Biomedical subjects

Masahiro Koizumi

Publications and source records attributed to Masahiro Koizumi.

15 recordsLinked to original sources

PubMed2006

A case of nonrotation of the midgut with a middle mesenteric artery.

In 2002, we came across a very rare case of nonrotation of the midgut with a middle mesenteric artery (MM) (tentative name). It was found in a 73-year-old Japanese female cadaver donated for student dissection at Kumamoto University. In this case, the small intestine occupied the right half of the abdominal cavity and the large intestine occupied the left half. The caecum was situated on the anterior inferior part of the abdominal cavity near the midline. The duodenum (Du) was fused to the posterior abdominal wall. The small intestine except the Du and the ascending colon were suspended from the posterior abdominal wall by the mesentery, but the remainder of the colon was fused to the left posterior abdominal wall. In addition, an anomalous branch arose from the abdominal aorta between the superior and inferior mesenteric arteries (SM and IM) in this case. It chiefly supplied the ascending and the transverse colons and anastomosed with the SM and IM, respectively, through the marginal arteries. It is very rare that these anomalies appear simultaneously in one body. In this case, it is difficult to declare that the existence of the MM directly caused the nonrotation of the midgut, but it is reasonable to suppose some kind of relation between them.

Aged↗

PubMed2006

A middle meningeal artery which arises from the internal carotid artery in which the first branchial artery participates.

A middle meningeal artery arising from the internal carotid artery was found in the right half of the head of an 85-year-old male cadaver during student dissection practice. It arose from the lateral aspect of the internal carotid artery in the carotid canal, arrived at the foramen lacerum after running forward. It then ran backward under the trigeminal ganglion and took the usual course after passing its posterior margin. On one hand, the maxillary artery did not issue the middle meningeal artery, gave off only a small twig supplying the lateral pterygoid muscle at the corresponding position. It was corroborated by the fact that the foramen spinosum was absent in this example. During usual development, the middle meningeal artery primarily springs from the supraorbital branch of the stapedial artery that arises from the dorsal part of the second branchial artery. Later, by the formation of the external carotid artery connecting with the common trunk of the infraorbital and mandibular branches (maxillomandibular division) of the stapedial artery and by the atrophy of the proximal part of it, the middle meningeal artery is finally supplied by the external carotid artery. But in this example, it is supposed that the middle meningeal artery arose from a more distal position of the internal carotid artery owing to the persistence of the anastomosis between the dorsal part of the first branchial artery and the supraorbital branch and the interruption of the connection between the supraorbital branch and maxillomandibular division of the stapedial artery.

Aged, 80 and over↗

PubMed2006

The deep axillary artery.

An aberrant axillary artery running deep to the brachial plexus during its course was observed. The brachial plexus in this case was formed by the fourth cervical nerve to the first thoracic nerve and the radial nerve received a small nerve bundle (accessory radial nerve root) from the posterior aspect of the lower trunk. The axillary artery passed between the lateral and the medial cords of the brachial plexus, the same as for an ordinary axillary artery. In addition, it passed between their posterior divisions, forming the posterior cord, and further ran between the radial nerve root and the accessory radial nerve root from deep to superficial. This axillary artery was recognized as the deep axillary artery, the same as the axillary artery we have reported previously. It was thought that the branches to the subscapularis and serratus anterior muscles, nutrient branch to the radial nerve root and the subscapular artery played important roles in its formation.

Aged, 80 and over↗

PubMed2006

Double innervation of the anterior belly of the digastric muscle.

We came across a very rare case in which the anterior belly of the digastric muscle was innervated by the twigs of the facial nerve in addition to those of the mylohyoid nerve. The anomaly was discovered in the cadaver of an 84-year-old Japanese male bequeathed for a training seminar in gross anatomy at Kumamoto University in 2003. One twig issued from the marginal mandibular branch of the facial nerve and entered the central region of the anterior belly of the digastric muscle on the lower surface. The other twig issued from the stylohyoid branch of the facial nerve, descended along the lateral margin of the stylohyoid muscle and entered the anterior belly of the digastric muscle on the lower surface near the intermediate tendon. The twig from the marginal mandibular branch was distributed to the shallow (lower) and central region near the medial margin of the anterior belly. The twig from the stylohyoid branch was distributed to the shallow and lateral region of the anterior belly. These two twigs communicated with the mylohyoid nerve at several peripheral parts. Textbooks on general anatomy make mention of only one nerve, the mylohyoid, supplying the anterior belly of the digastric muscle. However, the present case manifests that the anterior belly receiving twigs from the mylohyoid and facial nerves is formed with the second brachial component as well as the first.

Aged, 80 and over↗

PubMed2005

Attritional rupture of the flexor digitorum profundus tendon to the index finger caused by accessory carpal bone in the carpal tunnel: a case report.

We describe a case of attritional rupture of a flexor digitorum profundus tendon to the right index finger in a 73-year-old man by an accessory carpal bone located on the palmar side of the capitate and triquetrum. The radial edge of the accessory carpal bone appeared to be the cause of the rupture. Excision of the accessory carpal bone, bridge tendon graft using the palmaris longus tendon, and early controlled mobilization after surgery led to a successful outcome.

Aged↗

PubMed2004

An aberrant axillary artery penetrating the origin of the radial nerve from deep to superficial.

An aberrant axillary artery that penetrated the radial nerve from deep to superficial during its course, was observed. The brachial plexus in the present case was classified as the Adachi's C-type brachial plexus. Further, an accessory radial root existed, which was a nerve bundle branching from the deep aspect of the inferior trunk and communicating with the radial root from the posterior cord to form the radial nerve. The axillary artery went on along the lower border of the brachial plexus and passed between the radial root and the accessory radial root from deep to superficial at its third section. As the axillary artery penetrated the origin of the radial nerve from deep to superficial, it was judged to reach deep under the posterior cord, hence deeper than the brachial plexus.

Aged↗

PubMed2004

Scalenus muscles in macaque monkeys.

The attachment and innervation of the scalenus muscles in both sides of two Japanese monkeys and a rhesus monkey were observed to discuss their morphological significance while comparing their findings in humans. The scalenus ventralis muscle in macaques had almost the same attachments as the scalenus anterior muscle in humans and was innervated by the cervical nerve branches, which were lower in spinal segment than in humans and had a close relationship with the branches to the intertransversus ventralis muscles. Furthermore, the scalenus ventralis muscle was penetrated by the phrenic nerve in all cases observed. The posterior part of the scalenus muscle in macaques (the scalenus dorsalis muscle) was divided into short (the scalenus dorsalis brevis) and long (the scalenus dorsalis longus) parts according to their attachments. The former was attached to the transverse processes of the lowest two cervical vertebrae and the first rib, whereas the latter was attached to the 3rd-5th ribs. It is notable that the scalenus dorsalis muscles in macaques were innervated by branches from the long thoracic nerve in addition to direct branches from the cervical nerve roots. In addition, the scalenus dorsalis longus was supplied by twigs from the lateral cutaneous branches of the 2nd and 3rd intercostal nerves. This indicates that the scalenus dorsalis muscles contain a muscular component derived from the upper limb girdle musculature, unlike the human scalenus muscles, which have been considered to belong to the cervical trunk muscles.

Animals↗

PubMed2004

The influence of motor axon misdirection on muscle contraction force in early nerve repair in a rat sciatic nerve model.

We examined the influence of misdirection of regenerating motor axons toward the distal sensory Schwann tubes on the muscle contraction force in early nerve repair using a rat sciatic nerve model. At 0, 1, 2, 4 and 8 weeks after severing the tibial, peroneal and sural nerves, the proximal stump of the tibial nerve was anastomosed with the distal stumps of both the peroneal and sural nerves using tubulisation (n=10 in each of five groups). We intentionally used the distal stump of the sural nerve (a sensory nerve) to induce regeneration in motor axons from the proximal tibial nerve stump toward the distal sensory nerve stump. Twenty-four weeks after nerve repair, isometric contraction force and wet weight of the anterior tibial muscle were measured, and the numbers of regenerated myelinated axons (motor and sensory) in the distal sural and peroneal nerves were counted. The rates of sural nerve regeneration were significantly higher at weeks 0 and 1 than at the later repair times. However, muscle contraction force and muscle wet weight did not differ significantly between groups in which nerves were repaired within four weeks of severance. These results indicate that peripheral nerve repair within four weeks of severance does not influence the muscle contraction force of single muscle despite the misdirection of motor axons toward the distal sensory Schwann tubes.

Anastomosis, Surgical↗

PubMed2003

Crystal structure of the complex of porcine pancreatic elastase with TEI-8362.

The crystal structure of porcine pancreatic elastase (PPE) complexed with a new benzoxazinone inhibitor, TEI-8362, of human neutrophil elastase (HNE) was determined at 1.8 A resolution. The hydroxyl oxygen of Ser195 opened the benzoxazinone by nucleophilic attack and formed a covalent bond with the carbonyl carbon. Hydrophobic interaction between the terminal benzene of TEI-8362 and the S4 pocket is reinforced by the side chain of Arg217 and has an impact on the ligand binding conformation. Two additional interactions with the oxyanion hole and His57 are introduced to the benzoxazinone structure of TEI-8362. These combinatorial interactions will also exist in HNE and cause high preference of TEI-8362 for HNE.

Animals↗

PubMed2003

Derivation of the anterior belly of the digastric muscle receiving twigs from the mylohyoid and facial nerves.

The anterior belly of the digastric muscle is usually supplied by the mylohyoid nerve, and in general anatomy textbooks, the anterior belly is invariably described as receiving no other nerve except the mylohyoid nerve. In fact, however, it is sometimes supplied by a branch of the facial nerve in addition to the mylohyoid nerve. Such cases were found in 8 bodies or 9 head sides among 539 bodies or 1078 head sides of Japanese subjects. Those nine cases were investigated in detail and it was clarified that they had the following three characteristics in common: (1) the twig originating from the facial nerve appears as the twig of the stylohyoid branch in most cases, (2) the twig from the facial nerve enters the anterior belly on its lower (shallow) surface and the twig of the mylohyoid nerve on its upper (deep) surface, (3) the twig of the mylohyoid nerve is distributed to the deep region and the twig of the stylohyoid branch is distributed to the shallow region of the anterior belly. From these results, it was concluded that the anterior belly, receiving the twigs of the mylohyoid and facial nerves, had been formed by secondarily combining the most ventral and rostral part of the primordium of the stylohyoid muscle in the second branchial arch with the caudal part of the primordium of the anterior belly in the first branchial arch.

Autopsy↗

PubMed2003

Computer-aided design of a factor Xa inhibitor by using MCSS functionality maps and a CAVEAT linker search.

We have investigated a new approach to efficiently find a novel inhibitor against a serine protease (i.e. an activated coagulation factor X, FXa) by using de novo design programs and the X-ray crystal structure of the target enzyme. FXa is a coagulant enzyme that generates thrombin (a serine protease) and participates in both intrinsic and extrinsic coagulation pathways. We adopted multiple copy simultaneous search (MCSS) and CAVEAT linker search techniques, which disclosed a novel FXa inhibitor (T01312) consisting of two binding moieties (the benzamidinyl and adamantyl groups) and a linker unit (the carboxybenzylamine group). The inhibitory activity of T01312 against FXa was determined to be a small K(i)-value of 48nM, which is two orders of magnitude smaller than that against thrombin. An X-ray crystal analysis of T01312 complexed with trypsin (an analogue of FXa) and docking studies of T01312 with trypsin and FXa showed that: (i) the benzamidinyl group is a predominant binding moiety in the anionic pocket (S1 site) with an asparatic acid residue; (ii) a hydrophobic pocket (S4 site) is the binding site of the adamantyl group; (iii) the carboxylate group of the linker contributes to the selectivity for FXa against thrombin. Thus, the combination of the knowledge of the X-ray crystal structure of the target molecule with MCSS and CAVEAT linker search techniques proved to be an effective hit-finding method that does not require the screening of huge compound libraries.

Antithrombin III↗

PubMed2003

Aberrant axillary artery descending deep beneath the brachial plexus.

An aberrant axillary artery that descended deep beneath the brachial plexus during its course was observed. The artery passed between the lateral and medial cords, as would an ordinary axillary artery, but further passed between the posterior divisions forming the posterior cord. The axillary artery turned medially to emerge from the lower border of the medial cord and finally ran as an ordinary artery. The aberrant axillary artery is judged to reach deeper to the brachial plexus, because it penetrated the posterior division of the brachial plexus from superficial to deep. It is possible to account for the formation of this artery as one of the combinations of the ordinary axillary artery and its branches, with the positional relationships between the brachial plexus.

Aged↗

PubMed2002

Anomalous lumbrical muscles arising from the deep surface of flexor digitorum superficialis muscles in man.

During anatomy practice in 1999 at Kumamoto University School of Medicine, the anomalous lumbrical muscles originating in the forearm were observed in both arms of a cadaver. These muscles, originating from the intermediate tendon of the deep layer of the flexor digitorum superficialis for the index finger (FDS-II), passed through the carpal tunnel to join the insertion of the first lumbrical muscle, and formed a muscle belly near the origin in the left and at the insertion in the right. The left anomalous muscle was innervated by a branch of the median nerve just proximal to the carpal tunnel. The right one received a twig from the nerve to the first lumbrical muscle. Tracing the nerve fibers by peeling off the epi- and perineurium clarified that the nerve fibers supplying the left anomalous muscle formed a common bundle with the fibers to the first lumbrical muscle. Therefore, these anomalous muscles are considered to be the accessory lumbrical muscles arising from the forearm. The three accessory lumbricalis, including one case reported by Yamada (1986), received branches which had slightly different origins from proximally (nerve to the distal belly of FDS-II) to distally (nerve to the first lumbricalis). Accordingly the position of the muscle belly shifted distally. The occurrence of these unusual accessory lumbrical muscles indicates that the distal belly of FDS-III and the first lumbricalis are derived from a common muscle origin and presents an important clue to the phylogenetic origin of the flexor digitorum superficialis.

Aged↗

PubMed2002

A histologic study of extralobar pulmonary sequestration and its anomalous artery as a clue to its development.

In 1997, an anomalous small mass of soft tissue was found in the left thoracic cavity of a Japanese male cadaver during student dissection practice. It was linked only by branches from the thoracic aorta, hemiazygos vein and greater splanchnic nerve, with no connection to the normal lung by vessels or airway. Examination of cut sections clarified that this anomalous small tissue mass was an extralobar pulmonary sequestration (EPS). Many cases of pulmonary sequestration have been reported from the clinical aspect, but there are few from a purely anatomical viewpoint. In the present case, detailed gross anatomical and histologic observations clarified that the anomalous artery supplying the sequestration resembled an elastic artery. In view of the findings of other reports, the anomalous arteries are divided into two types, the elastic type such as the pulmonary artery and the muscular type such as the bronchial artery. So it is thought that the histologic observation of an anomalous artery in comparison with normal pulmonary and bronchial arteries may offer an important clue to consider in elucidating the origin and development of pulmonary sequestration.

Aged↗

PubMed2002

Rodent alpha-chymases are elastase-like proteases.

Although the alpha-chymases of primates and dogs are known as chymotrypsin-like proteases, the enzymatic properties of rodent alpha-chymases (rat mast cell protease 5/rMCP-5 and mouse mast cell protease 5/mMCP-5) have not been fully understood. We report that recombinant rMCP-5 and mMCP-5 are elastase-like proteases, not chymotrypsin-like proteases. An enzyme assay using chromogenic peptidyl substrates showed that mast cell protease-5s (MCP-5s) have a clear preference for small aliphatic amino acids (e.g. alanine, isoleucine, valine) in the P1 site of substrates. We used site-directed mutagenesis and computer modeling approaches to define the determinant residue for the substrate specificity of mMCP-5, and found that the mutant possessing a Gly substitution of the Val at position 216 (V216G) lost elastase-like activity but acquired chymase activity, suggesting that the Val216 dominantly restricts the substrate specificity of mMCP-5. Structural models of mMCP-5 and the V216G mutant based on the crystal structures of serine proteases (rMCP-2, human cathepsin G, and human chymase) revealed the active site differences that can account for the marked differences in substrate specificity of the two enzymes between elastase and chymase. These findings suggest that rodent alpha-chymases have unique biological activity different from the chymases of other species.

Amino Acid Sequence↗