant path in curarized and urethanized rats. At stimulation frequencies between 2.0-5.0 Hz, synaptic efficacy in eliciting an orthodromic action potential increased despite the hyperpolarization of the transmembrane potential. The excitatory postsynaptic potential (EPSP) slope and duration also increased while the inhibitory postsynaptic potential (IPSP) was reduced. Stimulation frequencies greater than 5.0 Hz produced similar changes in the transmembrane potential and EPSP-IPSP sequence, but they did not increase synaptic efficacy. The frequency potentiation at frequencies into the theta band suggest that this potentiation participates in theta rhythm genesis in this structure which, in turn, suggests that the fascia dentata could work as a band-pass filter. In 12.5% of cases postpotentiation was also observed.

Synaptic contributions to theta rhythm genesis in rat CA1-CA3 hippocampal pyramidal neurons in vivo

The effects of intracellular Cl- diffusion and hyperpolarizing current pulses on inhibitory postsynaptic potentials (IPSPs) and the transmembrane theta rhythm of CA1-CA3 pyramidal neurons were tested in urethanized and curarized rats. Cl- diffusion and hyperpolarizing currents decreased the amplitude of IPSPs evoked by fornix stimulation without modifying the theta rhythm amplitude and phase. The membrane conductance was typically 22-46% higher at the positive than negative intracellular theta peaks. Results indicate that in curarized rats excitatory postsynaptic potentials were the main components of intracellular theta without an important participation of IPSPs in theta rhythm genesis.

Uptake of rhodamine 6GO into a specific zone of the mouse epididymis

Doses (2.5 mg/kg) of rhodamine 6GO were given subcutaneously to five Charles-Rivel mice. After 15 minutes the testis and epididymis were observed with a fluoroscope and a fluorescent microscope which showed that rhodamine 6GO was present in a rhodamine-fluorescent zone (RF-zone) of the caput epididymidis. In this RF-zone, the fluorochrome was localised in the epithelial cells of the epididymal duct but not in the lumen nor the vascular system. At the edge of the RF-zone a wide band of connective tissue was present; the epithelium of the epididymal duct in this zone was higher and its tubular diameter greater than in the rest of the epididymal duct and spermatozoa were usually not present in the lumen. A possible role played by the epididymis in the endocrine control of the testicular function is suggested.

Testicular changes in adult rat following bilateral partial (caput) epididymectomy

Adult Wistar rats were either partial (caput) and bilaterally epididymectomized or bilaterally efferentectomized, as controls of duct obstruction. The effects on testicular germinal epithelium were studied at 7, 9, 11, 13, 15, 17, 19, 21, 23 and 25 days after surgery. No abnormalities were detected in sham-operated animals. Epididymectomized animals showed different levels of alterations with progressive disruption of the seminiferous epithelium, emergence of multinucleated bodies and some tubules obliterated by degenerated cells and cellular debris. Half way through the experiment there were tubules lacking their epithelia, as well as the Sertoli cells. On the 25th day degeneration was so important that is affected not only the epithelium (missing in almost all tubules) but also the tubular morphology. Eventually efferentectomized animals showed a progressive alteration, but its level was much lower than that observed after partial epididymectomy, indicating a possible specific function of the caput epididymidis in the control of testicular function.

In vivo electrophysiological analysis of lucifer yellow-coupled hippocampal pyramids

Small transient all-or-none depolarizations (also termed in the literature fast prepotentials, spikelets, pseudospikes, d-spikes, or short latency depolarizations) and their association with lucifer yellow (LY) dye-coupling were analyzed in CA1-CA3 hippocampal pyramidal cells in urethane anesthetized rats. It was found that (a) 15 of the 24 LY-injected pyramidal neurons (63%) showed dye-coupling; (b) spontaneous, anti- and orthodromically evoked spikelets (3-7 ms in duration; 3- to 12-mV peak) were recorded in 40 of 95 cells (42%); (c) there was a significantly higher probability of dye-coupled neurons with spikelets and of uncoupled ones without spikelets; (d) spikelet waveform and amplitude were unaffected by spontaneous or imposed polarizations; (e) large hyperpolarizations could reduce the rate and even prevent spikelets; and (f) spikelets could precede or follow spikes, the latter were more frequent with large depolarizations. Electrophysiological findings, and the association of dye-coupling and spikelets, suggest strongly that at least some spikelets are coupling potentials. This implies that pyramidal cells may be electronically coupled under physiological conditions.

In vivo intracellular analysis of rat dentate granule cells

In vivo intracellular recordings and dentate EEG were obtained in urethanized-curarized rats. Granule cells (GCs) were identified by antidromic activation as well as by intracellular staining with Lucifer yellow (LY). GCs fired spikes which, in 43.6% of the cases, had brief post-hyperpolarization. Slow spikes were recorded at hyperpolarized levels during the rebound of hyperpolarizing pulses or during inhibitory postsynaptic potentials (IPSPs). Medial septal nucleus or perforant pathway stimulation evoked an excitatory postsynaptic potential (EPSP)-IPSP sequence. During theta (theta) rhythm, the membrane potential of 80.3% of the GCs showed rhythmic sine-like waves of up to 15 mV at a theta frequency which were phase-locked with extracellular theta. GCs were classified into 3 types: type 1 (67.1%) showed intracellular theta and rhythmic firing; type 2 (13.2%) revealed intracellular theta and random firing, but spikes tended to occur at a preferred phase of the dentate theta; and type 3 (19.7%) had neither intracellular theta nor rhythmic firing. Intracellular theta amplitude was wider during injection of the hyperpolarizing current and narrower during depolarizing ones, indicating that rhythmic EPSPs contribute to theta genesis. Intracellular theta was unaffected by Cl- or Cs+ diffusion, suggesting that IPSP is not essential to theta genesis.

A comparison of the effects of bilateral efferent duct ligation and of partial epididymectomy on the testes of rats

Testis weight as a percentage of body weight did not change following bilateral ligation of the efferent ducts (EDL) close to the epididymis, whereas following removal of part of the epididymis between the site of ligation and a point close to the junction between the caput and corpus (PCE), testis weight first rose linearly until Day 4 and then showed an exponential decrease between Days 4 and 28. After EDL, the perimeter of the seminiferous tubules rose for the first 7 days and then remained elevated, whereas after PCE, there was a linear decrease between Days 4 and 28. Following EDL, the percentage of altered and degenerated tubular cross-sections rose to about 30% and 10%, respectively, during the first 7 days after operation and then remained constant; after PCE, the percentage of altered tubules reached a maximum of 54% by 4 days and then fell, whereas the percentage of degenerated tubules continued to rise to 95% by 28 days. It would appear that all the effects of removal of a portion of the epididymis cannot be explained by blockage of the excurrent ducts, and a specific endocrine effect of the epididymis on the testis is proposed.

[Cardiac fulguration. A healing treatment for intranodal re-entry tachycardias refractory to medication]

Six patients underwent fulguration of the AV junction for typical paroxysmal intranodal reentry tachycardias, refractory to medical treatment. Unipolar cathodic discharges at distal electrode were administered against an external plate. Bipolar His and atrial deflections showed mean values of 0.16 and 0.54 mv, respectively. Mean energy used was 233 J (range 50-750), with a mean number of 1.6 (range 1-3) discharges per patient. Complete AV block was achieved, but conduction reappeared in all, within a mean of 30 minutes. Electrophysiologic evaluation was assessed 3-8 days after ablation. Intranodal reentry tachycardias could not be initiated in any patient. Retrograde conduction was abolished in 3 patients, and in three it was slow and decremental. First degree AV block, with intranodal delay was diagnosed in 4 with a mean AH interval of 237 msec (range 190-300). Mean rate for appearance of Wenckebach AV block was 154 b/m. None of the patients required permanent pacing. Mean follow-up of the patients was 6.8 months. One of the patients required a new ablation for reappearance of intranodal tachycardia and CAVB was achieved in the second ablation. The other five remain asymptomatic. Intranodal reentry tachycardias can be cured by fulguration. Less energy and less discharges should be administered to abolish functional dissociation of the AV node, without complete interruption of anterograde conduction.

[Nephrotoxicity of gentamicin and netilmicin in the rat. Quantification and qualification of glomeruli]

The application via i.v. jugular, in rats, of two fluorochromes (rhodamine 6GO and phosphine 3R) with a 10 min interval, allows the direct observation of nephronal corpuscles using an epifluorescent microscopical technique, as well as their eventual quantification and qualification into normal or semifunctional corpuscles. In rats previously treated by i.p. injection of gentamicin or netilmycin a decrease of the active nephronal population as well as an increase of the percentage of semifunctionality has been noticed.

[Hepatic and renal changes in albino rats caused by the administration of chromium (VI) in drinking water]

The effects of sodium chromate administered in drinking water on liver and kidney of albino rats have been studied, through investigation of histological alterations and monitoring changes on serum urea levels and transaminases (GOT and GPT). Measurements have been done after 4, 8 and 12 weeks of treatment. The liquid intake of treated animals decreases with time. The amount of water drunk by treated rats is 1/2 of that drink by controls after 12 weeks. The histological alterations in liver and kidney are similar to those described elsewhere. Serum urea level is always higher in treated animals than in controls. GOT levels are similar in both treated and control rats, although always higher in the treated ones. GPT levels increase significantly after 12 weeks of treatment.

Intracellular theta-rhythm generation in identified hippocampal pyramids

The hippocampal EEG and the transmembrane potential of CA1-CA3 hippocampal pyramids were recorded in curarized and urethanized rats. Pyramids were identified by antidromic driving and intracellular staining with Lucifer yellow. During theta-rhythm most pyramids showed 10-20 mV sustained depolarizations and potential oscillations either consisting of 5-10 mV smooth sine-like waves or slow spikes of up to 60 mV. Fast Na+ and slow, probably Ca2+-mediated, spikes were triggered by depolarizing pulses or spontaneously. Depolarizations greater than 15 mV triggered rhythmic slow spikes at theta-frequency, but if less than 15 mV, slow spikes were irregular and at lower rates. With depolarizations of less than 10 mV, no slow spikes were triggered. Sine-like intracellular theta-wave amplitudes increased with hyper- and decreased with depolarizing pulses, showing the behavior of rhythmic EPSPs. Periodic fast spike bursts were theta-correlated. Cells with intracellular theta could either fire periodic fast spike bursts or at random, but always at a preferred phase of the theta-wave. Slow spikes were generated above a potential threshold by a slow depolarization and driven by periodic EPSPs. Intracellular theta is the reflection of EPSPs and of slow spikes; the oscillatory phenomena are not exclusively generated, as previously hypothesized, by network properties which may, however, contribute as tuning and modulatory elements. The determining events in intracellular theta-generation are the intrinsic biophysical characteristics of the pyramidal neuron membrane.

Oxygen uptake and gill morphological alterations in Procambarus clarkii (Girard) after sublethal exposure to lead

The effects of sublethal lead concentrations on the oxygen uptake in whole animals and excised gill of Procambarus clarkii, as well as the gill morphological alterations, were investigated. Oxygen uptake rates of whole crayfish showed a great variability and decreased as the lead concentration increased. Significant differences were not found (ANOVA, P greater than 0.05). Oxygen consumption of excised gills decreased significantly as the lead concentration increased (P less than 0.01). Macroscopic and microscopic observations of the gill filaments of crayfish treated with 200 mg Pb/l indicated a general disorganization. The filaments showed the apices rounded and they appeared grossly blackened.