Path Planning and Motion Control of Indoor Mobile Robot under Exploration-Based SLAM (e-SLAM)

Indoor mobile robot (IMR) motion control for e-SLAM techniques with limited sensors, i.e., only LiDAR, is proposed in this research. The path was initially generated from simple floor plans constructed by the IMR exploration. The path planning starts from the vertices which can be traveled through, proceeds to the velocity planning on both cornering and linear motion, and reaches the interpolated discrete points joining the vertices. The IMR recognizes its location and environment gradually from the LiDAR data. The study imposes the upper rings of the LiDAR image to perform localization while the lower rings are for obstacle detection. The IMR must travel through a series of featured vertices and perform the path planning further generating an integrated LiDAR image. A considerable challenge is that the LiDAR data are the only source to be compared with the path planned according to the floor map. Certain changes still need to be adapted into, for example, the distance precision with relevance to the floor map and the IMR deviation in order to avoid obstacles on the path. The LiDAR setting and IMR speed regulation account for a critical issue. The study contributed to integrating a step-by-step procedure of implementing path planning and motion control using solely the LiDAR data along with the integration of various pieces of software. The control strategy is thus improved while experimenting with various proportional control gains for position, orientation, and velocity of the LiDAR in the IMR.

Effectiveness of transperitoneal and trans-retroperitoneal laparoscopic adrenalectomy versus open adrenalectomy

PURPOSE

This study compared the effectiveness of laparoscopic adrenalectomy, using either a transperitoneal or trans-retroperitoneal approach, with that of open adrenalectomy in patients with benign adrenal tumors.

METHODS

From February 1995 to April 2000, laparoscopic adrenalectomy was performed on 31 patients with adrenal tumors, including 16 aldosteronomas, 10 Cushing's adenomas, three nonfunctioning tumors, and two pheochromocytomas. A lateral trans-retroperitoneal approach was used for the first 16 patients and a lateral transperitoneal approach was used for the last 15 patients. Twenty-one patients who received open adrenalectomy during the same period served as a control group. Comparisons were made between laparoscopy and open groups, and between transperitoneal and trans-retroperitoneal groups.

RESULTS

Conversion to open adrenalectomy was necessary in two cases--both in the trans-retroperitoneal group during the first 2 years of the study period. No other intraoperative complications occurred and blood transfusion was not used. Compared with the open group, the laparoscopic group had less blood loss (71 vs 124 mL), resumed oral feeding earlier (28 vs 60 hr), required less postoperative narcotics (45 vs 120 mg meperidine), and had shorter postoperative hospital stays (4.9 vs 7.6 days) (all p < 0.05). The mean operative time was longer in the laparoscopic group (203 vs 123 min, p < 0.001). There were no significant differences between the transperitoneal and trans-retroperitoneal laparoscopy groups in any of the studied parameters, except that the operative time was longer in the trans-retroperitoneal laparoscopy group (244 vs 166 minutes, p < 0.01).

CONCLUSIONS

Decreased blood loss, less postoperative pain, earlier resumption of oral feeding, and shorter hospital stays were achieved in patients undergoing laparoscopic adrenalectomy. These findings indicate that laparoscopic adrenalectomy is the treatment of choice for benign adrenal tumors. The transperitoneal approach yielded shorter operative time than the trans-retroperitoneal approach, because it offered a clearer view and familiar landmarks.

Reaction competition in the fragmentation of protonated dipeptides

A major low-energy fragmentation reaction of many protonated dipeptides involves cleavage of the amide bond resulting in formation of either the y(1)" ion or the a(1) ion. For a series of protonated dipeptides H-Val-Xxx-OH it is observed that log(y(1)"/a(1)) is a linear function of the proton affinity of the variable C-terminal amino acid. For the series of protonated dipeptides H-Xxx-Phe-OH log(a(1)/y(1)") gives a poor correlation with the proton affinity or gas-phase basicity of H-Xxx-OH. However, a good limited correlation of log(a(1)/y(1)") with the Taft-Topsom sigma(alpha) for the alkyl group is observed when Xxx is an aliphatic amino acid. It is proposed that fragmentation occurs by initial formation of a proton-bound complex of an aziridinone and an amino acid which may fragment to form either a protonated amino acid (y(1)") or an N-protonated aziridinone with the corresponding neutrals being an aziridinone and an amino acid. Ab initio calculations show that the N-protonated aziridinone is unstable and fragments by loss of CO to form the a(1) immonium ion. However, the proton-bound complex of an aziridinone and an amine base is a stable species which exists in a potential well. Copyright 2000 John Wiley & Sons, Ltd.

The role of ganglioside GM3 in the modulation of conformation and activity of sarcoplasmic reticulum Ca(2+)-ATPase

Rabbit sarcoplasmic reticulum does contain trace amounts of gangliosides, and the main species is GM3. Incorporation of GM3 into the SR vesicles or addition of it to the soybean phospholipid used for reconstitution of proteoliposomes obviously increased ATP hydrolysis, as well as, Ca2+ uptake activity of sarcoplasmic reticulum Ca(2+)-ATPase. Conformation changes of Ca(2+)-ATPase induced by GM3 were also observed by circular dichroism, intrinsic fluorescence and fluorescence quenching measurements.

5-Lipoxygenase products are necessary for ovalbumin-induced airway responsiveness in mice

To determine the role of 5-lipoxygenase products in the development of airway reactivity that follows antigen exposure, we sensitized mice by intraperitoneal injection of ovalbumin and aluminum hydroxide and serial exposure to aerosols of ovalbumin. Mice lacking a functioning 5-lipoxygenase enzyme were produced by targeted gene disruption. They and their wild-type controls had measurements of lung resistance (RL) made in response to intravenous methacholine; bronchoalveolar lavage fluid cell counts and serum immunoglobulin concentrations were also measured. Wild-type mice developed striking increases in cholinergic responsiveness; 5-lipoxygenase-deficient mice manifested minimal alterations in methacholine responsiveness (RL at the highest methacholine dose was 9.9 +/- 2.4 cmH2O.ml-1.s-1 under control conditions vs. 27.6 +/- 4.6 cmH2O.ml-1.s-1 after ovalbumin in wild-type mice; 5.9 +/- 0.9 vs. 7.01 +/- 2.2 cmH2O.ml-1.s-1 in 5-lipoxygenase-deficient mice). Ovalbumin provoked airway eosinophilia and increased immunoglobulins in wild-type mice, which were present to a significantly lesser degree in 5-lipoxygenase-deficient mice. We conclude that 5-lipoxygenase products are essential for the production of nonspecific airway reactivity in mice and suggest that 5-lipoxygenase products may be important in immunoglobulin formation.

Se-mediated domain-domain communication in band 3 of human erythrocytes

Na2SeO3 could affect the anion flux of Band 3 of inside-out erythrocyte membrane vesicles (IOVs). Such effect was believed to be based on the interaction of SH groups of Band 3 with Na2SeO3. This effect could be eliminated when the cytoplasmic domain of Band 3 was proteolytically removed by trypsin. This suggested that SH groups in the cytoplasmic domain were involved in such interaction. Measurement of the pH dependence of intrinsic fluorescence intensity provided evidence that conformational changes of Band 3 occurred as a consequence of interaction with selenite. KI quenching of intrinsic fluorescence of Band 3 could also show that there was a conformational change in the cytoplasmic domain of Band 3 after reaction with Na2SeO3. Such conformational change in turn could be transmitted to the membrane domain of Band 3 monitored by quenching of intrinsic fluorescence of Band 3 using hypocrellin B (HB) (a photosensitive pigment obtained from a parasitic fungus growing in Yunnan, China). It is suggested that the cytoplasmic domain of Band 3 is not necessary for its anion flux, but is essential for the regulation (e.g., by Se) of its active site located at the membrane domain, and hence, it may provide evidence of communication between the cytoplasmic domain and the membrane domain of Band 3.

Transmembrane Ca2+ gradient is essential for high anion transport activity of human erythrocytes

The role of a transmembrane Ca2+ gradient in anion transport by Band 3 of human resealed erythrocyte ghosts has been studied. The results show that a transmembrane Ca2+ gradient is essential for the conformation of erythrocyte Band 3 with higher anion transport activity. The dissipation of the transmembrane Ca2+ gradient by the ionophore A23187 inhibits the anion transport activity. The extent of this inhibition approaches 90% as the Ca2+ concentration on both sides of the ghost membrane is increased to 1.0 mM and half-maximum inhibitions is observed at 0.25 mM Ca2+. Addition of ATP (0.4 mM) to the resealing medium can partly reestablish the transmembrane Ca2+ gradient by activation of Ca(2+)-ATPase and alleviate the inhibition to some extent. N-ethylmaleimide, an inhibitor of erythrocyte Ca(2+)-ATPase, prevents such restoration. Electron micrographs reveal that numerous larger intramembranous particle can be observed on the P-faces of freeze-fractured resealed ghosts in the absence of a transmembrane Ca2+ gradient.

Effect of ganglioside GM3 on the activity and conformation of reconstituted Ca2+-ATPase

Trace amounts of gangliosides were found in rabbit skeletal muscle sarcoplasmic reticulum and their main part was shown, by high performance thin layer chromatography. to be GM3. Addition of GM3 to the soybean phospholipids used for reconstitution of proteoliposomes markedly increased ATP hydrolysis as well as Ca2+ uptake activity of sarcoplasmic reticulum Ca2+-ATPase incorporated into the proteoliposomes. Conformation changes of Ca2+-ATPase induced by GM3 were also observed by intrinsic fluorescence and circular dichroism measurements.

Fluorescence study on ligand induced conformational changes of human erythrocyte glucose transporter

The nanosecond time-resolved fluorescence and fluorescence lifetime quenching have been used to detect the conformational changes of human erythrocyte glucose transporter induced by its ligands. Results show that D-glucose can decrease the fluorescence lifetimes, while L-glucose exhibits no effect. The fluorescence lifetime quenching results also show that in the presence of D-glucose, the quenching efficiency of hypocrellin B (a hydrophobic quencher obtained from a parasitic fungus, growing in Yunnan, China) is lower than in the presence of L-glucose. It can be deduced that the conformational changes of human erythrocyte glucose transporter induced by D-glucose are different from those induced by L-glucose.

Transmembrane Ca2+ gradient and function of membrane proteins

This review will focus on the recent advance in the study of effect of transmembrane Ca2+ gradient on the function of membrane proteins. It consits of two parts: 1. Transmembrane Ca2+ gradient and sarcoplasmic reticulum Ca(2+)-ATPase; 2. Effect of transmembrane Ca2+ gradient on the components and coupling of cAMP signal transduction pathway. The results obtained indicate that a proper transmembrane Ca2+ gradient may play an important role in modulating the conformation and activity of SR Ca(2+)-ATPase and the function of membrane proteins involved in the cAMP signal transduction by mediating the physical state change of the membrane phospholipids.

Zn(2+)-mediated domain-domain communication in human erythrocyte band 3

Zn2+ could inhibit the anion transport activity of spectrin-stripped inside-out human erythrocyte membrane vesicles (IOVs). Removal of the cytoplasmic domain from Band 3 by trypsin could eliminate Zn2+ inhibition. The location of a Zn(2+)-binding site was confirmed by atomic absorbance spectrometry. The results of time-resolved fluorescence and intrinsic fluorescence quenching by KI and hypocrellin B (a photosensitive pigment obtained from a parasitic fungus growing in Yunnan, China) showed that the cytoplasmic domain is necessary for the Zn(2+)-induced conformational changes of the whole molecule as well as the membrane domain of Band 3. It is suggested that Zn2+ induced a conformational change in the cytoplasmic domain of Band 3, which in turn was transmitted to the membrane domain, resulting in an inhibition of activity of Band 3. Such long-range conformational changes may imply that the cytoplasmic domain is poised to function as a cytosolic arm in order to modulate the structure of the membrane domain of Band 3.

Cytoplasmic Ca2+ inhibits the glucose transporter of human erythrocytes

The effect of Ca2+ on the glucose transporter of human erythrocytes was investigated. The results showed that extracellular Ca2+ had no effect. But, the glucose transport of erythrocytes was markedly inhibited due to the increase in cytoplasmic Ca2+ concentration by addition of ionophore A23187. The Ca2+ inhibition exhibited a dose-dependent manner with an apparent half maximal concentration of 250 microM and could not be recovered by 10 mM EGTA. Unlike Ca2+, Mg2+ did not affect the glucose transporter.

Fluorescence study on transmembrane Ca2+ gradient-mediated conformation changes of sarcoplasmic reticulum Ca(2+)-ATPase

The conformational states of Ca(2+)-ATPase in sarcoplasmic reticulum (SR) vesicles with or without a thousand-fold transmembrane Ca2+ gradient have been studied by fluorescence spectroscopy and fluorescence quenching. In consequence of the establishment of the transmembrane Ca2+ gradient, the steady-state fluorescence results revealed a reproducible 8% decrease in the intrinsic fluorescence while time-resolved fluorescence measurements showed that 13 tryptophan residues in SR.Ca(2+)-ATPase could be divided into three groups. The fluorescence lifetime of one of these groups increased from 5.5 ns to 5.95 ns in the presence of a Ca2+ gradient. Using KI and hypocrellin B (a photosensitive pigment obtained from a parasitic fungus, growing in Yunnan, China), the fluorescence quenching further indicated that the dynamic change of this tryptophan group, located at the protein-lipid interface, is a characteristic of transmembrane Ca2+ gradient-mediated conformational changes in SR.Ca(2+)-ATPase.

Zn2+ inhibits the anion transport activity of band 3 by binding to its cytoplasmic tail

Zn2+ can induce a conformational change of Band 3 with concomitant inhibition of its anion transport activity of human erythrocyte membrane vesicles only from the cytoplasmic side. The Zn2+ inhibition exhibits a dose-dependent manner with an apparent half maximal concentration of 50 microM ZnCl2 and can be reversed by 0.5 mM EDTA, but not by 1 mM dithiothreitol. The Zn2+ effect is specific and no similar inhibitory action could be observed by other divalent cations (Cu2+, Mn2+, Mg2+ or Sr2+).

Transmembrane Ca2+ gradient-mediated change of fluidity in the inner layer of phospholipids modulates Ca(2+)-ATPase of sarcoplasmic reticulum

Sarcoplasmic reticulum (SR) vesicles with (1000 folds) or without transmembrane Ca2+ gradient have been prepared. Different fluorescence probes (DPH, TMA-DPH and n-AS), were used to determine the effect of transmembrane Ca2+ gradient on the lipid fluidity both in outer and inner layer of Ca(2+)-ATPase-containing SR vesicles. The results showed that transmembrane Ca2+ gradient could significantly decrease the fluidity of the inner layer of SR membrane, while no obvious change was monitored in the outer layer. This may be deduced that Ca(2+)-ATPase might be modulated mainly by the transmembrane Ca2+ gradient-mediated alteration of physical state of phospholipid in the inner layer of SR membrane.

[The specificity of modulation of sarcoplasmic reticulum Ca(2+)-ATPase by transmembrane Ca2+ gradient]

We have previously reported that transmembrane Ca2+ gradient-mediated changes in lipid fluidity could modulate the conformation and enzyme activity of sarcoplasmic reticulum (SR) Ca(2+)-ATPase. The aim of this paper is to explore the specificity of transmembrane Ca2+ gradient-mediated modulation of SR Ca(2+)-ATPase. The results showed that such specificity exhibited in two aspects: 1. The modulation could not be ascribed to transmembrane potential resulted from the transmembrane Ca2+ gradient, Dissipation of transmembrane potential by FCCP (carbonylcyanide-p-trifluoromethoxyphenylhydrazone) could not affect the activity of SR Ca(2+)-ATPase. 2. Transmembrane Sr2+ gradient had little effect on the enzyme activity of SR Ca(2+)-ATPase. A significant difference between the effect of transmembrane Ca2+ and Sr2+ gradient on the lipid fluidity was detected in the middle region of bilayer of Ca(2+)-ATPase incorporated proteoliposomes using a set of n-AS [n-(9-anthroyloxy) fatty acids] fluorescence polarization probes. It is known that Ca2+ binding domain of SR Ca(2+)-ATPase is just located in the middle region of bilayer, hence it may be deduced that possibly, membrane lipids are involved in transmembrane Ca2+ gradient-mediated modulation of Ca(2+)-ATPase.

Transmembrane Ca2+ gradient-mediated modulation of sarcoplasmic reticulum Ca(2+)-ATPase

Ca(2+)-ATPase from skeletal muscle sarcoplasmic reticulum was reconstituted into liposomes with (100-1000 fold) or without transmembrane Ca2+ gradient. The highest enzyme activity and Ca2+ uptake were observed in the vesicles without transmembrane Ca2+ gradient. If there existed transmembrane Ca2+ gradient, no matter what the direction was, a lower activity would appear. Dissipation of transmembrane Ca2+ gradient by A23187 could lead to a change in enzyme activity of incorporated Ca(2+)-ATPase. A concomitant change of lipid fluidity of proteoliposomes with that of enzyme activity and Ca2+ uptake was observed. The inhibition of Ca(2+)-ATPase by the transmembrane Ca2+ gradient could be observed in the PC-PE vesicles, but not in the PS-PE or PG-PE proteoliposomes.

Divalent cation and lipid-protein interactions of biomembranes

Divalent cations play an important role in the functions of biomembranes. This review deals with three topics: (1) Mg(2+)-mediated change in physical state of phospholipid induces conformation and activity change of reconstituted mitochondrial H(+)-ATPase, (2) a proper transmembrane Ca2+ gradient is essential for the higher enzymatic activity of adenylate cyclase, and (3) role of transmembrane Ca2+ gradient in the modulation of reconstituted sarcoplasmic reticulum Ca(2+)-ATPase activity.

Effect of transmembrane Ca2+ gradient on conformation and enzyme activity of reconstituted adenylate cyclase

Adenylate cyclase from bovine brain cortex was reconstituted into asolectin liposomes with (500-fold) or without transmembrane Ca2+ gradient. The enzyme activity of four types of proteoliposomes (the active center of enzyme exposing outside) was compared. The highest adenylate cyclase activity was observed in the vesicles with outside lower Ca2+ concentration (approximately 10(-6) mol/L, similar to the physiological condition). If the transmembrane Ca2+ gradient was in the inverse direction (i.e. outside higher Ca2+ concentration, 0.5 mmol/L), a lowest enzymatic activity would appear. The difference in enzymatic activity between the two types of proteoliposomes could be diminished following the addition of Ca2+ ionophore A23187. Proteoliposomes without transmembrane Ca2+ gradient exhibited intermediate activities. The conformation difference of adenylate cyclases in the above-mentioned proteoliposomes was also detected by measuring intrinsic fluorescence and fluorescence quenching with KI.

A proper transmembrane Ca2+ gradient is essential for the higher enzymatic activity of adenylate cyclase

Adenylate cyclase from bovine brain cortex was reconstituted into liposomes with (1000 fold) or without transmembrane Ca2+ gradient. The highest enzyme activity (the active center of enzyme exposing outside) was observed in the vesicles with lower Ca2+ concentration outside (approximately 10(-6) M, similar to physiological condition). If the transmembrane Ca2+ gradient was in the inverse direction (i.e. higher Ca2+ concentration outside, 1 mM), a lowest enzyme activity would appear. Such a difference could be diminished following addition of A23187. Obtained results showed that a proper transmembrane Ca2+ gradient is essential for the optimal fluidity of phospholipid bilayer, favouring the formation of suitable conformation of adenylate cyclase with higher enzyme activity.