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Biomedical subjects

M R Carlson

Publications and source records attributed to M R Carlson.

At least 19 recordsLinked to original sources
PubMed2005

Novel bismuth-metronidazole-tetracycline triple-layer tablet for treatment of Helicobacter pylori.

BACKGROUND: Current anti-Helicobacter pylori treatment regimens are costly and because of the increasing antibiotic resistance, are becoming ineffective. AIM: To evaluate a triple-layer tablet containing 100 mg bismuth subcitrate, 250 mg metronidazole, and 250 mg tetracycline in a single triple-layer tablet. METHODS: H. pylori-infected adult patients received bismuth-metronidazole-tetracycline (two tablets, t.d.s.) and ranitidine (300 mg) once daily for 14 days. Efficacy was determined using 13C-urea breath testing. RESULTS: Thirty-three of 35 enrolled patients were available for evaluation; using the protocol-specified modified intention-to-treat analysis, five failed treatment, two were lost to follow-up (cure rate per-protocol = 85.7%, intention-to-treat = 78.7%). The cure rate among metronidazole-susceptible strains was 100% (22 of 22) (95% confidence interval 84-100%) compared with 55% (five of nine intention-to-treat) (95% confidence interval 21-86%) among metronidazole-resistant strains. In four cases, therapy was truncated at 4-7 days because of side-effects; yet the treatment was effective in three. The three metronidazole-susceptible but clarithromycin-resistant infections were cured. CONCLUSION: This novel triple-layer tablet combination therapy was effective in all patients with metronidazole-susceptible H. pylori and many of those with resistant organisms. A greater degree of acid suppression may further improve effectiveness.

Adolescent↗
PubMed2001

Expression of Hoxb13 and Hoxc10 in developing and regenerating Axolotl limbs and tails.

The expression of Hox complex genes in correct spatial and temporal order is critical to patterning of the body axis and limbs during embryonic development. In order to understand the role such genes play in appendage regeneration, we have compared the expression of two 5' Hox complex genes: Hoxb13 and Hoxc10 during development and regeneration of the body axis and the limbs of axolotls. In contrast to higher vertebrates, Hoxb13 is expressed not only in the tip of the developing tail, but also in the distal mesenchyme of developing hind limbs, and at low levels in developing forelimbs. Hoxc10 is expressed as two transcripts during both development and regeneration. The short transcript (Hoxc10S) is expressed in the tip of the developing tail, in developing hind limbs, and at low levels in developing forelimbs. The long transcript (Hoxc10L) is expressed in a similar pattern, with the exception that no expression in developing forelimbs could be detected. Hoxb13 and both transcripts of Hoxc10 are expressed at high levels in the regenerating spinal cord during tail regeneration, and in both regenerating hind limbs and forelimbs. The up-regulation of expression of these genes during forelimb regeneration, relative to the very low levels of expression during forelimb development, suggests that they play a critical and perhaps unique role in regeneration. This is particularly true for Hoxc10L, which is not expressed during forelimb development, but is expressed during forelimb regeneration; thus making it the first truly "regeneration-specific" gene transcript identified to date.

Ambystoma↗
PubMed1999

Expression of Mmp-9 and related matrix metalloproteinase genes during axolotl limb regeneration.

One of the earliest events in limb regeneration is the extensive remodeling of the extracellular matrix (ECM). Matrix metalloproteinases (MMPs) are a family of matrix degrading enzymes that have been identified in both normal and disease states. Using RT-PCR and cDNA library screening, we have isolated sequences homologous to four different Mmp genes. The spatial and temporal expression of one of these, Mmp-9, has been analyzed during axolotl limb regeneration. Northern blot analysis identifies a 3.8 kb transcript that is abundantly expressed during regeneration, and whole-mount in situ hybridization has uncovered an unusual bi-phasic expression pattern. The first phase begins at 2 hours after amputation, and expression is confined to the healed wound epithelium. This phase continues for 2 days, showing peak expression at 14 hours after amputation. This early phase may be needed to retard reformation of the basal lamina of the epidermis, and thereby facilitate the epidermal-mesenchymal interactions required for successful regeneration. The second phase begins a few days later when a small blastema has formed. During this phase, expression is in the mesenchyme, localized to cells around the tips of the cut skeletal elements. This expression is maintained through several stages until redifferentiation begins. The timing and position of the second phase of expression is consistent with a role for Mmp-9 in the removal of damaged cartilage matrix. We have also discovered that the time of onset of Mmp-9 expression is sensitive to denervation, which causes a delay of several hours. Finally, retinoids, known for their dramatic effects on the pattern of regenerating limbs, can cause a down regulation of Mmp-9 expression. Dev Dyn 1999;216:2-9.

Ambystoma↗
PubMed1998

Expression of Msx-2 during development, regeneration, and wound healing in axolotl limbs.

Msx genes are transcription factors that are expressed during embryogenesis of developing appendages in regions of epithelial-mesenchymal interactions. Various lines of evidence indicate that these genes function to maintain embryonic tissues in an undifferentiated, proliferative state. We have identified the axolotl homolog of Msx-2, and investigated its expression during limb development, limb regeneration, and wound healing. As in limb buds of higher vertebrates, axolotl Msx-2 is expressed in the apical epidermis and mesenchyme; however, its expression domain is more extensive, reflecting the broader region of the apical epidermal cap in amphibians. Msx-2 expression is downregulated at late stages of limb development, but is reexpressed within one hour after limb amputation. Msx-2 is also reexpressed during wound healing, and may be essential in the early stages of initiation of the limb regeneration cascade.

Ambystoma↗
PubMed1981

Extraocular muscle forces in normal human subjects.

Actively developed horizontal muscle forces and tissue stiffnesses were measured in 29 normal orthophoric volunteer subjects (18 to 33 years old) by means of noninvasive length-tension forceps. Mean active fixation force developed at 50 deg extreme gaze was 26% greater for the medial rectus (74.8 gm) than for the lateral rectus (59.1 gm). The variation of maximum active force among individuals was 2:1 (48 to 103 gm). These muscles developed up to 25% of their maximum active force out of their field of action. Active (counter) hysteresis force differences of over 10 gm were measured between nasal and temporal gaze directions. This study suggests that a muscle which develops a maximum active force of less than 45 gm would be suspect as paretic. Variations from the normal pattern of reciprocal innervation, reflected in the graded active force of individual muscle contraction, may help in understanding some types of oculomotor pathology. The mean tissue stiffness-restraining movement of the globe in the nasal direction (1.05 gm/deg) is 11% greater than in the temporal direction (0.94 gm/deg). This is consistent with a stronger medial rectus balanced by a greater load. Variation of stiffness of 2:1 was observed among individuals; 0.8 to 1.7 gm/deg pulling nasally and 0.77 to 1.2 gm/deg temporally. Passive hysteresis and viscous force differences of over 10 gm were observed between the passive forced pull and normal spring-return of the eye. Large stiffnesses may be normal if balanced by large active forces. Abrupt changes of the length-tension curve indicate the magnitude and location of restrictions.

Adolescent↗
PubMed1979

Lateral incomitancy in intermittent exotropia: cause and surgical therapy.

A hypothesis, previously proposed, of tight medial rectus muscles in conjunction with tight lateral rectus muscles associated with exodeviations as a cause of lateral incomitancy in intermittent exotropia is supported by clinical management. Three patients with these findings underwent bilateral medial rectus and lateral rectus recessions by means of the adjustable rectus recession technique. Primary position alignment was achieved, and rotations were balanced with the alleviation of the lateral incomitancy. The lateral rectus muscles were recessed an amount more than usual in order to compensate for the recession of the medial rectus muscles.

Adolescent↗
PubMed1979

An adjustable transposition procedure for abduction deficiences.

We used an adjustable transposition procedure in two cases of horizontal abduction deficiency (one of lateral rectus palsy and one of Duane syndrome with marked co-contraction). Primary position balanced alignment and maximum balanced rotations were obtained without inducing vertical deviation as the result of the transposition. The vertical force vectors were neutralized by the self-adjusting nature of the vertical rectus union. The procedure allowed for both intraoperative and postoperative adjustment of the result.

Child↗
PubMed1977

Vertical saccadic velocity determination in superior oblique palsy.

Vertical saccadic velocities were measured in various horizontal gaze positions in patients with known superior oblique weakness and compared to similar measurements in a normal control group. Marked slowing of the down saccade in the adducted position occurred in the patients with superior oblique weakness and not in the controls. This suggests that it is possible to differentiate oblique and rectus function by saccadic velocity analysis.

Electrooculography↗
PubMed1976

Central retinal artery occlusion after carotoid angiography.

A 4-year-old boy had a case of ischemic infarction of the retina that occurred immediately after percutaneous carotoid angiography via a femoral percutaneous approach. This appears to be the youngest reported patient with this complication.

Angiography↗
PubMedDate not supplied

Combination of platelet-derived growth factor-BB and insulin-like growth factor-I is more effective than platelet-derived growth factor-BB alone in stimulating complete healing of full-thickness wounds in "older" diabetic mice.

Platelet-derived growth factor and insulin-like growth factor-I have been shown to interact synergistically to enhance repair of skin wounds in normal healing swine. Platelet-derived growth factor alone has shown promise in treating human chronic ulcers. The objective of this study was to compare the wound healing effects of platelet-derived growth factor-BB alone with those of a combination of platelet-derived growth factor-BB and insulin-like growth factor-I in an improved model with the use of "older" animals with diabetes. Older diabetic (db/db) mice (>15 weeks of age) have less elevated insulin levels compared with young db/db mice. The serum insulin levels in the older animals is 1.0 to 2.5 times that of the nondiabetic animals, a similar increase to that which occurs in human patients with type II diabetes. Healing was evaluated in two studies involving a total of 104 animals. Treatment groups included the following: 4.0 microg/cm(2) of platelet-derived growth factor-BB, 40.0 microg/cm(2) of platelet-derived growth factor-BB, 4.0 microg/cm(2) of both platelet-derived growth factor-BB and insulin-like growth factor-I or vehicle. All growth factors were applied topically in a methylcellulose vehicle to full-thickness wounds every other day for 24 days. Efficacy end points were median and mean time to complete healing and rate of wound closure. The median time to complete healing for animals receiving the platelet-derived growth factor-BB/insulin-like growth factor-I combination was 38% and 33% faster (p < 0.001) than animals receiving 4.0 microg/cm(2) and 40.0 microg/cm(2) of platelet-derived growth factor-BB, respectively. The mean time to complete healing for platelet-derived growth factor/insulin-like growth factor-I treated animals was 31% and 29% faster (p < 0.001) than 4.0 microg/cm(2) and 40.0 microg/cm(2) platelet-derived growth factor-BB treated animals, respectively. Wounds treated with 4.0 microg/cm(2) platelet-derived growth factor-BB/insulin-like growth factor-I healed, on average, in 22 days compared with 31 days for 40.0 microg/cm(2) platelet-derived growth factor-BB alone and 38 days for vehicle. Also, platelet-derived growth factor-BB/insulin-like growth factor-I significantly improved the rate of wound closure throughout the duration of the studies compared with either dose of platelet-derived growth factor-BB alone (p < 0.005) or vehicle (p < 0.001). In conclusion, the data show that the combination of platelet-derived growth factor-BB and insulin-like growth factor-I is more effective than platelet-derived growth factor-BB alone at the doses tested or vehicle treatment in stimulating cutaneous wound healing in older, diabetic mice.

Journal Article↗